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5 <title>LLVM Assembly Language Reference Manual</title>
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7 <meta name="author" content="Chris Lattner">
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9 content="LLVM Assembly Language Reference Manual.">
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15 <div class="doc_title"> LLVM Language Reference Manual </div>
17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#introduction">Introduction</a></li>
19 <li><a href="#identifiers">Identifiers</a></li>
20 <li><a href="#highlevel">High Level Structure</a>
22 <li><a href="#modulestructure">Module Structure</a></li>
23 <li><a href="#linkage">Linkage Types</a></li>
24 <li><a href="#callingconv">Calling Conventions</a></li>
25 <li><a href="#namedtypes">Named Types</a></li>
26 <li><a href="#globalvars">Global Variables</a></li>
27 <li><a href="#functionstructure">Functions</a></li>
28 <li><a href="#aliasstructure">Aliases</a></li>
29 <li><a href="#paramattrs">Parameter Attributes</a></li>
30 <li><a href="#fnattrs">Function Attributes</a></li>
31 <li><a href="#gc">Garbage Collector Names</a></li>
32 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
33 <li><a href="#datalayout">Data Layout</a></li>
36 <li><a href="#typesystem">Type System</a>
38 <li><a href="#t_classifications">Type Classifications</a></li>
39 <li><a href="#t_primitive">Primitive Types</a>
41 <li><a href="#t_floating">Floating Point Types</a></li>
42 <li><a href="#t_void">Void Type</a></li>
43 <li><a href="#t_label">Label Type</a></li>
44 <li><a href="#t_metadata">Metadata Type</a></li>
47 <li><a href="#t_derived">Derived Types</a>
49 <li><a href="#t_integer">Integer Type</a></li>
50 <li><a href="#t_array">Array Type</a></li>
51 <li><a href="#t_function">Function Type</a></li>
52 <li><a href="#t_pointer">Pointer Type</a></li>
53 <li><a href="#t_struct">Structure Type</a></li>
54 <li><a href="#t_pstruct">Packed Structure Type</a></li>
55 <li><a href="#t_vector">Vector Type</a></li>
56 <li><a href="#t_opaque">Opaque Type</a></li>
59 <li><a href="#t_uprefs">Type Up-references</a></li>
62 <li><a href="#constants">Constants</a>
64 <li><a href="#simpleconstants">Simple Constants</a></li>
65 <li><a href="#complexconstants">Complex Constants</a></li>
66 <li><a href="#globalconstants">Global Variable and Function Addresses</a></li>
67 <li><a href="#undefvalues">Undefined Values</a></li>
68 <li><a href="#constantexprs">Constant Expressions</a></li>
69 <li><a href="#metadata">Embedded Metadata</a></li>
72 <li><a href="#othervalues">Other Values</a>
74 <li><a href="#inlineasm">Inline Assembler Expressions</a></li>
77 <li><a href="#instref">Instruction Reference</a>
79 <li><a href="#terminators">Terminator Instructions</a>
81 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
82 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
83 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
84 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
85 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
86 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
89 <li><a href="#binaryops">Binary Operations</a>
91 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
92 <li><a href="#i_fadd">'<tt>fadd</tt>' Instruction</a></li>
93 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
94 <li><a href="#i_fsub">'<tt>fsub</tt>' Instruction</a></li>
95 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
96 <li><a href="#i_fmul">'<tt>fmul</tt>' Instruction</a></li>
97 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
98 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
99 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
100 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
101 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
102 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
105 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
107 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
108 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
109 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
110 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
111 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
112 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
115 <li><a href="#vectorops">Vector Operations</a>
117 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
118 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
119 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
122 <li><a href="#aggregateops">Aggregate Operations</a>
124 <li><a href="#i_extractvalue">'<tt>extractvalue</tt>' Instruction</a></li>
125 <li><a href="#i_insertvalue">'<tt>insertvalue</tt>' Instruction</a></li>
128 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
130 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
131 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
132 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
133 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
134 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
135 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
138 <li><a href="#convertops">Conversion Operations</a>
140 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
141 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
142 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
143 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
144 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
145 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
146 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
147 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
148 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
149 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
150 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
151 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
154 <li><a href="#otherops">Other Operations</a>
156 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
157 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
158 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
159 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
160 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
161 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
166 <li><a href="#intrinsics">Intrinsic Functions</a>
168 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
170 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
171 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
172 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
175 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
177 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
178 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
179 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
182 <li><a href="#int_codegen">Code Generator Intrinsics</a>
184 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
185 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
186 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
187 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
188 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
189 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
190 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
193 <li><a href="#int_libc">Standard C Library Intrinsics</a>
195 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
196 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
197 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
198 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
199 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
200 <li><a href="#int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a></li>
201 <li><a href="#int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a></li>
202 <li><a href="#int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a></li>
205 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
207 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
208 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
209 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
210 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
213 <li><a href="#int_overflow">Arithmetic with Overflow Intrinsics</a>
215 <li><a href="#int_sadd_overflow">'<tt>llvm.sadd.with.overflow.*</tt> Intrinsics</a></li>
216 <li><a href="#int_uadd_overflow">'<tt>llvm.uadd.with.overflow.*</tt> Intrinsics</a></li>
217 <li><a href="#int_ssub_overflow">'<tt>llvm.ssub.with.overflow.*</tt> Intrinsics</a></li>
218 <li><a href="#int_usub_overflow">'<tt>llvm.usub.with.overflow.*</tt> Intrinsics</a></li>
219 <li><a href="#int_smul_overflow">'<tt>llvm.smul.with.overflow.*</tt> Intrinsics</a></li>
220 <li><a href="#int_umul_overflow">'<tt>llvm.umul.with.overflow.*</tt> Intrinsics</a></li>
223 <li><a href="#int_debugger">Debugger intrinsics</a></li>
224 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
225 <li><a href="#int_trampoline">Trampoline Intrinsic</a>
227 <li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li>
230 <li><a href="#int_atomics">Atomic intrinsics</a>
232 <li><a href="#int_memory_barrier"><tt>llvm.memory_barrier</tt></a></li>
233 <li><a href="#int_atomic_cmp_swap"><tt>llvm.atomic.cmp.swap</tt></a></li>
234 <li><a href="#int_atomic_swap"><tt>llvm.atomic.swap</tt></a></li>
235 <li><a href="#int_atomic_load_add"><tt>llvm.atomic.load.add</tt></a></li>
236 <li><a href="#int_atomic_load_sub"><tt>llvm.atomic.load.sub</tt></a></li>
237 <li><a href="#int_atomic_load_and"><tt>llvm.atomic.load.and</tt></a></li>
238 <li><a href="#int_atomic_load_nand"><tt>llvm.atomic.load.nand</tt></a></li>
239 <li><a href="#int_atomic_load_or"><tt>llvm.atomic.load.or</tt></a></li>
240 <li><a href="#int_atomic_load_xor"><tt>llvm.atomic.load.xor</tt></a></li>
241 <li><a href="#int_atomic_load_max"><tt>llvm.atomic.load.max</tt></a></li>
242 <li><a href="#int_atomic_load_min"><tt>llvm.atomic.load.min</tt></a></li>
243 <li><a href="#int_atomic_load_umax"><tt>llvm.atomic.load.umax</tt></a></li>
244 <li><a href="#int_atomic_load_umin"><tt>llvm.atomic.load.umin</tt></a></li>
247 <li><a href="#int_general">General intrinsics</a>
249 <li><a href="#int_var_annotation">
250 '<tt>llvm.var.annotation</tt>' Intrinsic</a></li>
251 <li><a href="#int_annotation">
252 '<tt>llvm.annotation.*</tt>' Intrinsic</a></li>
253 <li><a href="#int_trap">
254 '<tt>llvm.trap</tt>' Intrinsic</a></li>
255 <li><a href="#int_stackprotector">
256 '<tt>llvm.stackprotector</tt>' Intrinsic</a></li>
263 <div class="doc_author">
264 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
265 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
268 <!-- *********************************************************************** -->
269 <div class="doc_section"> <a name="abstract">Abstract </a></div>
270 <!-- *********************************************************************** -->
272 <div class="doc_text">
273 <p>This document is a reference manual for the LLVM assembly language.
274 LLVM is a Static Single Assignment (SSA) based representation that provides
275 type safety, low-level operations, flexibility, and the capability of
276 representing 'all' high-level languages cleanly. It is the common code
277 representation used throughout all phases of the LLVM compilation
281 <!-- *********************************************************************** -->
282 <div class="doc_section"> <a name="introduction">Introduction</a> </div>
283 <!-- *********************************************************************** -->
285 <div class="doc_text">
287 <p>The LLVM code representation is designed to be used in three
288 different forms: as an in-memory compiler IR, as an on-disk bitcode
289 representation (suitable for fast loading by a Just-In-Time compiler),
290 and as a human readable assembly language representation. This allows
291 LLVM to provide a powerful intermediate representation for efficient
292 compiler transformations and analysis, while providing a natural means
293 to debug and visualize the transformations. The three different forms
294 of LLVM are all equivalent. This document describes the human readable
295 representation and notation.</p>
297 <p>The LLVM representation aims to be light-weight and low-level
298 while being expressive, typed, and extensible at the same time. It
299 aims to be a "universal IR" of sorts, by being at a low enough level
300 that high-level ideas may be cleanly mapped to it (similar to how
301 microprocessors are "universal IR's", allowing many source languages to
302 be mapped to them). By providing type information, LLVM can be used as
303 the target of optimizations: for example, through pointer analysis, it
304 can be proven that a C automatic variable is never accessed outside of
305 the current function... allowing it to be promoted to a simple SSA
306 value instead of a memory location.</p>
310 <!-- _______________________________________________________________________ -->
311 <div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
313 <div class="doc_text">
315 <p>It is important to note that this document describes 'well formed'
316 LLVM assembly language. There is a difference between what the parser
317 accepts and what is considered 'well formed'. For example, the
318 following instruction is syntactically okay, but not well formed:</p>
320 <div class="doc_code">
322 %x = <a href="#i_add">add</a> i32 1, %x
326 <p>...because the definition of <tt>%x</tt> does not dominate all of
327 its uses. The LLVM infrastructure provides a verification pass that may
328 be used to verify that an LLVM module is well formed. This pass is
329 automatically run by the parser after parsing input assembly and by
330 the optimizer before it outputs bitcode. The violations pointed out
331 by the verifier pass indicate bugs in transformation passes or input to
335 <!-- Describe the typesetting conventions here. -->
337 <!-- *********************************************************************** -->
338 <div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
339 <!-- *********************************************************************** -->
341 <div class="doc_text">
343 <p>LLVM identifiers come in two basic types: global and local. Global
344 identifiers (functions, global variables) begin with the @ character. Local
345 identifiers (register names, types) begin with the % character. Additionally,
346 there are three different formats for identifiers, for different purposes:</p>
349 <li>Named values are represented as a string of characters with their prefix.
350 For example, %foo, @DivisionByZero, %a.really.long.identifier. The actual
351 regular expression used is '<tt>[%@][a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
352 Identifiers which require other characters in their names can be surrounded
353 with quotes. Special characters may be escaped using "\xx" where xx is the
354 ASCII code for the character in hexadecimal. In this way, any character can
355 be used in a name value, even quotes themselves.
357 <li>Unnamed values are represented as an unsigned numeric value with their
358 prefix. For example, %12, @2, %44.</li>
360 <li>Constants, which are described in a <a href="#constants">section about
361 constants</a>, below.</li>
364 <p>LLVM requires that values start with a prefix for two reasons: Compilers
365 don't need to worry about name clashes with reserved words, and the set of
366 reserved words may be expanded in the future without penalty. Additionally,
367 unnamed identifiers allow a compiler to quickly come up with a temporary
368 variable without having to avoid symbol table conflicts.</p>
370 <p>Reserved words in LLVM are very similar to reserved words in other
371 languages. There are keywords for different opcodes
372 ('<tt><a href="#i_add">add</a></tt>',
373 '<tt><a href="#i_bitcast">bitcast</a></tt>',
374 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
375 href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
376 and others. These reserved words cannot conflict with variable names, because
377 none of them start with a prefix character ('%' or '@').</p>
379 <p>Here is an example of LLVM code to multiply the integer variable
380 '<tt>%X</tt>' by 8:</p>
384 <div class="doc_code">
386 %result = <a href="#i_mul">mul</a> i32 %X, 8
390 <p>After strength reduction:</p>
392 <div class="doc_code">
394 %result = <a href="#i_shl">shl</a> i32 %X, i8 3
398 <p>And the hard way:</p>
400 <div class="doc_code">
402 <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
403 <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
404 %result = <a href="#i_add">add</a> i32 %1, %1
408 <p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
409 important lexical features of LLVM:</p>
413 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
416 <li>Unnamed temporaries are created when the result of a computation is not
417 assigned to a named value.</li>
419 <li>Unnamed temporaries are numbered sequentially</li>
423 <p>...and it also shows a convention that we follow in this document. When
424 demonstrating instructions, we will follow an instruction with a comment that
425 defines the type and name of value produced. Comments are shown in italic
430 <!-- *********************************************************************** -->
431 <div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
432 <!-- *********************************************************************** -->
434 <!-- ======================================================================= -->
435 <div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
438 <div class="doc_text">
440 <p>LLVM programs are composed of "Module"s, each of which is a
441 translation unit of the input programs. Each module consists of
442 functions, global variables, and symbol table entries. Modules may be
443 combined together with the LLVM linker, which merges function (and
444 global variable) definitions, resolves forward declarations, and merges
445 symbol table entries. Here is an example of the "hello world" module:</p>
447 <div class="doc_code">
448 <pre><i>; Declare the string constant as a global constant...</i>
449 <a href="#identifiers">@.LC0</a> = <a href="#linkage_internal">internal</a> <a
450 href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00" <i>; [13 x i8]*</i>
452 <i>; External declaration of the puts function</i>
453 <a href="#functionstructure">declare</a> i32 @puts(i8 *) <i>; i32(i8 *)* </i>
455 <i>; Definition of main function</i>
456 define i32 @main() { <i>; i32()* </i>
457 <i>; Convert [13 x i8]* to i8 *...</i>
459 href="#i_getelementptr">getelementptr</a> [13 x i8]* @.LC0, i64 0, i64 0 <i>; i8 *</i>
461 <i>; Call puts function to write out the string to stdout...</i>
463 href="#i_call">call</a> i32 @puts(i8 * %cast210) <i>; i32</i>
465 href="#i_ret">ret</a> i32 0<br>}<br>
469 <p>This example is made up of a <a href="#globalvars">global variable</a>
470 named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
471 function, and a <a href="#functionstructure">function definition</a>
472 for "<tt>main</tt>".</p>
474 <p>In general, a module is made up of a list of global values,
475 where both functions and global variables are global values. Global values are
476 represented by a pointer to a memory location (in this case, a pointer to an
477 array of char, and a pointer to a function), and have one of the following <a
478 href="#linkage">linkage types</a>.</p>
482 <!-- ======================================================================= -->
483 <div class="doc_subsection">
484 <a name="linkage">Linkage Types</a>
487 <div class="doc_text">
490 All Global Variables and Functions have one of the following types of linkage:
495 <dt><tt><b><a name="linkage_private">private</a></b></tt>: </dt>
497 <dd>Global values with private linkage are only directly accessible by
498 objects in the current module. In particular, linking code into a module with
499 an private global value may cause the private to be renamed as necessary to
500 avoid collisions. Because the symbol is private to the module, all
501 references can be updated. This doesn't show up in any symbol table in the
505 <dt><tt><b><a name="linkage_internal">internal</a></b></tt>: </dt>
507 <dd> Similar to private, but the value shows as a local symbol (STB_LOCAL in
508 the case of ELF) in the object file. This corresponds to the notion of the
509 '<tt>static</tt>' keyword in C.
512 <dt><tt><b><a name="available_externally">available_externally</a></b></tt>:
515 <dd>Globals with "<tt>available_externally</tt>" linkage are never emitted
516 into the object file corresponding to the LLVM module. They exist to
517 allow inlining and other optimizations to take place given knowledge of the
518 definition of the global, which is known to be somewhere outside the module.
519 Globals with <tt>available_externally</tt> linkage are allowed to be discarded
520 at will, and are otherwise the same as <tt>linkonce_odr</tt>. This linkage
521 type is only allowed on definitions, not declarations.</dd>
523 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
525 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
526 the same name when linkage occurs. This is typically used to implement
527 inline functions, templates, or other code which must be generated in each
528 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
529 allowed to be discarded.
532 <dt><tt><b><a name="linkage_common">common</a></b></tt>: </dt>
534 <dd>"<tt>common</tt>" linkage is exactly the same as <tt>linkonce</tt>
535 linkage, except that unreferenced <tt>common</tt> globals may not be
536 discarded. This is used for globals that may be emitted in multiple
537 translation units, but that are not guaranteed to be emitted into every
538 translation unit that uses them. One example of this is tentative
539 definitions in C, such as "<tt>int X;</tt>" at global scope.
542 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
544 <dd>"<tt>weak</tt>" linkage is the same as <tt>common</tt> linkage, except
545 that some targets may choose to emit different assembly sequences for them
546 for target-dependent reasons. This is used for globals that are declared
547 "weak" in C source code.
550 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
552 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
553 pointer to array type. When two global variables with appending linkage are
554 linked together, the two global arrays are appended together. This is the
555 LLVM, typesafe, equivalent of having the system linker append together
556 "sections" with identical names when .o files are linked.
559 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
561 <dd>The semantics of this linkage follow the ELF object file model: the
562 symbol is weak until linked, if not linked, the symbol becomes null instead
563 of being an undefined reference.
566 <dt><tt><b><a name="linkage_linkonce">linkonce_odr</a></b></tt>: </dt>
567 <dt><tt><b><a name="linkage_weak">weak_odr</a></b></tt>: </dt>
568 <dd>Some languages allow differing globals to be merged, such as two
569 functions with different semantics. Other languages, such as <tt>C++</tt>,
570 ensure that only equivalent globals are ever merged (the "one definition
571 rule" - "ODR"). Such languages can use the <tt>linkonce_odr</tt>
572 and <tt>weak_odr</tt> linkage types to indicate that the global will only
573 be merged with equivalent globals. These linkage types are otherwise the
574 same as their non-<tt>odr</tt> versions.
577 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
579 <dd>If none of the above identifiers are used, the global is externally
580 visible, meaning that it participates in linkage and can be used to resolve
581 external symbol references.
586 The next two types of linkage are targeted for Microsoft Windows platform
587 only. They are designed to support importing (exporting) symbols from (to)
588 DLLs (Dynamic Link Libraries).
592 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
594 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
595 or variable via a global pointer to a pointer that is set up by the DLL
596 exporting the symbol. On Microsoft Windows targets, the pointer name is
597 formed by combining <code>__imp_</code> and the function or variable name.
600 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
602 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
603 pointer to a pointer in a DLL, so that it can be referenced with the
604 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
605 name is formed by combining <code>__imp_</code> and the function or variable
611 <p>For example, since the "<tt>.LC0</tt>"
612 variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
613 variable and was linked with this one, one of the two would be renamed,
614 preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
615 external (i.e., lacking any linkage declarations), they are accessible
616 outside of the current module.</p>
617 <p>It is illegal for a function <i>declaration</i>
618 to have any linkage type other than "externally visible", <tt>dllimport</tt>
619 or <tt>extern_weak</tt>.</p>
620 <p>Aliases can have only <tt>external</tt>, <tt>internal</tt>, <tt>weak</tt>
621 or <tt>weak_odr</tt> linkages.</p>
624 <!-- ======================================================================= -->
625 <div class="doc_subsection">
626 <a name="callingconv">Calling Conventions</a>
629 <div class="doc_text">
631 <p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
632 and <a href="#i_invoke">invokes</a> can all have an optional calling convention
633 specified for the call. The calling convention of any pair of dynamic
634 caller/callee must match, or the behavior of the program is undefined. The
635 following calling conventions are supported by LLVM, and more may be added in
639 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
641 <dd>This calling convention (the default if no other calling convention is
642 specified) matches the target C calling conventions. This calling convention
643 supports varargs function calls and tolerates some mismatch in the declared
644 prototype and implemented declaration of the function (as does normal C).
647 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
649 <dd>This calling convention attempts to make calls as fast as possible
650 (e.g. by passing things in registers). This calling convention allows the
651 target to use whatever tricks it wants to produce fast code for the target,
652 without having to conform to an externally specified ABI (Application Binary
653 Interface). Implementations of this convention should allow arbitrary
654 <a href="CodeGenerator.html#tailcallopt">tail call optimization</a> to be
655 supported. This calling convention does not support varargs and requires the
656 prototype of all callees to exactly match the prototype of the function
660 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
662 <dd>This calling convention attempts to make code in the caller as efficient
663 as possible under the assumption that the call is not commonly executed. As
664 such, these calls often preserve all registers so that the call does not break
665 any live ranges in the caller side. This calling convention does not support
666 varargs and requires the prototype of all callees to exactly match the
667 prototype of the function definition.
670 <dt><b>"<tt>cc <<em>n</em>></tt>" - Numbered convention</b>:</dt>
672 <dd>Any calling convention may be specified by number, allowing
673 target-specific calling conventions to be used. Target specific calling
674 conventions start at 64.
678 <p>More calling conventions can be added/defined on an as-needed basis, to
679 support pascal conventions or any other well-known target-independent
684 <!-- ======================================================================= -->
685 <div class="doc_subsection">
686 <a name="visibility">Visibility Styles</a>
689 <div class="doc_text">
692 All Global Variables and Functions have one of the following visibility styles:
696 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
698 <dd>On targets that use the ELF object file format, default visibility means
699 that the declaration is visible to other
700 modules and, in shared libraries, means that the declared entity may be
701 overridden. On Darwin, default visibility means that the declaration is
702 visible to other modules. Default visibility corresponds to "external
703 linkage" in the language.
706 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
708 <dd>Two declarations of an object with hidden visibility refer to the same
709 object if they are in the same shared object. Usually, hidden visibility
710 indicates that the symbol will not be placed into the dynamic symbol table,
711 so no other module (executable or shared library) can reference it
715 <dt><b>"<tt>protected</tt>" - Protected style</b>:</dt>
717 <dd>On ELF, protected visibility indicates that the symbol will be placed in
718 the dynamic symbol table, but that references within the defining module will
719 bind to the local symbol. That is, the symbol cannot be overridden by another
726 <!-- ======================================================================= -->
727 <div class="doc_subsection">
728 <a name="namedtypes">Named Types</a>
731 <div class="doc_text">
733 <p>LLVM IR allows you to specify name aliases for certain types. This can make
734 it easier to read the IR and make the IR more condensed (particularly when
735 recursive types are involved). An example of a name specification is:
738 <div class="doc_code">
740 %mytype = type { %mytype*, i32 }
744 <p>You may give a name to any <a href="#typesystem">type</a> except "<a
745 href="t_void">void</a>". Type name aliases may be used anywhere a type is
746 expected with the syntax "%mytype".</p>
748 <p>Note that type names are aliases for the structural type that they indicate,
749 and that you can therefore specify multiple names for the same type. This often
750 leads to confusing behavior when dumping out a .ll file. Since LLVM IR uses
751 structural typing, the name is not part of the type. When printing out LLVM IR,
752 the printer will pick <em>one name</em> to render all types of a particular
753 shape. This means that if you have code where two different source types end up
754 having the same LLVM type, that the dumper will sometimes print the "wrong" or
755 unexpected type. This is an important design point and isn't going to
760 <!-- ======================================================================= -->
761 <div class="doc_subsection">
762 <a name="globalvars">Global Variables</a>
765 <div class="doc_text">
767 <p>Global variables define regions of memory allocated at compilation time
768 instead of run-time. Global variables may optionally be initialized, may have
769 an explicit section to be placed in, and may have an optional explicit alignment
770 specified. A variable may be defined as "thread_local", which means that it
771 will not be shared by threads (each thread will have a separated copy of the
772 variable). A variable may be defined as a global "constant," which indicates
773 that the contents of the variable will <b>never</b> be modified (enabling better
774 optimization, allowing the global data to be placed in the read-only section of
775 an executable, etc). Note that variables that need runtime initialization
776 cannot be marked "constant" as there is a store to the variable.</p>
779 LLVM explicitly allows <em>declarations</em> of global variables to be marked
780 constant, even if the final definition of the global is not. This capability
781 can be used to enable slightly better optimization of the program, but requires
782 the language definition to guarantee that optimizations based on the
783 'constantness' are valid for the translation units that do not include the
787 <p>As SSA values, global variables define pointer values that are in
788 scope (i.e. they dominate) all basic blocks in the program. Global
789 variables always define a pointer to their "content" type because they
790 describe a region of memory, and all memory objects in LLVM are
791 accessed through pointers.</p>
793 <p>A global variable may be declared to reside in a target-specifc numbered
794 address space. For targets that support them, address spaces may affect how
795 optimizations are performed and/or what target instructions are used to access
796 the variable. The default address space is zero. The address space qualifier
797 must precede any other attributes.</p>
799 <p>LLVM allows an explicit section to be specified for globals. If the target
800 supports it, it will emit globals to the section specified.</p>
802 <p>An explicit alignment may be specified for a global. If not present, or if
803 the alignment is set to zero, the alignment of the global is set by the target
804 to whatever it feels convenient. If an explicit alignment is specified, the
805 global is forced to have at least that much alignment. All alignments must be
808 <p>For example, the following defines a global in a numbered address space with
809 an initializer, section, and alignment:</p>
811 <div class="doc_code">
813 @G = addrspace(5) constant float 1.0, section "foo", align 4
820 <!-- ======================================================================= -->
821 <div class="doc_subsection">
822 <a name="functionstructure">Functions</a>
825 <div class="doc_text">
827 <p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
828 an optional <a href="#linkage">linkage type</a>, an optional
829 <a href="#visibility">visibility style</a>, an optional
830 <a href="#callingconv">calling convention</a>, a return type, an optional
831 <a href="#paramattrs">parameter attribute</a> for the return type, a function
832 name, a (possibly empty) argument list (each with optional
833 <a href="#paramattrs">parameter attributes</a>), optional
834 <a href="#fnattrs">function attributes</a>, an optional section,
835 an optional alignment, an optional <a href="#gc">garbage collector name</a>,
836 an opening curly brace, a list of basic blocks, and a closing curly brace.
838 LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
839 optional <a href="#linkage">linkage type</a>, an optional
840 <a href="#visibility">visibility style</a>, an optional
841 <a href="#callingconv">calling convention</a>, a return type, an optional
842 <a href="#paramattrs">parameter attribute</a> for the return type, a function
843 name, a possibly empty list of arguments, an optional alignment, and an optional
844 <a href="#gc">garbage collector name</a>.</p>
846 <p>A function definition contains a list of basic blocks, forming the CFG
847 (Control Flow Graph) for
848 the function. Each basic block may optionally start with a label (giving the
849 basic block a symbol table entry), contains a list of instructions, and ends
850 with a <a href="#terminators">terminator</a> instruction (such as a branch or
851 function return).</p>
853 <p>The first basic block in a function is special in two ways: it is immediately
854 executed on entrance to the function, and it is not allowed to have predecessor
855 basic blocks (i.e. there can not be any branches to the entry block of a
856 function). Because the block can have no predecessors, it also cannot have any
857 <a href="#i_phi">PHI nodes</a>.</p>
859 <p>LLVM allows an explicit section to be specified for functions. If the target
860 supports it, it will emit functions to the section specified.</p>
862 <p>An explicit alignment may be specified for a function. If not present, or if
863 the alignment is set to zero, the alignment of the function is set by the target
864 to whatever it feels convenient. If an explicit alignment is specified, the
865 function is forced to have at least that much alignment. All alignments must be
870 <div class="doc_code">
872 define [<a href="#linkage">linkage</a>] [<a href="#visibility">visibility</a>]
873 [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>]
874 <ResultType> @<FunctionName> ([argument list])
875 [<a href="#fnattrs">fn Attrs</a>] [section "name"] [align N]
876 [<a href="#gc">gc</a>] { ... }
883 <!-- ======================================================================= -->
884 <div class="doc_subsection">
885 <a name="aliasstructure">Aliases</a>
887 <div class="doc_text">
888 <p>Aliases act as "second name" for the aliasee value (which can be either
889 function, global variable, another alias or bitcast of global value). Aliases
890 may have an optional <a href="#linkage">linkage type</a>, and an
891 optional <a href="#visibility">visibility style</a>.</p>
895 <div class="doc_code">
897 @<Name> = alias [Linkage] [Visibility] <AliaseeTy> @<Aliasee>
905 <!-- ======================================================================= -->
906 <div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
907 <div class="doc_text">
908 <p>The return type and each parameter of a function type may have a set of
909 <i>parameter attributes</i> associated with them. Parameter attributes are
910 used to communicate additional information about the result or parameters of
911 a function. Parameter attributes are considered to be part of the function,
912 not of the function type, so functions with different parameter attributes
913 can have the same function type.</p>
915 <p>Parameter attributes are simple keywords that follow the type specified. If
916 multiple parameter attributes are needed, they are space separated. For
919 <div class="doc_code">
921 declare i32 @printf(i8* noalias nocapture, ...)
922 declare i32 @atoi(i8 zeroext)
923 declare signext i8 @returns_signed_char()
927 <p>Note that any attributes for the function result (<tt>nounwind</tt>,
928 <tt>readonly</tt>) come immediately after the argument list.</p>
930 <p>Currently, only the following parameter attributes are defined:</p>
932 <dt><tt>zeroext</tt></dt>
933 <dd>This indicates to the code generator that the parameter or return value
934 should be zero-extended to a 32-bit value by the caller (for a parameter)
935 or the callee (for a return value).</dd>
937 <dt><tt>signext</tt></dt>
938 <dd>This indicates to the code generator that the parameter or return value
939 should be sign-extended to a 32-bit value by the caller (for a parameter)
940 or the callee (for a return value).</dd>
942 <dt><tt>inreg</tt></dt>
943 <dd>This indicates that this parameter or return value should be treated
944 in a special target-dependent fashion during while emitting code for a
945 function call or return (usually, by putting it in a register as opposed
946 to memory, though some targets use it to distinguish between two different
947 kinds of registers). Use of this attribute is target-specific.</dd>
949 <dt><tt><a name="byval">byval</a></tt></dt>
950 <dd>This indicates that the pointer parameter should really be passed by
951 value to the function. The attribute implies that a hidden copy of the
952 pointee is made between the caller and the callee, so the callee is unable
953 to modify the value in the callee. This attribute is only valid on LLVM
954 pointer arguments. It is generally used to pass structs and arrays by
955 value, but is also valid on pointers to scalars. The copy is considered to
956 belong to the caller not the callee (for example,
957 <tt><a href="#readonly">readonly</a></tt> functions should not write to
958 <tt>byval</tt> parameters). This is not a valid attribute for return
959 values. The byval attribute also supports specifying an alignment with the
960 align attribute. This has a target-specific effect on the code generator
961 that usually indicates a desired alignment for the synthesized stack
964 <dt><tt>sret</tt></dt>
965 <dd>This indicates that the pointer parameter specifies the address of a
966 structure that is the return value of the function in the source program.
967 This pointer must be guaranteed by the caller to be valid: loads and stores
968 to the structure may be assumed by the callee to not to trap. This may only
969 be applied to the first parameter. This is not a valid attribute for
972 <dt><tt>noalias</tt></dt>
973 <dd>This indicates that the pointer does not alias any global or any other
974 parameter. The caller is responsible for ensuring that this is the
975 case. On a function return value, <tt>noalias</tt> additionally indicates
976 that the pointer does not alias any other pointers visible to the
977 caller. For further details, please see the discussion of the NoAlias
979 <a href="http://llvm.org/docs/AliasAnalysis.html#MustMayNo">alias
982 <dt><tt>nocapture</tt></dt>
983 <dd>This indicates that the callee does not make any copies of the pointer
984 that outlive the callee itself. This is not a valid attribute for return
987 <dt><tt>nest</tt></dt>
988 <dd>This indicates that the pointer parameter can be excised using the
989 <a href="#int_trampoline">trampoline intrinsics</a>. This is not a valid
990 attribute for return values.</dd>
995 <!-- ======================================================================= -->
996 <div class="doc_subsection">
997 <a name="gc">Garbage Collector Names</a>
1000 <div class="doc_text">
1001 <p>Each function may specify a garbage collector name, which is simply a
1004 <div class="doc_code"><pre
1005 >define void @f() gc "name" { ...</pre></div>
1007 <p>The compiler declares the supported values of <i>name</i>. Specifying a
1008 collector which will cause the compiler to alter its output in order to support
1009 the named garbage collection algorithm.</p>
1012 <!-- ======================================================================= -->
1013 <div class="doc_subsection">
1014 <a name="fnattrs">Function Attributes</a>
1017 <div class="doc_text">
1019 <p>Function attributes are set to communicate additional information about
1020 a function. Function attributes are considered to be part of the function,
1021 not of the function type, so functions with different parameter attributes
1022 can have the same function type.</p>
1024 <p>Function attributes are simple keywords that follow the type specified. If
1025 multiple attributes are needed, they are space separated. For
1028 <div class="doc_code">
1030 define void @f() noinline { ... }
1031 define void @f() alwaysinline { ... }
1032 define void @f() alwaysinline optsize { ... }
1033 define void @f() optsize
1038 <dt><tt>alwaysinline</tt></dt>
1039 <dd>This attribute indicates that the inliner should attempt to inline this
1040 function into callers whenever possible, ignoring any active inlining size
1041 threshold for this caller.</dd>
1043 <dt><tt>noinline</tt></dt>
1044 <dd>This attribute indicates that the inliner should never inline this function
1045 in any situation. This attribute may not be used together with the
1046 <tt>alwaysinline</tt> attribute.</dd>
1048 <dt><tt>optsize</tt></dt>
1049 <dd>This attribute suggests that optimization passes and code generator passes
1050 make choices that keep the code size of this function low, and otherwise do
1051 optimizations specifically to reduce code size.</dd>
1053 <dt><tt>noreturn</tt></dt>
1054 <dd>This function attribute indicates that the function never returns normally.
1055 This produces undefined behavior at runtime if the function ever does
1056 dynamically return.</dd>
1058 <dt><tt>nounwind</tt></dt>
1059 <dd>This function attribute indicates that the function never returns with an
1060 unwind or exceptional control flow. If the function does unwind, its runtime
1061 behavior is undefined.</dd>
1063 <dt><tt>readnone</tt></dt>
1064 <dd>This attribute indicates that the function computes its result (or decides to
1065 unwind an exception) based strictly on its arguments, without dereferencing any
1066 pointer arguments or otherwise accessing any mutable state (e.g. memory, control
1067 registers, etc) visible to caller functions. It does not write through any
1068 pointer arguments (including <tt><a href="#byval">byval</a></tt> arguments) and
1069 never changes any state visible to callers. This means that it cannot unwind
1070 exceptions by calling the <tt>C++</tt> exception throwing methods, but could
1071 use the <tt>unwind</tt> instruction.</dd>
1073 <dt><tt><a name="readonly">readonly</a></tt></dt>
1074 <dd>This attribute indicates that the function does not write through any
1075 pointer arguments (including <tt><a href="#byval">byval</a></tt> arguments)
1076 or otherwise modify any state (e.g. memory, control registers, etc) visible to
1077 caller functions. It may dereference pointer arguments and read state that may
1078 be set in the caller. A readonly function always returns the same value (or
1079 unwinds an exception identically) when called with the same set of arguments
1080 and global state. It cannot unwind an exception by calling the <tt>C++</tt>
1081 exception throwing methods, but may use the <tt>unwind</tt> instruction.</dd>
1083 <dt><tt><a name="ssp">ssp</a></tt></dt>
1084 <dd>This attribute indicates that the function should emit a stack smashing
1085 protector. It is in the form of a "canary"—a random value placed on the
1086 stack before the local variables that's checked upon return from the function to
1087 see if it has been overwritten. A heuristic is used to determine if a function
1088 needs stack protectors or not.
1090 <br><br>If a function that has an <tt>ssp</tt> attribute is inlined into a function
1091 that doesn't have an <tt>ssp</tt> attribute, then the resulting function will
1092 have an <tt>ssp</tt> attribute.</dd>
1094 <dt><tt>sspreq</tt></dt>
1095 <dd>This attribute indicates that the function should <em>always</em> emit a
1096 stack smashing protector. This overrides the <tt><a href="#ssp">ssp</a></tt>
1099 If a function that has an <tt>sspreq</tt> attribute is inlined into a
1100 function that doesn't have an <tt>sspreq</tt> attribute or which has
1101 an <tt>ssp</tt> attribute, then the resulting function will have
1102 an <tt>sspreq</tt> attribute.</dd>
1104 <dt><tt>noredzone</tt></dt>
1105 <dd>This attribute indicates that the code generator should not use a
1106 red zone, even if the target-specific ABI normally permits it.
1109 <dt><tt>noimplicitfloat</tt></dt>
1110 <dd>This attributes disables implicit floating point instructions.</dd>
1112 <dt><tt>naked</tt></dt>
1113 <dd>This attribute disables prologue / epilogue emission for the function.
1114 This can have very system-specific consequences.</dd>
1120 <!-- ======================================================================= -->
1121 <div class="doc_subsection">
1122 <a name="moduleasm">Module-Level Inline Assembly</a>
1125 <div class="doc_text">
1127 Modules may contain "module-level inline asm" blocks, which corresponds to the
1128 GCC "file scope inline asm" blocks. These blocks are internally concatenated by
1129 LLVM and treated as a single unit, but may be separated in the .ll file if
1130 desired. The syntax is very simple:
1133 <div class="doc_code">
1135 module asm "inline asm code goes here"
1136 module asm "more can go here"
1140 <p>The strings can contain any character by escaping non-printable characters.
1141 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
1146 The inline asm code is simply printed to the machine code .s file when
1147 assembly code is generated.
1151 <!-- ======================================================================= -->
1152 <div class="doc_subsection">
1153 <a name="datalayout">Data Layout</a>
1156 <div class="doc_text">
1157 <p>A module may specify a target specific data layout string that specifies how
1158 data is to be laid out in memory. The syntax for the data layout is simply:</p>
1159 <pre> target datalayout = "<i>layout specification</i>"</pre>
1160 <p>The <i>layout specification</i> consists of a list of specifications
1161 separated by the minus sign character ('-'). Each specification starts with a
1162 letter and may include other information after the letter to define some
1163 aspect of the data layout. The specifications accepted are as follows: </p>
1166 <dd>Specifies that the target lays out data in big-endian form. That is, the
1167 bits with the most significance have the lowest address location.</dd>
1169 <dd>Specifies that the target lays out data in little-endian form. That is,
1170 the bits with the least significance have the lowest address location.</dd>
1171 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1172 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
1173 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
1174 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
1176 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1177 <dd>This specifies the alignment for an integer type of a given bit
1178 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
1179 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1180 <dd>This specifies the alignment for a vector type of a given bit
1182 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1183 <dd>This specifies the alignment for a floating point type of a given bit
1184 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
1186 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1187 <dd>This specifies the alignment for an aggregate type of a given bit
1189 <dt><tt>s<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1190 <dd>This specifies the alignment for a stack object of a given bit
1193 <p>When constructing the data layout for a given target, LLVM starts with a
1194 default set of specifications which are then (possibly) overriden by the
1195 specifications in the <tt>datalayout</tt> keyword. The default specifications
1196 are given in this list:</p>
1198 <li><tt>E</tt> - big endian</li>
1199 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
1200 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
1201 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
1202 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
1203 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
1204 <li><tt>i64:32:64</tt> - i64 has ABI alignment of 32-bits but preferred
1205 alignment of 64-bits</li>
1206 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
1207 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
1208 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
1209 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
1210 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
1211 <li><tt>s0:64:64</tt> - stack objects are 64-bit aligned</li>
1213 <p>When LLVM is determining the alignment for a given type, it uses the
1214 following rules:</p>
1216 <li>If the type sought is an exact match for one of the specifications, that
1217 specification is used.</li>
1218 <li>If no match is found, and the type sought is an integer type, then the
1219 smallest integer type that is larger than the bitwidth of the sought type is
1220 used. If none of the specifications are larger than the bitwidth then the the
1221 largest integer type is used. For example, given the default specifications
1222 above, the i7 type will use the alignment of i8 (next largest) while both
1223 i65 and i256 will use the alignment of i64 (largest specified).</li>
1224 <li>If no match is found, and the type sought is a vector type, then the
1225 largest vector type that is smaller than the sought vector type will be used
1226 as a fall back. This happens because <128 x double> can be implemented
1227 in terms of 64 <2 x double>, for example.</li>
1231 <!-- *********************************************************************** -->
1232 <div class="doc_section"> <a name="typesystem">Type System</a> </div>
1233 <!-- *********************************************************************** -->
1235 <div class="doc_text">
1237 <p>The LLVM type system is one of the most important features of the
1238 intermediate representation. Being typed enables a number of
1239 optimizations to be performed on the intermediate representation directly,
1240 without having to do
1241 extra analyses on the side before the transformation. A strong type
1242 system makes it easier to read the generated code and enables novel
1243 analyses and transformations that are not feasible to perform on normal
1244 three address code representations.</p>
1248 <!-- ======================================================================= -->
1249 <div class="doc_subsection"> <a name="t_classifications">Type
1250 Classifications</a> </div>
1251 <div class="doc_text">
1252 <p>The types fall into a few useful
1253 classifications:</p>
1255 <table border="1" cellspacing="0" cellpadding="4">
1257 <tr><th>Classification</th><th>Types</th></tr>
1259 <td><a href="#t_integer">integer</a></td>
1260 <td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
1263 <td><a href="#t_floating">floating point</a></td>
1264 <td><tt>float, double, x86_fp80, fp128, ppc_fp128</tt></td>
1267 <td><a name="t_firstclass">first class</a></td>
1268 <td><a href="#t_integer">integer</a>,
1269 <a href="#t_floating">floating point</a>,
1270 <a href="#t_pointer">pointer</a>,
1271 <a href="#t_vector">vector</a>,
1272 <a href="#t_struct">structure</a>,
1273 <a href="#t_array">array</a>,
1274 <a href="#t_label">label</a>,
1275 <a href="#t_metadata">metadata</a>.
1279 <td><a href="#t_primitive">primitive</a></td>
1280 <td><a href="#t_label">label</a>,
1281 <a href="#t_void">void</a>,
1282 <a href="#t_floating">floating point</a>,
1283 <a href="#t_metadata">metadata</a>.</td>
1286 <td><a href="#t_derived">derived</a></td>
1287 <td><a href="#t_integer">integer</a>,
1288 <a href="#t_array">array</a>,
1289 <a href="#t_function">function</a>,
1290 <a href="#t_pointer">pointer</a>,
1291 <a href="#t_struct">structure</a>,
1292 <a href="#t_pstruct">packed structure</a>,
1293 <a href="#t_vector">vector</a>,
1294 <a href="#t_opaque">opaque</a>.
1300 <p>The <a href="#t_firstclass">first class</a> types are perhaps the
1301 most important. Values of these types are the only ones which can be
1302 produced by instructions, passed as arguments, or used as operands to
1306 <!-- ======================================================================= -->
1307 <div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
1309 <div class="doc_text">
1310 <p>The primitive types are the fundamental building blocks of the LLVM
1315 <!-- _______________________________________________________________________ -->
1316 <div class="doc_subsubsection"> <a name="t_floating">Floating Point Types</a> </div>
1318 <div class="doc_text">
1321 <tr><th>Type</th><th>Description</th></tr>
1322 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
1323 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
1324 <tr><td><tt>fp128</tt></td><td>128-bit floating point value (112-bit mantissa)</td></tr>
1325 <tr><td><tt>x86_fp80</tt></td><td>80-bit floating point value (X87)</td></tr>
1326 <tr><td><tt>ppc_fp128</tt></td><td>128-bit floating point value (two 64-bits)</td></tr>
1331 <!-- _______________________________________________________________________ -->
1332 <div class="doc_subsubsection"> <a name="t_void">Void Type</a> </div>
1334 <div class="doc_text">
1336 <p>The void type does not represent any value and has no size.</p>
1345 <!-- _______________________________________________________________________ -->
1346 <div class="doc_subsubsection"> <a name="t_label">Label Type</a> </div>
1348 <div class="doc_text">
1350 <p>The label type represents code labels.</p>
1359 <!-- _______________________________________________________________________ -->
1360 <div class="doc_subsubsection"> <a name="t_metadata">Metadata Type</a> </div>
1362 <div class="doc_text">
1364 <p>The metadata type represents embedded metadata. The only derived type that
1365 may contain metadata is <tt>metadata*</tt> or a function type that returns or
1366 takes metadata typed parameters, but not pointer to metadata types.</p>
1376 <!-- ======================================================================= -->
1377 <div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
1379 <div class="doc_text">
1381 <p>The real power in LLVM comes from the derived types in the system.
1382 This is what allows a programmer to represent arrays, functions,
1383 pointers, and other useful types. Note that these derived types may be
1384 recursive: For example, it is possible to have a two dimensional array.</p>
1388 <!-- _______________________________________________________________________ -->
1389 <div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>
1391 <div class="doc_text">
1394 <p>The integer type is a very simple derived type that simply specifies an
1395 arbitrary bit width for the integer type desired. Any bit width from 1 bit to
1396 2^23-1 (about 8 million) can be specified.</p>
1404 <p>The number of bits the integer will occupy is specified by the <tt>N</tt>
1408 <table class="layout">
1410 <td class="left"><tt>i1</tt></td>
1411 <td class="left">a single-bit integer.</td>
1414 <td class="left"><tt>i32</tt></td>
1415 <td class="left">a 32-bit integer.</td>
1418 <td class="left"><tt>i1942652</tt></td>
1419 <td class="left">a really big integer of over 1 million bits.</td>
1423 <p>Note that the code generator does not yet support large integer types
1424 to be used as function return types. The specific limit on how large a
1425 return type the code generator can currently handle is target-dependent;
1426 currently it's often 64 bits for 32-bit targets and 128 bits for 64-bit
1431 <!-- _______________________________________________________________________ -->
1432 <div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
1434 <div class="doc_text">
1438 <p>The array type is a very simple derived type that arranges elements
1439 sequentially in memory. The array type requires a size (number of
1440 elements) and an underlying data type.</p>
1445 [<# elements> x <elementtype>]
1448 <p>The number of elements is a constant integer value; elementtype may
1449 be any type with a size.</p>
1452 <table class="layout">
1454 <td class="left"><tt>[40 x i32]</tt></td>
1455 <td class="left">Array of 40 32-bit integer values.</td>
1458 <td class="left"><tt>[41 x i32]</tt></td>
1459 <td class="left">Array of 41 32-bit integer values.</td>
1462 <td class="left"><tt>[4 x i8]</tt></td>
1463 <td class="left">Array of 4 8-bit integer values.</td>
1466 <p>Here are some examples of multidimensional arrays:</p>
1467 <table class="layout">
1469 <td class="left"><tt>[3 x [4 x i32]]</tt></td>
1470 <td class="left">3x4 array of 32-bit integer values.</td>
1473 <td class="left"><tt>[12 x [10 x float]]</tt></td>
1474 <td class="left">12x10 array of single precision floating point values.</td>
1477 <td class="left"><tt>[2 x [3 x [4 x i16]]]</tt></td>
1478 <td class="left">2x3x4 array of 16-bit integer values.</td>
1482 <p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1483 length array. Normally, accesses past the end of an array are undefined in
1484 LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1485 As a special case, however, zero length arrays are recognized to be variable
1486 length. This allows implementation of 'pascal style arrays' with the LLVM
1487 type "{ i32, [0 x float]}", for example.</p>
1489 <p>Note that the code generator does not yet support large aggregate types
1490 to be used as function return types. The specific limit on how large an
1491 aggregate return type the code generator can currently handle is
1492 target-dependent, and also dependent on the aggregate element types.</p>
1496 <!-- _______________________________________________________________________ -->
1497 <div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
1498 <div class="doc_text">
1502 <p>The function type can be thought of as a function signature. It
1503 consists of a return type and a list of formal parameter types. The
1504 return type of a function type is a scalar type, a void type, or a struct type.
1505 If the return type is a struct type then all struct elements must be of first
1506 class types, and the struct must have at least one element.</p>
1511 <returntype list> (<parameter list>)
1514 <p>...where '<tt><parameter list></tt>' is a comma-separated list of type
1515 specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
1516 which indicates that the function takes a variable number of arguments.
1517 Variable argument functions can access their arguments with the <a
1518 href="#int_varargs">variable argument handling intrinsic</a> functions.
1519 '<tt><returntype list></tt>' is a comma-separated list of
1520 <a href="#t_firstclass">first class</a> type specifiers.</p>
1523 <table class="layout">
1525 <td class="left"><tt>i32 (i32)</tt></td>
1526 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
1528 </tr><tr class="layout">
1529 <td class="left"><tt>float (i16 signext, i32 *) *
1531 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1532 an <tt>i16</tt> that should be sign extended and a
1533 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
1536 </tr><tr class="layout">
1537 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1538 <td class="left">A vararg function that takes at least one
1539 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
1540 which returns an integer. This is the signature for <tt>printf</tt> in
1543 </tr><tr class="layout">
1544 <td class="left"><tt>{i32, i32} (i32)</tt></td>
1545 <td class="left">A function taking an <tt>i32</tt>, returning two
1546 <tt>i32</tt> values as an aggregate of type <tt>{ i32, i32 }</tt>
1552 <!-- _______________________________________________________________________ -->
1553 <div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
1554 <div class="doc_text">
1556 <p>The structure type is used to represent a collection of data members
1557 together in memory. The packing of the field types is defined to match
1558 the ABI of the underlying processor. The elements of a structure may
1559 be any type that has a size.</p>
1560 <p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1561 and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1562 field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1565 <pre> { <type list> }<br></pre>
1567 <table class="layout">
1569 <td class="left"><tt>{ i32, i32, i32 }</tt></td>
1570 <td class="left">A triple of three <tt>i32</tt> values</td>
1571 </tr><tr class="layout">
1572 <td class="left"><tt>{ float, i32 (i32) * }</tt></td>
1573 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1574 second element is a <a href="#t_pointer">pointer</a> to a
1575 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1576 an <tt>i32</tt>.</td>
1580 <p>Note that the code generator does not yet support large aggregate types
1581 to be used as function return types. The specific limit on how large an
1582 aggregate return type the code generator can currently handle is
1583 target-dependent, and also dependent on the aggregate element types.</p>
1587 <!-- _______________________________________________________________________ -->
1588 <div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1590 <div class="doc_text">
1592 <p>The packed structure type is used to represent a collection of data members
1593 together in memory. There is no padding between fields. Further, the alignment
1594 of a packed structure is 1 byte. The elements of a packed structure may
1595 be any type that has a size.</p>
1596 <p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1597 and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1598 field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1601 <pre> < { <type list> } > <br></pre>
1603 <table class="layout">
1605 <td class="left"><tt>< { i32, i32, i32 } ></tt></td>
1606 <td class="left">A triple of three <tt>i32</tt> values</td>
1607 </tr><tr class="layout">
1609 <tt>< { float, i32 (i32)* } ></tt></td>
1610 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1611 second element is a <a href="#t_pointer">pointer</a> to a
1612 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1613 an <tt>i32</tt>.</td>
1618 <!-- _______________________________________________________________________ -->
1619 <div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
1620 <div class="doc_text">
1622 <p>As in many languages, the pointer type represents a pointer or
1623 reference to another object, which must live in memory. Pointer types may have
1624 an optional address space attribute defining the target-specific numbered
1625 address space where the pointed-to object resides. The default address space is
1628 <p>Note that LLVM does not permit pointers to void (<tt>void*</tt>) nor does
1629 it permit pointers to labels (<tt>label*</tt>). Use <tt>i8*</tt> instead.</p>
1632 <pre> <type> *<br></pre>
1634 <table class="layout">
1636 <td class="left"><tt>[4 x i32]*</tt></td>
1637 <td class="left">A <a href="#t_pointer">pointer</a> to <a
1638 href="#t_array">array</a> of four <tt>i32</tt> values.</td>
1641 <td class="left"><tt>i32 (i32 *) *</tt></td>
1642 <td class="left"> A <a href="#t_pointer">pointer</a> to a <a
1643 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1647 <td class="left"><tt>i32 addrspace(5)*</tt></td>
1648 <td class="left">A <a href="#t_pointer">pointer</a> to an <tt>i32</tt> value
1649 that resides in address space #5.</td>
1654 <!-- _______________________________________________________________________ -->
1655 <div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
1656 <div class="doc_text">
1660 <p>A vector type is a simple derived type that represents a vector
1661 of elements. Vector types are used when multiple primitive data
1662 are operated in parallel using a single instruction (SIMD).
1663 A vector type requires a size (number of
1664 elements) and an underlying primitive data type. Vectors must have a power
1665 of two length (1, 2, 4, 8, 16 ...). Vector types are
1666 considered <a href="#t_firstclass">first class</a>.</p>
1671 < <# elements> x <elementtype> >
1674 <p>The number of elements is a constant integer value; elementtype may
1675 be any integer or floating point type.</p>
1679 <table class="layout">
1681 <td class="left"><tt><4 x i32></tt></td>
1682 <td class="left">Vector of 4 32-bit integer values.</td>
1685 <td class="left"><tt><8 x float></tt></td>
1686 <td class="left">Vector of 8 32-bit floating-point values.</td>
1689 <td class="left"><tt><2 x i64></tt></td>
1690 <td class="left">Vector of 2 64-bit integer values.</td>
1694 <p>Note that the code generator does not yet support large vector types
1695 to be used as function return types. The specific limit on how large a
1696 vector return type codegen can currently handle is target-dependent;
1697 currently it's often a few times longer than a hardware vector register.</p>
1701 <!-- _______________________________________________________________________ -->
1702 <div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1703 <div class="doc_text">
1707 <p>Opaque types are used to represent unknown types in the system. This
1708 corresponds (for example) to the C notion of a forward declared structure type.
1709 In LLVM, opaque types can eventually be resolved to any type (not just a
1710 structure type).</p>
1720 <table class="layout">
1722 <td class="left"><tt>opaque</tt></td>
1723 <td class="left">An opaque type.</td>
1728 <!-- ======================================================================= -->
1729 <div class="doc_subsection">
1730 <a name="t_uprefs">Type Up-references</a>
1733 <div class="doc_text">
1736 An "up reference" allows you to refer to a lexically enclosing type without
1737 requiring it to have a name. For instance, a structure declaration may contain a
1738 pointer to any of the types it is lexically a member of. Example of up
1739 references (with their equivalent as named type declarations) include:</p>
1742 { \2 * } %x = type { %x* }
1743 { \2 }* %y = type { %y }*
1748 An up reference is needed by the asmprinter for printing out cyclic types when
1749 there is no declared name for a type in the cycle. Because the asmprinter does
1750 not want to print out an infinite type string, it needs a syntax to handle
1751 recursive types that have no names (all names are optional in llvm IR).
1760 The level is the count of the lexical type that is being referred to.
1765 <table class="layout">
1767 <td class="left"><tt>\1*</tt></td>
1768 <td class="left">Self-referential pointer.</td>
1771 <td class="left"><tt>{ { \3*, i8 }, i32 }</tt></td>
1772 <td class="left">Recursive structure where the upref refers to the out-most
1779 <!-- *********************************************************************** -->
1780 <div class="doc_section"> <a name="constants">Constants</a> </div>
1781 <!-- *********************************************************************** -->
1783 <div class="doc_text">
1785 <p>LLVM has several different basic types of constants. This section describes
1786 them all and their syntax.</p>
1790 <!-- ======================================================================= -->
1791 <div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
1793 <div class="doc_text">
1796 <dt><b>Boolean constants</b></dt>
1798 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
1799 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
1802 <dt><b>Integer constants</b></dt>
1804 <dd>Standard integers (such as '4') are constants of the <a
1805 href="#t_integer">integer</a> type. Negative numbers may be used with
1809 <dt><b>Floating point constants</b></dt>
1811 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1812 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
1813 notation (see below). The assembler requires the exact decimal value of
1814 a floating-point constant. For example, the assembler accepts 1.25 but
1815 rejects 1.3 because 1.3 is a repeating decimal in binary. Floating point
1816 constants must have a <a href="#t_floating">floating point</a> type. </dd>
1818 <dt><b>Null pointer constants</b></dt>
1820 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
1821 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1825 <p>The one non-intuitive notation for constants is the hexadecimal form
1826 of floating point constants. For example, the form '<tt>double
1827 0x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
1828 4.5e+15</tt>'. The only time hexadecimal floating point constants are required
1829 (and the only time that they are generated by the disassembler) is when a
1830 floating point constant must be emitted but it cannot be represented as a
1831 decimal floating point number in a reasonable number of digits. For example,
1832 NaN's, infinities, and other
1833 special values are represented in their IEEE hexadecimal format so that
1834 assembly and disassembly do not cause any bits to change in the constants.</p>
1835 <p>When using the hexadecimal form, constants of types float and double are
1836 represented using the 16-digit form shown above (which matches the IEEE754
1837 representation for double); float values must, however, be exactly representable
1838 as IEE754 single precision.
1839 Hexadecimal format is always used for long
1840 double, and there are three forms of long double. The 80-bit
1841 format used by x86 is represented as <tt>0xK</tt>
1842 followed by 20 hexadecimal digits.
1843 The 128-bit format used by PowerPC (two adjacent doubles) is represented
1844 by <tt>0xM</tt> followed by 32 hexadecimal digits. The IEEE 128-bit
1845 format is represented
1846 by <tt>0xL</tt> followed by 32 hexadecimal digits; no currently supported
1847 target uses this format. Long doubles will only work if they match
1848 the long double format on your target. All hexadecimal formats are big-endian
1849 (sign bit at the left).</p>
1852 <!-- ======================================================================= -->
1853 <div class="doc_subsection">
1854 <a name="aggregateconstants"> <!-- old anchor -->
1855 <a name="complexconstants">Complex Constants</a></a>
1858 <div class="doc_text">
1859 <p>Complex constants are a (potentially recursive) combination of simple
1860 constants and smaller complex constants.</p>
1863 <dt><b>Structure constants</b></dt>
1865 <dd>Structure constants are represented with notation similar to structure
1866 type definitions (a comma separated list of elements, surrounded by braces
1867 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* @G }</tt>",
1868 where "<tt>@G</tt>" is declared as "<tt>@G = external global i32</tt>". Structure constants
1869 must have <a href="#t_struct">structure type</a>, and the number and
1870 types of elements must match those specified by the type.
1873 <dt><b>Array constants</b></dt>
1875 <dd>Array constants are represented with notation similar to array type
1876 definitions (a comma separated list of elements, surrounded by square brackets
1877 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
1878 constants must have <a href="#t_array">array type</a>, and the number and
1879 types of elements must match those specified by the type.
1882 <dt><b>Vector constants</b></dt>
1884 <dd>Vector constants are represented with notation similar to vector type
1885 definitions (a comma separated list of elements, surrounded by
1886 less-than/greater-than's (<tt><></tt>)). For example: "<tt>< i32 42,
1887 i32 11, i32 74, i32 100 ></tt>". Vector constants must have <a
1888 href="#t_vector">vector type</a>, and the number and types of elements must
1889 match those specified by the type.
1892 <dt><b>Zero initialization</b></dt>
1894 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1895 value to zero of <em>any</em> type, including scalar and aggregate types.
1896 This is often used to avoid having to print large zero initializers (e.g. for
1897 large arrays) and is always exactly equivalent to using explicit zero
1901 <dt><b>Metadata node</b></dt>
1903 <dd>A metadata node is a structure-like constant with
1904 <a href="#t_metadata">metadata type</a>. For example:
1905 "<tt>metadata !{ i32 0, metadata !"test" }</tt>". Unlike other constants
1906 that are meant to be interpreted as part of the instruction stream, metadata
1907 is a place to attach additional information such as debug info.
1913 <!-- ======================================================================= -->
1914 <div class="doc_subsection">
1915 <a name="globalconstants">Global Variable and Function Addresses</a>
1918 <div class="doc_text">
1920 <p>The addresses of <a href="#globalvars">global variables</a> and <a
1921 href="#functionstructure">functions</a> are always implicitly valid (link-time)
1922 constants. These constants are explicitly referenced when the <a
1923 href="#identifiers">identifier for the global</a> is used and always have <a
1924 href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1927 <div class="doc_code">
1931 @Z = global [2 x i32*] [ i32* @X, i32* @Y ]
1937 <!-- ======================================================================= -->
1938 <div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
1939 <div class="doc_text">
1940 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
1941 no specific value. Undefined values may be of any type and be used anywhere
1942 a constant is permitted.</p>
1944 <p>Undefined values indicate to the compiler that the program is well defined
1945 no matter what value is used, giving the compiler more freedom to optimize.
1949 <!-- ======================================================================= -->
1950 <div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1953 <div class="doc_text">
1955 <p>Constant expressions are used to allow expressions involving other constants
1956 to be used as constants. Constant expressions may be of any <a
1957 href="#t_firstclass">first class</a> type and may involve any LLVM operation
1958 that does not have side effects (e.g. load and call are not supported). The
1959 following is the syntax for constant expressions:</p>
1962 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1963 <dd>Truncate a constant to another type. The bit size of CST must be larger
1964 than the bit size of TYPE. Both types must be integers.</dd>
1966 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1967 <dd>Zero extend a constant to another type. The bit size of CST must be
1968 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1970 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1971 <dd>Sign extend a constant to another type. The bit size of CST must be
1972 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1974 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1975 <dd>Truncate a floating point constant to another floating point type. The
1976 size of CST must be larger than the size of TYPE. Both types must be
1977 floating point.</dd>
1979 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1980 <dd>Floating point extend a constant to another type. The size of CST must be
1981 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1983 <dt><b><tt>fptoui ( CST to TYPE )</tt></b></dt>
1984 <dd>Convert a floating point constant to the corresponding unsigned integer
1985 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1986 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1987 of the same number of elements. If the value won't fit in the integer type,
1988 the results are undefined.</dd>
1990 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
1991 <dd>Convert a floating point constant to the corresponding signed integer
1992 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1993 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1994 of the same number of elements. If the value won't fit in the integer type,
1995 the results are undefined.</dd>
1997 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
1998 <dd>Convert an unsigned integer constant to the corresponding floating point
1999 constant. TYPE must be a scalar or vector floating point type. CST must be of
2000 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
2001 of the same number of elements. If the value won't fit in the floating point
2002 type, the results are undefined.</dd>
2004 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
2005 <dd>Convert a signed integer constant to the corresponding floating point
2006 constant. TYPE must be a scalar or vector floating point type. CST must be of
2007 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
2008 of the same number of elements. If the value won't fit in the floating point
2009 type, the results are undefined.</dd>
2011 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
2012 <dd>Convert a pointer typed constant to the corresponding integer constant
2013 TYPE must be an integer type. CST must be of pointer type. The CST value is
2014 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
2016 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
2017 <dd>Convert a integer constant to a pointer constant. TYPE must be a
2018 pointer type. CST must be of integer type. The CST value is zero extended,
2019 truncated, or unchanged to make it fit in a pointer size. This one is
2020 <i>really</i> dangerous!</dd>
2022 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
2023 <dd>Convert a constant, CST, to another TYPE. The constraints of the operands
2024 are the same as those for the <a href="#i_bitcast">bitcast
2025 instruction</a>.</dd>
2027 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
2029 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
2030 constants. As with the <a href="#i_getelementptr">getelementptr</a>
2031 instruction, the index list may have zero or more indexes, which are required
2032 to make sense for the type of "CSTPTR".</dd>
2034 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
2036 <dd>Perform the <a href="#i_select">select operation</a> on
2039 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
2040 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
2042 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
2043 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
2045 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
2047 <dd>Perform the <a href="#i_extractelement">extractelement
2048 operation</a> on constants.</dd>
2050 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
2052 <dd>Perform the <a href="#i_insertelement">insertelement
2053 operation</a> on constants.</dd>
2056 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
2058 <dd>Perform the <a href="#i_shufflevector">shufflevector
2059 operation</a> on constants.</dd>
2061 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
2063 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
2064 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
2065 binary</a> operations. The constraints on operands are the same as those for
2066 the corresponding instruction (e.g. no bitwise operations on floating point
2067 values are allowed).</dd>
2071 <!-- ======================================================================= -->
2072 <div class="doc_subsection"><a name="metadata">Embedded Metadata</a>
2075 <div class="doc_text">
2077 <p>Embedded metadata provides a way to attach arbitrary data to the
2078 instruction stream without affecting the behaviour of the program. There are
2079 two metadata primitives, strings and nodes. All metadata has the
2080 <tt>metadata</tt> type and is identified in syntax by a preceding exclamation
2081 point ('<tt>!</tt>').
2084 <p>A metadata string is a string surrounded by double quotes. It can contain
2085 any character by escaping non-printable characters with "\xx" where "xx" is
2086 the two digit hex code. For example: "<tt>!"test\00"</tt>".
2089 <p>Metadata nodes are represented with notation similar to structure constants
2090 (a comma separated list of elements, surrounded by braces and preceeded by an
2091 exclamation point). For example: "<tt>!{ metadata !"test\00", i32 10}</tt>".
2094 <p>A metadata node will attempt to track changes to the values it holds. In
2095 the event that a value is deleted, it will be replaced with a typeless
2096 "<tt>null</tt>", such as "<tt>metadata !{null, i32 10}</tt>".</p>
2098 <p>Optimizations may rely on metadata to provide additional information about
2099 the program that isn't available in the instructions, or that isn't easily
2100 computable. Similarly, the code generator may expect a certain metadata format
2101 to be used to express debugging information.</p>
2104 <!-- *********************************************************************** -->
2105 <div class="doc_section"> <a name="othervalues">Other Values</a> </div>
2106 <!-- *********************************************************************** -->
2108 <!-- ======================================================================= -->
2109 <div class="doc_subsection">
2110 <a name="inlineasm">Inline Assembler Expressions</a>
2113 <div class="doc_text">
2116 LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
2117 Module-Level Inline Assembly</a>) through the use of a special value. This
2118 value represents the inline assembler as a string (containing the instructions
2119 to emit), a list of operand constraints (stored as a string), and a flag that
2120 indicates whether or not the inline asm expression has side effects. An example
2121 inline assembler expression is:
2124 <div class="doc_code">
2126 i32 (i32) asm "bswap $0", "=r,r"
2131 Inline assembler expressions may <b>only</b> be used as the callee operand of
2132 a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
2135 <div class="doc_code">
2137 %X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
2142 Inline asms with side effects not visible in the constraint list must be marked
2143 as having side effects. This is done through the use of the
2144 '<tt>sideeffect</tt>' keyword, like so:
2147 <div class="doc_code">
2149 call void asm sideeffect "eieio", ""()
2153 <p>TODO: The format of the asm and constraints string still need to be
2154 documented here. Constraints on what can be done (e.g. duplication, moving, etc
2155 need to be documented). This is probably best done by reference to another
2156 document that covers inline asm from a holistic perspective.
2161 <!-- *********************************************************************** -->
2162 <div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
2163 <!-- *********************************************************************** -->
2165 <div class="doc_text">
2167 <p>The LLVM instruction set consists of several different
2168 classifications of instructions: <a href="#terminators">terminator
2169 instructions</a>, <a href="#binaryops">binary instructions</a>,
2170 <a href="#bitwiseops">bitwise binary instructions</a>, <a
2171 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
2172 instructions</a>.</p>
2176 <!-- ======================================================================= -->
2177 <div class="doc_subsection"> <a name="terminators">Terminator
2178 Instructions</a> </div>
2180 <div class="doc_text">
2182 <p>As mentioned <a href="#functionstructure">previously</a>, every
2183 basic block in a program ends with a "Terminator" instruction, which
2184 indicates which block should be executed after the current block is
2185 finished. These terminator instructions typically yield a '<tt>void</tt>'
2186 value: they produce control flow, not values (the one exception being
2187 the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
2188 <p>There are six different terminator instructions: the '<a
2189 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
2190 instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
2191 the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
2192 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
2193 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
2197 <!-- _______________________________________________________________________ -->
2198 <div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
2199 Instruction</a> </div>
2200 <div class="doc_text">
2203 ret <type> <value> <i>; Return a value from a non-void function</i>
2204 ret void <i>; Return from void function</i>
2209 <p>The '<tt>ret</tt>' instruction is used to return control flow (and
2210 optionally a value) from a function back to the caller.</p>
2211 <p>There are two forms of the '<tt>ret</tt>' instruction: one that
2212 returns a value and then causes control flow, and one that just causes
2213 control flow to occur.</p>
2217 <p>The '<tt>ret</tt>' instruction optionally accepts a single argument,
2218 the return value. The type of the return value must be a
2219 '<a href="#t_firstclass">first class</a>' type.</p>
2221 <p>A function is not <a href="#wellformed">well formed</a> if
2222 it it has a non-void return type and contains a '<tt>ret</tt>'
2223 instruction with no return value or a return value with a type that
2224 does not match its type, or if it has a void return type and contains
2225 a '<tt>ret</tt>' instruction with a return value.</p>
2229 <p>When the '<tt>ret</tt>' instruction is executed, control flow
2230 returns back to the calling function's context. If the caller is a "<a
2231 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
2232 the instruction after the call. If the caller was an "<a
2233 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
2234 at the beginning of the "normal" destination block. If the instruction
2235 returns a value, that value shall set the call or invoke instruction's
2241 ret i32 5 <i>; Return an integer value of 5</i>
2242 ret void <i>; Return from a void function</i>
2243 ret { i32, i8 } { i32 4, i8 2 } <i>; Return a struct of values 4 and 2</i>
2246 <p>Note that the code generator does not yet fully support large
2247 return values. The specific sizes that are currently supported are
2248 dependent on the target. For integers, on 32-bit targets the limit
2249 is often 64 bits, and on 64-bit targets the limit is often 128 bits.
2250 For aggregate types, the current limits are dependent on the element
2251 types; for example targets are often limited to 2 total integer
2252 elements and 2 total floating-point elements.</p>
2255 <!-- _______________________________________________________________________ -->
2256 <div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
2257 <div class="doc_text">
2259 <pre> br i1 <cond>, label <iftrue>, label <iffalse><br> br label <dest> <i>; Unconditional branch</i>
2262 <p>The '<tt>br</tt>' instruction is used to cause control flow to
2263 transfer to a different basic block in the current function. There are
2264 two forms of this instruction, corresponding to a conditional branch
2265 and an unconditional branch.</p>
2267 <p>The conditional branch form of the '<tt>br</tt>' instruction takes a
2268 single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
2269 unconditional form of the '<tt>br</tt>' instruction takes a single
2270 '<tt>label</tt>' value as a target.</p>
2272 <p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
2273 argument is evaluated. If the value is <tt>true</tt>, control flows
2274 to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
2275 control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
2277 <pre>Test:<br> %cond = <a href="#i_icmp">icmp</a> eq i32 %a, %b<br> br i1 %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br> <a
2278 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
2280 <!-- _______________________________________________________________________ -->
2281 <div class="doc_subsubsection">
2282 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
2285 <div class="doc_text">
2289 switch <intty> <value>, label <defaultdest> [ <intty> <val>, label <dest> ... ]
2294 <p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
2295 several different places. It is a generalization of the '<tt>br</tt>'
2296 instruction, allowing a branch to occur to one of many possible
2302 <p>The '<tt>switch</tt>' instruction uses three parameters: an integer
2303 comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
2304 an array of pairs of comparison value constants and '<tt>label</tt>'s. The
2305 table is not allowed to contain duplicate constant entries.</p>
2309 <p>The <tt>switch</tt> instruction specifies a table of values and
2310 destinations. When the '<tt>switch</tt>' instruction is executed, this
2311 table is searched for the given value. If the value is found, control flow is
2312 transfered to the corresponding destination; otherwise, control flow is
2313 transfered to the default destination.</p>
2315 <h5>Implementation:</h5>
2317 <p>Depending on properties of the target machine and the particular
2318 <tt>switch</tt> instruction, this instruction may be code generated in different
2319 ways. For example, it could be generated as a series of chained conditional
2320 branches or with a lookup table.</p>
2325 <i>; Emulate a conditional br instruction</i>
2326 %Val = <a href="#i_zext">zext</a> i1 %value to i32
2327 switch i32 %Val, label %truedest [ i32 0, label %falsedest ]
2329 <i>; Emulate an unconditional br instruction</i>
2330 switch i32 0, label %dest [ ]
2332 <i>; Implement a jump table:</i>
2333 switch i32 %val, label %otherwise [ i32 0, label %onzero
2335 i32 2, label %ontwo ]
2339 <!-- _______________________________________________________________________ -->
2340 <div class="doc_subsubsection">
2341 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
2344 <div class="doc_text">
2349 <result> = invoke [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>] <ptr to function ty> <function ptr val>(<function args>) [<a href="#fnattrs">fn attrs</a>]
2350 to label <normal label> unwind label <exception label>
2355 <p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
2356 function, with the possibility of control flow transfer to either the
2357 '<tt>normal</tt>' label or the
2358 '<tt>exception</tt>' label. If the callee function returns with the
2359 "<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
2360 "normal" label. If the callee (or any indirect callees) returns with the "<a
2361 href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
2362 continued at the dynamically nearest "exception" label.</p>
2366 <p>This instruction requires several arguments:</p>
2370 The optional "cconv" marker indicates which <a href="#callingconv">calling
2371 convention</a> the call should use. If none is specified, the call defaults
2372 to using C calling conventions.
2375 <li>The optional <a href="#paramattrs">Parameter Attributes</a> list for
2376 return values. Only '<tt>zeroext</tt>', '<tt>signext</tt>',
2377 and '<tt>inreg</tt>' attributes are valid here.</li>
2379 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
2380 function value being invoked. In most cases, this is a direct function
2381 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
2382 an arbitrary pointer to function value.
2385 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
2386 function to be invoked. </li>
2388 <li>'<tt>function args</tt>': argument list whose types match the function
2389 signature argument types. If the function signature indicates the function
2390 accepts a variable number of arguments, the extra arguments can be
2393 <li>'<tt>normal label</tt>': the label reached when the called function
2394 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
2396 <li>'<tt>exception label</tt>': the label reached when a callee returns with
2397 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
2399 <li>The optional <a href="#fnattrs">function attributes</a> list. Only
2400 '<tt>noreturn</tt>', '<tt>nounwind</tt>', '<tt>readonly</tt>' and
2401 '<tt>readnone</tt>' attributes are valid here.</li>
2406 <p>This instruction is designed to operate as a standard '<tt><a
2407 href="#i_call">call</a></tt>' instruction in most regards. The primary
2408 difference is that it establishes an association with a label, which is used by
2409 the runtime library to unwind the stack.</p>
2411 <p>This instruction is used in languages with destructors to ensure that proper
2412 cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
2413 exception. Additionally, this is important for implementation of
2414 '<tt>catch</tt>' clauses in high-level languages that support them.</p>
2416 <p>For the purposes of the SSA form, the definition of the value
2417 returned by the '<tt>invoke</tt>' instruction is deemed to occur on
2418 the edge from the current block to the "normal" label. If the callee
2419 unwinds then no return value is available.</p>
2423 %retval = invoke i32 @Test(i32 15) to label %Continue
2424 unwind label %TestCleanup <i>; {i32}:retval set</i>
2425 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Testfnptr(i32 15) to label %Continue
2426 unwind label %TestCleanup <i>; {i32}:retval set</i>
2431 <!-- _______________________________________________________________________ -->
2433 <div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
2434 Instruction</a> </div>
2436 <div class="doc_text">
2445 <p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
2446 at the first callee in the dynamic call stack which used an <a
2447 href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
2448 primarily used to implement exception handling.</p>
2452 <p>The '<tt>unwind</tt>' instruction causes execution of the current function to
2453 immediately halt. The dynamic call stack is then searched for the first <a
2454 href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
2455 execution continues at the "exceptional" destination block specified by the
2456 <tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
2457 dynamic call chain, undefined behavior results.</p>
2460 <!-- _______________________________________________________________________ -->
2462 <div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
2463 Instruction</a> </div>
2465 <div class="doc_text">
2474 <p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
2475 instruction is used to inform the optimizer that a particular portion of the
2476 code is not reachable. This can be used to indicate that the code after a
2477 no-return function cannot be reached, and other facts.</p>
2481 <p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
2486 <!-- ======================================================================= -->
2487 <div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
2488 <div class="doc_text">
2489 <p>Binary operators are used to do most of the computation in a
2490 program. They require two operands of the same type, execute an operation on them, and
2491 produce a single value. The operands might represent
2492 multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
2493 The result value has the same type as its operands.</p>
2494 <p>There are several different binary operators:</p>
2496 <!-- _______________________________________________________________________ -->
2497 <div class="doc_subsubsection">
2498 <a name="i_add">'<tt>add</tt>' Instruction</a>
2501 <div class="doc_text">
2506 <result> = add <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2511 <p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
2515 <p>The two arguments to the '<tt>add</tt>' instruction must be <a
2516 href="#t_integer">integer</a> or
2517 <a href="#t_vector">vector</a> of integer values. Both arguments must
2518 have identical types.</p>
2522 <p>The value produced is the integer sum of the two operands.</p>
2524 <p>If the sum has unsigned overflow, the result returned is the
2525 mathematical result modulo 2<sup>n</sup>, where n is the bit width of
2528 <p>Because LLVM integers use a two's complement representation, this
2529 instruction is appropriate for both signed and unsigned integers.</p>
2534 <result> = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
2537 <!-- _______________________________________________________________________ -->
2538 <div class="doc_subsubsection">
2539 <a name="i_fadd">'<tt>fadd</tt>' Instruction</a>
2542 <div class="doc_text">
2547 <result> = fadd <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2552 <p>The '<tt>fadd</tt>' instruction returns the sum of its two operands.</p>
2556 <p>The two arguments to the '<tt>fadd</tt>' instruction must be
2557 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a> of
2558 floating point values. Both arguments must have identical types.</p>
2562 <p>The value produced is the floating point sum of the two operands.</p>
2567 <result> = fadd float 4.0, %var <i>; yields {float}:result = 4.0 + %var</i>
2570 <!-- _______________________________________________________________________ -->
2571 <div class="doc_subsubsection">
2572 <a name="i_sub">'<tt>sub</tt>' Instruction</a>
2575 <div class="doc_text">
2580 <result> = sub <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2585 <p>The '<tt>sub</tt>' instruction returns the difference of its two
2588 <p>Note that the '<tt>sub</tt>' instruction is used to represent the
2589 '<tt>neg</tt>' instruction present in most other intermediate
2590 representations.</p>
2594 <p>The two arguments to the '<tt>sub</tt>' instruction must be <a
2595 href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of
2596 integer values. Both arguments must have identical types.</p>
2600 <p>The value produced is the integer difference of the two operands.</p>
2602 <p>If the difference has unsigned overflow, the result returned is the
2603 mathematical result modulo 2<sup>n</sup>, where n is the bit width of
2606 <p>Because LLVM integers use a two's complement representation, this
2607 instruction is appropriate for both signed and unsigned integers.</p>
2611 <result> = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
2612 <result> = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
2616 <!-- _______________________________________________________________________ -->
2617 <div class="doc_subsubsection">
2618 <a name="i_fsub">'<tt>fsub</tt>' Instruction</a>
2621 <div class="doc_text">
2626 <result> = fsub <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2631 <p>The '<tt>fsub</tt>' instruction returns the difference of its two
2634 <p>Note that the '<tt>fsub</tt>' instruction is used to represent the
2635 '<tt>fneg</tt>' instruction present in most other intermediate
2636 representations.</p>
2640 <p>The two arguments to the '<tt>fsub</tt>' instruction must be <a
2641 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a>
2642 of floating point values. Both arguments must have identical types.</p>
2646 <p>The value produced is the floating point difference of the two operands.</p>
2650 <result> = fsub float 4.0, %var <i>; yields {float}:result = 4.0 - %var</i>
2651 <result> = fsub float -0.0, %val <i>; yields {float}:result = -%var</i>
2655 <!-- _______________________________________________________________________ -->
2656 <div class="doc_subsubsection">
2657 <a name="i_mul">'<tt>mul</tt>' Instruction</a>
2660 <div class="doc_text">
2663 <pre> <result> = mul <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2666 <p>The '<tt>mul</tt>' instruction returns the product of its two
2671 <p>The two arguments to the '<tt>mul</tt>' instruction must be <a
2672 href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2673 values. Both arguments must have identical types.</p>
2677 <p>The value produced is the integer product of the two operands.</p>
2679 <p>If the result of the multiplication has unsigned overflow,
2680 the result returned is the mathematical result modulo
2681 2<sup>n</sup>, where n is the bit width of the result.</p>
2682 <p>Because LLVM integers use a two's complement representation, and the
2683 result is the same width as the operands, this instruction returns the
2684 correct result for both signed and unsigned integers. If a full product
2685 (e.g. <tt>i32</tt>x<tt>i32</tt>-><tt>i64</tt>) is needed, the operands
2686 should be sign-extended or zero-extended as appropriate to the
2687 width of the full product.</p>
2689 <pre> <result> = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
2693 <!-- _______________________________________________________________________ -->
2694 <div class="doc_subsubsection">
2695 <a name="i_fmul">'<tt>fmul</tt>' Instruction</a>
2698 <div class="doc_text">
2701 <pre> <result> = fmul <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2704 <p>The '<tt>fmul</tt>' instruction returns the product of its two
2709 <p>The two arguments to the '<tt>fmul</tt>' instruction must be
2710 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a>
2711 of floating point values. Both arguments must have identical types.</p>
2715 <p>The value produced is the floating point product of the two operands.</p>
2718 <pre> <result> = fmul float 4.0, %var <i>; yields {float}:result = 4.0 * %var</i>
2722 <!-- _______________________________________________________________________ -->
2723 <div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
2725 <div class="doc_text">
2727 <pre> <result> = udiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2730 <p>The '<tt>udiv</tt>' instruction returns the quotient of its two
2735 <p>The two arguments to the '<tt>udiv</tt>' instruction must be
2736 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2737 values. Both arguments must have identical types.</p>
2741 <p>The value produced is the unsigned integer quotient of the two operands.</p>
2742 <p>Note that unsigned integer division and signed integer division are distinct
2743 operations; for signed integer division, use '<tt>sdiv</tt>'.</p>
2744 <p>Division by zero leads to undefined behavior.</p>
2746 <pre> <result> = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2749 <!-- _______________________________________________________________________ -->
2750 <div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
2752 <div class="doc_text">
2755 <result> = sdiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2760 <p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
2765 <p>The two arguments to the '<tt>sdiv</tt>' instruction must be
2766 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2767 values. Both arguments must have identical types.</p>
2770 <p>The value produced is the signed integer quotient of the two operands rounded towards zero.</p>
2771 <p>Note that signed integer division and unsigned integer division are distinct
2772 operations; for unsigned integer division, use '<tt>udiv</tt>'.</p>
2773 <p>Division by zero leads to undefined behavior. Overflow also leads to
2774 undefined behavior; this is a rare case, but can occur, for example,
2775 by doing a 32-bit division of -2147483648 by -1.</p>
2777 <pre> <result> = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2780 <!-- _______________________________________________________________________ -->
2781 <div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
2782 Instruction</a> </div>
2783 <div class="doc_text">
2786 <result> = fdiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2790 <p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
2795 <p>The two arguments to the '<tt>fdiv</tt>' instruction must be
2796 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a>
2797 of floating point values. Both arguments must have identical types.</p>
2801 <p>The value produced is the floating point quotient of the two operands.</p>
2806 <result> = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
2810 <!-- _______________________________________________________________________ -->
2811 <div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
2813 <div class="doc_text">
2815 <pre> <result> = urem <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2818 <p>The '<tt>urem</tt>' instruction returns the remainder from the
2819 unsigned division of its two arguments.</p>
2821 <p>The two arguments to the '<tt>urem</tt>' instruction must be
2822 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2823 values. Both arguments must have identical types.</p>
2825 <p>This instruction returns the unsigned integer <i>remainder</i> of a division.
2826 This instruction always performs an unsigned division to get the remainder.</p>
2827 <p>Note that unsigned integer remainder and signed integer remainder are
2828 distinct operations; for signed integer remainder, use '<tt>srem</tt>'.</p>
2829 <p>Taking the remainder of a division by zero leads to undefined behavior.</p>
2831 <pre> <result> = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2835 <!-- _______________________________________________________________________ -->
2836 <div class="doc_subsubsection">
2837 <a name="i_srem">'<tt>srem</tt>' Instruction</a>
2840 <div class="doc_text">
2845 <result> = srem <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2850 <p>The '<tt>srem</tt>' instruction returns the remainder from the
2851 signed division of its two operands. This instruction can also take
2852 <a href="#t_vector">vector</a> versions of the values in which case
2853 the elements must be integers.</p>
2857 <p>The two arguments to the '<tt>srem</tt>' instruction must be
2858 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2859 values. Both arguments must have identical types.</p>
2863 <p>This instruction returns the <i>remainder</i> of a division (where the result
2864 has the same sign as the dividend, <tt>op1</tt>), not the <i>modulo</i>
2865 operator (where the result has the same sign as the divisor, <tt>op2</tt>) of
2866 a value. For more information about the difference, see <a
2867 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
2868 Math Forum</a>. For a table of how this is implemented in various languages,
2869 please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
2870 Wikipedia: modulo operation</a>.</p>
2871 <p>Note that signed integer remainder and unsigned integer remainder are
2872 distinct operations; for unsigned integer remainder, use '<tt>urem</tt>'.</p>
2873 <p>Taking the remainder of a division by zero leads to undefined behavior.
2874 Overflow also leads to undefined behavior; this is a rare case, but can occur,
2875 for example, by taking the remainder of a 32-bit division of -2147483648 by -1.
2876 (The remainder doesn't actually overflow, but this rule lets srem be
2877 implemented using instructions that return both the result of the division
2878 and the remainder.)</p>
2880 <pre> <result> = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2884 <!-- _______________________________________________________________________ -->
2885 <div class="doc_subsubsection">
2886 <a name="i_frem">'<tt>frem</tt>' Instruction</a> </div>
2888 <div class="doc_text">
2891 <pre> <result> = frem <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2894 <p>The '<tt>frem</tt>' instruction returns the remainder from the
2895 division of its two operands.</p>
2897 <p>The two arguments to the '<tt>frem</tt>' instruction must be
2898 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a>
2899 of floating point values. Both arguments must have identical types.</p>
2903 <p>This instruction returns the <i>remainder</i> of a division.
2904 The remainder has the same sign as the dividend.</p>
2909 <result> = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
2913 <!-- ======================================================================= -->
2914 <div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2915 Operations</a> </div>
2916 <div class="doc_text">
2917 <p>Bitwise binary operators are used to do various forms of
2918 bit-twiddling in a program. They are generally very efficient
2919 instructions and can commonly be strength reduced from other
2920 instructions. They require two operands of the same type, execute an operation on them,
2921 and produce a single value. The resulting value is the same type as its operands.</p>
2924 <!-- _______________________________________________________________________ -->
2925 <div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2926 Instruction</a> </div>
2927 <div class="doc_text">
2929 <pre> <result> = shl <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2934 <p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2935 the left a specified number of bits.</p>
2939 <p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2940 href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2941 type. '<tt>op2</tt>' is treated as an unsigned value.</p>
2945 <p>The value produced is <tt>op1</tt> * 2<sup><tt>op2</tt></sup> mod 2<sup>n</sup>,
2946 where n is the width of the result. If <tt>op2</tt> is (statically or dynamically) negative or
2947 equal to or larger than the number of bits in <tt>op1</tt>, the result is undefined.
2948 If the arguments are vectors, each vector element of <tt>op1</tt> is shifted by the
2949 corresponding shift amount in <tt>op2</tt>.</p>
2951 <h5>Example:</h5><pre>
2952 <result> = shl i32 4, %var <i>; yields {i32}: 4 << %var</i>
2953 <result> = shl i32 4, 2 <i>; yields {i32}: 16</i>
2954 <result> = shl i32 1, 10 <i>; yields {i32}: 1024</i>
2955 <result> = shl i32 1, 32 <i>; undefined</i>
2956 <result> = shl <2 x i32> < i32 1, i32 1>, < i32 1, i32 2> <i>; yields: result=<2 x i32> < i32 2, i32 4></i>
2959 <!-- _______________________________________________________________________ -->
2960 <div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2961 Instruction</a> </div>
2962 <div class="doc_text">
2964 <pre> <result> = lshr <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2968 <p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2969 operand shifted to the right a specified number of bits with zero fill.</p>
2972 <p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2973 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2974 type. '<tt>op2</tt>' is treated as an unsigned value.</p>
2978 <p>This instruction always performs a logical shift right operation. The most
2979 significant bits of the result will be filled with zero bits after the
2980 shift. If <tt>op2</tt> is (statically or dynamically) equal to or larger than
2981 the number of bits in <tt>op1</tt>, the result is undefined. If the arguments are
2982 vectors, each vector element of <tt>op1</tt> is shifted by the corresponding shift
2983 amount in <tt>op2</tt>.</p>
2987 <result> = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2988 <result> = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2989 <result> = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2990 <result> = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
2991 <result> = lshr i32 1, 32 <i>; undefined</i>
2992 <result> = lshr <2 x i32> < i32 -2, i32 4>, < i32 1, i32 2> <i>; yields: result=<2 x i32> < i32 0x7FFFFFFF, i32 1></i>
2996 <!-- _______________________________________________________________________ -->
2997 <div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2998 Instruction</a> </div>
2999 <div class="doc_text">
3002 <pre> <result> = ashr <ty> <op1>, <op2> <i>; yields {ty}:result</i>
3006 <p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
3007 operand shifted to the right a specified number of bits with sign extension.</p>
3010 <p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
3011 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3012 type. '<tt>op2</tt>' is treated as an unsigned value.</p>
3015 <p>This instruction always performs an arithmetic shift right operation,
3016 The most significant bits of the result will be filled with the sign bit
3017 of <tt>op1</tt>. If <tt>op2</tt> is (statically or dynamically) equal to or
3018 larger than the number of bits in <tt>op1</tt>, the result is undefined. If the
3019 arguments are vectors, each vector element of <tt>op1</tt> is shifted by the
3020 corresponding shift amount in <tt>op2</tt>.</p>
3024 <result> = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
3025 <result> = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
3026 <result> = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
3027 <result> = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
3028 <result> = ashr i32 1, 32 <i>; undefined</i>
3029 <result> = ashr <2 x i32> < i32 -2, i32 4>, < i32 1, i32 3> <i>; yields: result=<2 x i32> < i32 -1, i32 0></i>
3033 <!-- _______________________________________________________________________ -->
3034 <div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
3035 Instruction</a> </div>
3037 <div class="doc_text">
3042 <result> = and <ty> <op1>, <op2> <i>; yields {ty}:result</i>
3047 <p>The '<tt>and</tt>' instruction returns the bitwise logical and of
3048 its two operands.</p>
3052 <p>The two arguments to the '<tt>and</tt>' instruction must be
3053 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3054 values. Both arguments must have identical types.</p>
3057 <p>The truth table used for the '<tt>and</tt>' instruction is:</p>
3060 <table border="1" cellspacing="0" cellpadding="4">
3092 <result> = and i32 4, %var <i>; yields {i32}:result = 4 & %var</i>
3093 <result> = and i32 15, 40 <i>; yields {i32}:result = 8</i>
3094 <result> = and i32 4, 8 <i>; yields {i32}:result = 0</i>
3097 <!-- _______________________________________________________________________ -->
3098 <div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
3099 <div class="doc_text">
3101 <pre> <result> = or <ty> <op1>, <op2> <i>; yields {ty}:result</i>
3104 <p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
3105 or of its two operands.</p>
3108 <p>The two arguments to the '<tt>or</tt>' instruction must be
3109 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3110 values. Both arguments must have identical types.</p>
3112 <p>The truth table used for the '<tt>or</tt>' instruction is:</p>
3115 <table border="1" cellspacing="0" cellpadding="4">
3146 <pre> <result> = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
3147 <result> = or i32 15, 40 <i>; yields {i32}:result = 47</i>
3148 <result> = or i32 4, 8 <i>; yields {i32}:result = 12</i>
3151 <!-- _______________________________________________________________________ -->
3152 <div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
3153 Instruction</a> </div>
3154 <div class="doc_text">
3156 <pre> <result> = xor <ty> <op1>, <op2> <i>; yields {ty}:result</i>
3159 <p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
3160 or of its two operands. The <tt>xor</tt> is used to implement the
3161 "one's complement" operation, which is the "~" operator in C.</p>
3163 <p>The two arguments to the '<tt>xor</tt>' instruction must be
3164 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
3165 values. Both arguments must have identical types.</p>
3169 <p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
3172 <table border="1" cellspacing="0" cellpadding="4">
3204 <pre> <result> = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
3205 <result> = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
3206 <result> = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
3207 <result> = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
3211 <!-- ======================================================================= -->
3212 <div class="doc_subsection">
3213 <a name="vectorops">Vector Operations</a>
3216 <div class="doc_text">
3218 <p>LLVM supports several instructions to represent vector operations in a
3219 target-independent manner. These instructions cover the element-access and
3220 vector-specific operations needed to process vectors effectively. While LLVM
3221 does directly support these vector operations, many sophisticated algorithms
3222 will want to use target-specific intrinsics to take full advantage of a specific
3227 <!-- _______________________________________________________________________ -->
3228 <div class="doc_subsubsection">
3229 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
3232 <div class="doc_text">
3237 <result> = extractelement <n x <ty>> <val>, i32 <idx> <i>; yields <ty></i>
3243 The '<tt>extractelement</tt>' instruction extracts a single scalar
3244 element from a vector at a specified index.
3251 The first operand of an '<tt>extractelement</tt>' instruction is a
3252 value of <a href="#t_vector">vector</a> type. The second operand is
3253 an index indicating the position from which to extract the element.
3254 The index may be a variable.</p>
3259 The result is a scalar of the same type as the element type of
3260 <tt>val</tt>. Its value is the value at position <tt>idx</tt> of
3261 <tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
3262 results are undefined.
3268 %result = extractelement <4 x i32> %vec, i32 0 <i>; yields i32</i>
3273 <!-- _______________________________________________________________________ -->
3274 <div class="doc_subsubsection">
3275 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
3278 <div class="doc_text">
3283 <result> = insertelement <n x <ty>> <val>, <ty> <elt>, i32 <idx> <i>; yields <n x <ty>></i>
3289 The '<tt>insertelement</tt>' instruction inserts a scalar
3290 element into a vector at a specified index.
3297 The first operand of an '<tt>insertelement</tt>' instruction is a
3298 value of <a href="#t_vector">vector</a> type. The second operand is a
3299 scalar value whose type must equal the element type of the first
3300 operand. The third operand is an index indicating the position at
3301 which to insert the value. The index may be a variable.</p>
3306 The result is a vector of the same type as <tt>val</tt>. Its
3307 element values are those of <tt>val</tt> except at position
3308 <tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
3309 exceeds the length of <tt>val</tt>, the results are undefined.
3315 %result = insertelement <4 x i32> %vec, i32 1, i32 0 <i>; yields <4 x i32></i>
3319 <!-- _______________________________________________________________________ -->
3320 <div class="doc_subsubsection">
3321 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
3324 <div class="doc_text">
3329 <result> = shufflevector <n x <ty>> <v1>, <n x <ty>> <v2>, <m x i32> <mask> <i>; yields <m x <ty>></i>
3335 The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
3336 from two input vectors, returning a vector with the same element type as
3337 the input and length that is the same as the shuffle mask.
3343 The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
3344 with types that match each other. The third argument is a shuffle mask whose
3345 element type is always 'i32'. The result of the instruction is a vector whose
3346 length is the same as the shuffle mask and whose element type is the same as
3347 the element type of the first two operands.
3351 The shuffle mask operand is required to be a constant vector with either
3352 constant integer or undef values.
3358 The elements of the two input vectors are numbered from left to right across
3359 both of the vectors. The shuffle mask operand specifies, for each element of
3360 the result vector, which element of the two input vectors the result element
3361 gets. The element selector may be undef (meaning "don't care") and the second
3362 operand may be undef if performing a shuffle from only one vector.
3368 %result = shufflevector <4 x i32> %v1, <4 x i32> %v2,
3369 <4 x i32> <i32 0, i32 4, i32 1, i32 5> <i>; yields <4 x i32></i>
3370 %result = shufflevector <4 x i32> %v1, <4 x i32> undef,
3371 <4 x i32> <i32 0, i32 1, i32 2, i32 3> <i>; yields <4 x i32></i> - Identity shuffle.
3372 %result = shufflevector <8 x i32> %v1, <8 x i32> undef,
3373 <4 x i32> <i32 0, i32 1, i32 2, i32 3> <i>; yields <4 x i32></i>
3374 %result = shufflevector <4 x i32> %v1, <4 x i32> %v2,
3375 <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7 > <i>; yields <8 x i32></i>
3380 <!-- ======================================================================= -->
3381 <div class="doc_subsection">
3382 <a name="aggregateops">Aggregate Operations</a>
3385 <div class="doc_text">
3387 <p>LLVM supports several instructions for working with aggregate values.
3392 <!-- _______________________________________________________________________ -->
3393 <div class="doc_subsubsection">
3394 <a name="i_extractvalue">'<tt>extractvalue</tt>' Instruction</a>
3397 <div class="doc_text">
3402 <result> = extractvalue <aggregate type> <val>, <idx>{, <idx>}*
3408 The '<tt>extractvalue</tt>' instruction extracts the value of a struct field
3409 or array element from an aggregate value.
3416 The first operand of an '<tt>extractvalue</tt>' instruction is a
3417 value of <a href="#t_struct">struct</a> or <a href="#t_array">array</a>
3418 type. The operands are constant indices to specify which value to extract
3419 in a similar manner as indices in a
3420 '<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.
3426 The result is the value at the position in the aggregate specified by
3433 %result = extractvalue {i32, float} %agg, 0 <i>; yields i32</i>
3438 <!-- _______________________________________________________________________ -->
3439 <div class="doc_subsubsection">
3440 <a name="i_insertvalue">'<tt>insertvalue</tt>' Instruction</a>
3443 <div class="doc_text">
3448 <result> = insertvalue <aggregate type> <val>, <ty> <val>, <idx> <i>; yields <n x <ty>></i>
3454 The '<tt>insertvalue</tt>' instruction inserts a value
3455 into a struct field or array element in an aggregate.
3462 The first operand of an '<tt>insertvalue</tt>' instruction is a
3463 value of <a href="#t_struct">struct</a> or <a href="#t_array">array</a> type.
3464 The second operand is a first-class value to insert.
3465 The following operands are constant indices
3466 indicating the position at which to insert the value in a similar manner as
3468 '<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.
3469 The value to insert must have the same type as the value identified
3476 The result is an aggregate of the same type as <tt>val</tt>. Its
3477 value is that of <tt>val</tt> except that the value at the position
3478 specified by the indices is that of <tt>elt</tt>.
3484 %result = insertvalue {i32, float} %agg, i32 1, 0 <i>; yields {i32, float}</i>
3489 <!-- ======================================================================= -->
3490 <div class="doc_subsection">
3491 <a name="memoryops">Memory Access and Addressing Operations</a>
3494 <div class="doc_text">
3496 <p>A key design point of an SSA-based representation is how it
3497 represents memory. In LLVM, no memory locations are in SSA form, which
3498 makes things very simple. This section describes how to read, write,
3499 allocate, and free memory in LLVM.</p>
3503 <!-- _______________________________________________________________________ -->
3504 <div class="doc_subsubsection">
3505 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
3508 <div class="doc_text">
3513 <result> = malloc <type>[, i32 <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
3518 <p>The '<tt>malloc</tt>' instruction allocates memory from the system
3519 heap and returns a pointer to it. The object is always allocated in the generic
3520 address space (address space zero).</p>
3524 <p>The '<tt>malloc</tt>' instruction allocates
3525 <tt>sizeof(<type>)*NumElements</tt>
3526 bytes of memory from the operating system and returns a pointer of the
3527 appropriate type to the program. If "NumElements" is specified, it is the
3528 number of elements allocated, otherwise "NumElements" is defaulted to be one.
3529 If a constant alignment is specified, the value result of the allocation is
3530 guaranteed to be aligned to at least that boundary. If not specified, or if
3531 zero, the target can choose to align the allocation on any convenient boundary
3532 compatible with the type.</p>
3534 <p>'<tt>type</tt>' must be a sized type.</p>
3538 <p>Memory is allocated using the system "<tt>malloc</tt>" function, and
3539 a pointer is returned. The result of a zero byte allocation is undefined. The
3540 result is null if there is insufficient memory available.</p>
3545 %array = malloc [4 x i8] <i>; yields {[%4 x i8]*}:array</i>
3547 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
3548 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
3549 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
3550 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
3551 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
3554 <p>Note that the code generator does not yet respect the
3555 alignment value.</p>
3559 <!-- _______________________________________________________________________ -->
3560 <div class="doc_subsubsection">
3561 <a name="i_free">'<tt>free</tt>' Instruction</a>
3564 <div class="doc_text">
3569 free <type> <value> <i>; yields {void}</i>
3574 <p>The '<tt>free</tt>' instruction returns memory back to the unused
3575 memory heap to be reallocated in the future.</p>
3579 <p>'<tt>value</tt>' shall be a pointer value that points to a value
3580 that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
3585 <p>Access to the memory pointed to by the pointer is no longer defined
3586 after this instruction executes. If the pointer is null, the operation
3592 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
3593 free [4 x i8]* %array
3597 <!-- _______________________________________________________________________ -->
3598 <div class="doc_subsubsection">
3599 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
3602 <div class="doc_text">
3607 <result> = alloca <type>[, i32 <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
3612 <p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
3613 currently executing function, to be automatically released when this function
3614 returns to its caller. The object is always allocated in the generic address
3615 space (address space zero).</p>
3619 <p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(<type>)*NumElements</tt>
3620 bytes of memory on the runtime stack, returning a pointer of the
3621 appropriate type to the program. If "NumElements" is specified, it is the
3622 number of elements allocated, otherwise "NumElements" is defaulted to be one.
3623 If a constant alignment is specified, the value result of the allocation is
3624 guaranteed to be aligned to at least that boundary. If not specified, or if
3625 zero, the target can choose to align the allocation on any convenient boundary
3626 compatible with the type.</p>
3628 <p>'<tt>type</tt>' may be any sized type.</p>
3632 <p>Memory is allocated; a pointer is returned. The operation is undefined if
3633 there is insufficient stack space for the allocation. '<tt>alloca</tt>'d
3634 memory is automatically released when the function returns. The '<tt>alloca</tt>'
3635 instruction is commonly used to represent automatic variables that must
3636 have an address available. When the function returns (either with the <tt><a
3637 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
3638 instructions), the memory is reclaimed. Allocating zero bytes
3639 is legal, but the result is undefined.</p>
3644 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
3645 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
3646 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
3647 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
3651 <!-- _______________________________________________________________________ -->
3652 <div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
3653 Instruction</a> </div>
3654 <div class="doc_text">
3656 <pre> <result> = load <ty>* <pointer>[, align <alignment>]<br> <result> = volatile load <ty>* <pointer>[, align <alignment>]<br></pre>
3658 <p>The '<tt>load</tt>' instruction is used to read from memory.</p>
3660 <p>The argument to the '<tt>load</tt>' instruction specifies the memory
3661 address from which to load. The pointer must point to a <a
3662 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
3663 marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
3664 the number or order of execution of this <tt>load</tt> with other
3665 volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
3668 The optional constant "align" argument specifies the alignment of the operation
3669 (that is, the alignment of the memory address). A value of 0 or an
3670 omitted "align" argument means that the operation has the preferential
3671 alignment for the target. It is the responsibility of the code emitter
3672 to ensure that the alignment information is correct. Overestimating
3673 the alignment results in an undefined behavior. Underestimating the
3674 alignment may produce less efficient code. An alignment of 1 is always
3678 <p>The location of memory pointed to is loaded. If the value being loaded
3679 is of scalar type then the number of bytes read does not exceed the minimum
3680 number of bytes needed to hold all bits of the type. For example, loading an
3681 <tt>i24</tt> reads at most three bytes. When loading a value of a type like
3682 <tt>i20</tt> with a size that is not an integral number of bytes, the result
3683 is undefined if the value was not originally written using a store of the
3686 <pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
3688 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
3689 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
3692 <!-- _______________________________________________________________________ -->
3693 <div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
3694 Instruction</a> </div>
3695 <div class="doc_text">
3697 <pre> store <ty> <value>, <ty>* <pointer>[, align <alignment>] <i>; yields {void}</i>
3698 volatile store <ty> <value>, <ty>* <pointer>[, align <alignment>] <i>; yields {void}</i>
3701 <p>The '<tt>store</tt>' instruction is used to write to memory.</p>
3703 <p>There are two arguments to the '<tt>store</tt>' instruction: a value
3704 to store and an address at which to store it. The type of the '<tt><pointer></tt>'
3705 operand must be a pointer to the <a href="#t_firstclass">first class</a> type
3706 of the '<tt><value></tt>'
3707 operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
3708 optimizer is not allowed to modify the number or order of execution of
3709 this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
3710 href="#i_store">store</a></tt> instructions.</p>
3712 The optional constant "align" argument specifies the alignment of the operation
3713 (that is, the alignment of the memory address). A value of 0 or an
3714 omitted "align" argument means that the operation has the preferential
3715 alignment for the target. It is the responsibility of the code emitter
3716 to ensure that the alignment information is correct. Overestimating
3717 the alignment results in an undefined behavior. Underestimating the
3718 alignment may produce less efficient code. An alignment of 1 is always
3722 <p>The contents of memory are updated to contain '<tt><value></tt>'
3723 at the location specified by the '<tt><pointer></tt>' operand.
3724 If '<tt><value></tt>' is of scalar type then the number of bytes
3725 written does not exceed the minimum number of bytes needed to hold all
3726 bits of the type. For example, storing an <tt>i24</tt> writes at most
3727 three bytes. When writing a value of a type like <tt>i20</tt> with a
3728 size that is not an integral number of bytes, it is unspecified what
3729 happens to the extra bits that do not belong to the type, but they will
3730 typically be overwritten.</p>
3732 <pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
3733 store i32 3, i32* %ptr <i>; yields {void}</i>
3734 %val = <a href="#i_load">load</a> i32* %ptr <i>; yields {i32}:val = i32 3</i>
3738 <!-- _______________________________________________________________________ -->
3739 <div class="doc_subsubsection">
3740 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
3743 <div class="doc_text">
3746 <result> = getelementptr <pty>* <ptrval>{, <ty> <idx>}*
3752 The '<tt>getelementptr</tt>' instruction is used to get the address of a
3753 subelement of an aggregate data structure. It performs address calculation only
3754 and does not access memory.</p>
3758 <p>The first argument is always a pointer, and forms the basis of the
3759 calculation. The remaining arguments are indices, that indicate which of the
3760 elements of the aggregate object are indexed. The interpretation of each index
3761 is dependent on the type being indexed into. The first index always indexes the
3762 pointer value given as the first argument, the second index indexes a value of
3763 the type pointed to (not necessarily the value directly pointed to, since the
3764 first index can be non-zero), etc. The first type indexed into must be a pointer
3765 value, subsequent types can be arrays, vectors and structs. Note that subsequent
3766 types being indexed into can never be pointers, since that would require loading
3767 the pointer before continuing calculation.</p>
3769 <p>The type of each index argument depends on the type it is indexing into.
3770 When indexing into a (packed) structure, only <tt>i32</tt> integer
3771 <b>constants</b> are allowed. When indexing into an array, pointer or vector,
3772 integers of any width are allowed (also non-constants).</p>
3774 <p>For example, let's consider a C code fragment and how it gets
3775 compiled to LLVM:</p>
3777 <div class="doc_code">
3790 int *foo(struct ST *s) {
3791 return &s[1].Z.B[5][13];
3796 <p>The LLVM code generated by the GCC frontend is:</p>
3798 <div class="doc_code">
3800 %RT = <a href="#namedtypes">type</a> { i8 , [10 x [20 x i32]], i8 }
3801 %ST = <a href="#namedtypes">type</a> { i32, double, %RT }
3803 define i32* %foo(%ST* %s) {
3805 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
3813 <p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
3814 type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
3815 }</tt>' type, a structure. The second index indexes into the third element of
3816 the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
3817 i8 }</tt>' type, another structure. The third index indexes into the second
3818 element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
3819 array. The two dimensions of the array are subscripted into, yielding an
3820 '<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
3821 to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
3823 <p>Note that it is perfectly legal to index partially through a
3824 structure, returning a pointer to an inner element. Because of this,
3825 the LLVM code for the given testcase is equivalent to:</p>
3828 define i32* %foo(%ST* %s) {
3829 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
3830 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
3831 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
3832 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
3833 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
3838 <p>Note that it is undefined to access an array out of bounds: array
3839 and pointer indexes must always be within the defined bounds of the
3840 array type when accessed with an instruction that dereferences the
3841 pointer (e.g. a load or store instruction). The one exception for
3842 this rule is zero length arrays. These arrays are defined to be
3843 accessible as variable length arrays, which requires access beyond the
3844 zero'th element.</p>
3846 <p>The getelementptr instruction is often confusing. For some more insight
3847 into how it works, see <a href="GetElementPtr.html">the getelementptr
3853 <i>; yields [12 x i8]*:aptr</i>
3854 %aptr = getelementptr {i32, [12 x i8]}* %saptr, i64 0, i32 1
3855 <i>; yields i8*:vptr</i>
3856 %vptr = getelementptr {i32, <2 x i8>}* %svptr, i64 0, i32 1, i32 1
3857 <i>; yields i8*:eptr</i>
3858 %eptr = getelementptr [12 x i8]* %aptr, i64 0, i32 1
3859 <i>; yields i32*:iptr</i>
3860 %iptr = getelementptr [10 x i32]* @arr, i16 0, i16 0
3864 <!-- ======================================================================= -->
3865 <div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
3867 <div class="doc_text">
3868 <p>The instructions in this category are the conversion instructions (casting)
3869 which all take a single operand and a type. They perform various bit conversions
3873 <!-- _______________________________________________________________________ -->
3874 <div class="doc_subsubsection">
3875 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
3877 <div class="doc_text">
3881 <result> = trunc <ty> <value> to <ty2> <i>; yields ty2</i>
3886 The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
3891 The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
3892 be an <a href="#t_integer">integer</a> type, and a type that specifies the size
3893 and type of the result, which must be an <a href="#t_integer">integer</a>
3894 type. The bit size of <tt>value</tt> must be larger than the bit size of
3895 <tt>ty2</tt>. Equal sized types are not allowed.</p>
3899 The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
3900 and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
3901 larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
3902 It will always truncate bits.</p>
3906 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
3907 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
3908 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
3912 <!-- _______________________________________________________________________ -->
3913 <div class="doc_subsubsection">
3914 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
3916 <div class="doc_text">
3920 <result> = zext <ty> <value> to <ty2> <i>; yields ty2</i>
3924 <p>The '<tt>zext</tt>' instruction zero extends its operand to type
3929 <p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
3930 <a href="#t_integer">integer</a> type, and a type to cast it to, which must
3931 also be of <a href="#t_integer">integer</a> type. The bit size of the
3932 <tt>value</tt> must be smaller than the bit size of the destination type,
3936 <p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
3937 bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>
3939 <p>When zero extending from i1, the result will always be either 0 or 1.</p>
3943 %X = zext i32 257 to i64 <i>; yields i64:257</i>
3944 %Y = zext i1 true to i32 <i>; yields i32:1</i>
3948 <!-- _______________________________________________________________________ -->
3949 <div class="doc_subsubsection">
3950 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
3952 <div class="doc_text">
3956 <result> = sext <ty> <value> to <ty2> <i>; yields ty2</i>
3960 <p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
3964 The '<tt>sext</tt>' instruction takes a value to cast, which must be of
3965 <a href="#t_integer">integer</a> type, and a type to cast it to, which must
3966 also be of <a href="#t_integer">integer</a> type. The bit size of the
3967 <tt>value</tt> must be smaller than the bit size of the destination type,
3972 The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
3973 bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
3974 the type <tt>ty2</tt>.</p>
3976 <p>When sign extending from i1, the extension always results in -1 or 0.</p>
3980 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
3981 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
3985 <!-- _______________________________________________________________________ -->
3986 <div class="doc_subsubsection">
3987 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
3990 <div class="doc_text">
3995 <result> = fptrunc <ty> <value> to <ty2> <i>; yields ty2</i>
3999 <p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
4004 <p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
4005 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
4006 cast it to. The size of <tt>value</tt> must be larger than the size of
4007 <tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
4008 <i>no-op cast</i>.</p>
4011 <p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
4012 <a href="#t_floating">floating point</a> type to a smaller
4013 <a href="#t_floating">floating point</a> type. If the value cannot fit within
4014 the destination type, <tt>ty2</tt>, then the results are undefined.</p>
4018 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
4019 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
4023 <!-- _______________________________________________________________________ -->
4024 <div class="doc_subsubsection">
4025 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
4027 <div class="doc_text">
4031 <result> = fpext <ty> <value> to <ty2> <i>; yields ty2</i>
4035 <p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
4036 floating point value.</p>
4039 <p>The '<tt>fpext</tt>' instruction takes a
4040 <a href="#t_floating">floating point</a> <tt>value</tt> to cast,
4041 and a <a href="#t_floating">floating point</a> type to cast it to. The source
4042 type must be smaller than the destination type.</p>
4045 <p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
4046 <a href="#t_floating">floating point</a> type to a larger
4047 <a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
4048 used to make a <i>no-op cast</i> because it always changes bits. Use
4049 <tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
4053 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
4054 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
4058 <!-- _______________________________________________________________________ -->
4059 <div class="doc_subsubsection">
4060 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
4062 <div class="doc_text">
4066 <result> = fptoui <ty> <value> to <ty2> <i>; yields ty2</i>
4070 <p>The '<tt>fptoui</tt>' converts a floating point <tt>value</tt> to its
4071 unsigned integer equivalent of type <tt>ty2</tt>.
4075 <p>The '<tt>fptoui</tt>' instruction takes a value to cast, which must be a
4076 scalar or vector <a href="#t_floating">floating point</a> value, and a type
4077 to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
4078 type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
4079 vector integer type with the same number of elements as <tt>ty</tt></p>
4082 <p> The '<tt>fptoui</tt>' instruction converts its
4083 <a href="#t_floating">floating point</a> operand into the nearest (rounding
4084 towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
4085 the results are undefined.</p>
4089 %X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
4090 %Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
4091 %X = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
4095 <!-- _______________________________________________________________________ -->
4096 <div class="doc_subsubsection">
4097 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
4099 <div class="doc_text">
4103 <result> = fptosi <ty> <value> to <ty2> <i>; yields ty2</i>
4107 <p>The '<tt>fptosi</tt>' instruction converts
4108 <a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
4112 <p> The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a
4113 scalar or vector <a href="#t_floating">floating point</a> value, and a type
4114 to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
4115 type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
4116 vector integer type with the same number of elements as <tt>ty</tt></p>
4119 <p>The '<tt>fptosi</tt>' instruction converts its
4120 <a href="#t_floating">floating point</a> operand into the nearest (rounding
4121 towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
4122 the results are undefined.</p>
4126 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
4127 %Y = fptosi float 1.0E-247 to i1 <i>; yields undefined:1</i>
4128 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
4132 <!-- _______________________________________________________________________ -->
4133 <div class="doc_subsubsection">
4134 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
4136 <div class="doc_text">
4140 <result> = uitofp <ty> <value> to <ty2> <i>; yields ty2</i>
4144 <p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
4145 integer and converts that value to the <tt>ty2</tt> type.</p>
4148 <p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be a
4149 scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
4150 to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
4151 type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
4152 floating point type with the same number of elements as <tt>ty</tt></p>
4155 <p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
4156 integer quantity and converts it to the corresponding floating point value. If
4157 the value cannot fit in the floating point value, the results are undefined.</p>
4161 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
4162 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
4166 <!-- _______________________________________________________________________ -->
4167 <div class="doc_subsubsection">
4168 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
4170 <div class="doc_text">
4174 <result> = sitofp <ty> <value> to <ty2> <i>; yields ty2</i>
4178 <p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
4179 integer and converts that value to the <tt>ty2</tt> type.</p>
4182 <p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be a
4183 scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
4184 to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
4185 type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
4186 floating point type with the same number of elements as <tt>ty</tt></p>
4189 <p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
4190 integer quantity and converts it to the corresponding floating point value. If
4191 the value cannot fit in the floating point value, the results are undefined.</p>
4195 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
4196 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
4200 <!-- _______________________________________________________________________ -->
4201 <div class="doc_subsubsection">
4202 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
4204 <div class="doc_text">
4208 <result> = ptrtoint <ty> <value> to <ty2> <i>; yields ty2</i>
4212 <p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
4213 the integer type <tt>ty2</tt>.</p>
4216 <p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
4217 must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
4218 <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.</p>
4221 <p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
4222 <tt>ty2</tt> by interpreting the pointer value as an integer and either
4223 truncating or zero extending that value to the size of the integer type. If
4224 <tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
4225 <tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
4226 are the same size, then nothing is done (<i>no-op cast</i>) other than a type
4231 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit architecture</i>
4232 %Y = ptrtoint i32* %x to i64 <i>; yields zero extension on 32-bit architecture</i>
4236 <!-- _______________________________________________________________________ -->
4237 <div class="doc_subsubsection">
4238 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
4240 <div class="doc_text">
4244 <result> = inttoptr <ty> <value> to <ty2> <i>; yields ty2</i>
4248 <p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
4249 a pointer type, <tt>ty2</tt>.</p>
4252 <p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
4253 value to cast, and a type to cast it to, which must be a
4254 <a href="#t_pointer">pointer</a> type.</p>
4257 <p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
4258 <tt>ty2</tt> by applying either a zero extension or a truncation depending on
4259 the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
4260 size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
4261 the size of a pointer then a zero extension is done. If they are the same size,
4262 nothing is done (<i>no-op cast</i>).</p>
4266 %X = inttoptr i32 255 to i32* <i>; yields zero extension on 64-bit architecture</i>
4267 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
4268 %Y = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
4272 <!-- _______________________________________________________________________ -->
4273 <div class="doc_subsubsection">
4274 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
4276 <div class="doc_text">
4280 <result> = bitcast <ty> <value> to <ty2> <i>; yields ty2</i>
4285 <p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
4286 <tt>ty2</tt> without changing any bits.</p>
4290 <p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
4291 a non-aggregate first class value, and a type to cast it to, which must also be
4292 a non-aggregate <a href="#t_firstclass">first class</a> type. The bit sizes of
4294 and the destination type, <tt>ty2</tt>, must be identical. If the source
4295 type is a pointer, the destination type must also be a pointer. This
4296 instruction supports bitwise conversion of vectors to integers and to vectors
4297 of other types (as long as they have the same size).</p>
4300 <p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
4301 <tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
4302 this conversion. The conversion is done as if the <tt>value</tt> had been
4303 stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
4304 converted to other pointer types with this instruction. To convert pointers to
4305 other types, use the <a href="#i_inttoptr">inttoptr</a> or
4306 <a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
4310 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
4311 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
4312 %Z = bitcast <2 x int> %V to i64; <i>; yields i64: %V</i>
4316 <!-- ======================================================================= -->
4317 <div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
4318 <div class="doc_text">
4319 <p>The instructions in this category are the "miscellaneous"
4320 instructions, which defy better classification.</p>
4323 <!-- _______________________________________________________________________ -->
4324 <div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
4326 <div class="doc_text">
4328 <pre> <result> = icmp <cond> <ty> <op1>, <op2> <i>; yields {i1} or {<N x i1>}:result</i>
4331 <p>The '<tt>icmp</tt>' instruction returns a boolean value or
4332 a vector of boolean values based on comparison
4333 of its two integer, integer vector, or pointer operands.</p>
4335 <p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
4336 the condition code indicating the kind of comparison to perform. It is not
4337 a value, just a keyword. The possible condition code are:
4340 <li><tt>eq</tt>: equal</li>
4341 <li><tt>ne</tt>: not equal </li>
4342 <li><tt>ugt</tt>: unsigned greater than</li>
4343 <li><tt>uge</tt>: unsigned greater or equal</li>
4344 <li><tt>ult</tt>: unsigned less than</li>
4345 <li><tt>ule</tt>: unsigned less or equal</li>
4346 <li><tt>sgt</tt>: signed greater than</li>
4347 <li><tt>sge</tt>: signed greater or equal</li>
4348 <li><tt>slt</tt>: signed less than</li>
4349 <li><tt>sle</tt>: signed less or equal</li>
4351 <p>The remaining two arguments must be <a href="#t_integer">integer</a> or
4352 <a href="#t_pointer">pointer</a>
4353 or integer <a href="#t_vector">vector</a> typed.
4354 They must also be identical types.</p>
4356 <p>The '<tt>icmp</tt>' compares <tt>op1</tt> and <tt>op2</tt> according to
4357 the condition code given as <tt>cond</tt>. The comparison performed always
4358 yields either an <a href="#t_primitive"><tt>i1</tt></a> or vector of <tt>i1</tt> result, as follows:
4361 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
4362 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
4364 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
4365 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.</li>
4366 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
4367 <tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
4368 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
4369 <tt>true</tt> if <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
4370 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
4371 <tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
4372 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
4373 <tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
4374 <li><tt>sgt</tt>: interprets the operands as signed values and yields
4375 <tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
4376 <li><tt>sge</tt>: interprets the operands as signed values and yields
4377 <tt>true</tt> if <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
4378 <li><tt>slt</tt>: interprets the operands as signed values and yields
4379 <tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
4380 <li><tt>sle</tt>: interprets the operands as signed values and yields
4381 <tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
4383 <p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
4384 values are compared as if they were integers.</p>
4385 <p>If the operands are integer vectors, then they are compared
4386 element by element. The result is an <tt>i1</tt> vector with
4387 the same number of elements as the values being compared.
4388 Otherwise, the result is an <tt>i1</tt>.
4392 <pre> <result> = icmp eq i32 4, 5 <i>; yields: result=false</i>
4393 <result> = icmp ne float* %X, %X <i>; yields: result=false</i>
4394 <result> = icmp ult i16 4, 5 <i>; yields: result=true</i>
4395 <result> = icmp sgt i16 4, 5 <i>; yields: result=false</i>
4396 <result> = icmp ule i16 -4, 5 <i>; yields: result=false</i>
4397 <result> = icmp sge i16 4, 5 <i>; yields: result=false</i>
4400 <p>Note that the code generator does not yet support vector types with
4401 the <tt>icmp</tt> instruction.</p>
4405 <!-- _______________________________________________________________________ -->
4406 <div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
4408 <div class="doc_text">
4410 <pre> <result> = fcmp <cond> <ty> <op1>, <op2> <i>; yields {i1} or {<N x i1>}:result</i>
4413 <p>The '<tt>fcmp</tt>' instruction returns a boolean value
4414 or vector of boolean values based on comparison
4415 of its operands.</p>
4417 If the operands are floating point scalars, then the result
4418 type is a boolean (<a href="#t_primitive"><tt>i1</tt></a>).
4420 <p>If the operands are floating point vectors, then the result type
4421 is a vector of boolean with the same number of elements as the
4422 operands being compared.</p>
4424 <p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
4425 the condition code indicating the kind of comparison to perform. It is not
4426 a value, just a keyword. The possible condition code are:</p>
4428 <li><tt>false</tt>: no comparison, always returns false</li>
4429 <li><tt>oeq</tt>: ordered and equal</li>
4430 <li><tt>ogt</tt>: ordered and greater than </li>
4431 <li><tt>oge</tt>: ordered and greater than or equal</li>
4432 <li><tt>olt</tt>: ordered and less than </li>
4433 <li><tt>ole</tt>: ordered and less than or equal</li>
4434 <li><tt>one</tt>: ordered and not equal</li>
4435 <li><tt>ord</tt>: ordered (no nans)</li>
4436 <li><tt>ueq</tt>: unordered or equal</li>
4437 <li><tt>ugt</tt>: unordered or greater than </li>
4438 <li><tt>uge</tt>: unordered or greater than or equal</li>
4439 <li><tt>ult</tt>: unordered or less than </li>
4440 <li><tt>ule</tt>: unordered or less than or equal</li>
4441 <li><tt>une</tt>: unordered or not equal</li>
4442 <li><tt>uno</tt>: unordered (either nans)</li>
4443 <li><tt>true</tt>: no comparison, always returns true</li>
4445 <p><i>Ordered</i> means that neither operand is a QNAN while
4446 <i>unordered</i> means that either operand may be a QNAN.</p>
4447 <p>Each of <tt>val1</tt> and <tt>val2</tt> arguments must be
4448 either a <a href="#t_floating">floating point</a> type
4449 or a <a href="#t_vector">vector</a> of floating point type.
4450 They must have identical types.</p>
4452 <p>The '<tt>fcmp</tt>' instruction compares <tt>op1</tt> and <tt>op2</tt>
4453 according to the condition code given as <tt>cond</tt>.
4454 If the operands are vectors, then the vectors are compared
4456 Each comparison performed
4457 always yields an <a href="#t_primitive">i1</a> result, as follows:</p>
4459 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
4460 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
4461 <tt>op1</tt> is equal to <tt>op2</tt>.</li>
4462 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
4463 <tt>op1</tt> is greather than <tt>op2</tt>.</li>
4464 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
4465 <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
4466 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
4467 <tt>op1</tt> is less than <tt>op2</tt>.</li>
4468 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
4469 <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
4470 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
4471 <tt>op1</tt> is not equal to <tt>op2</tt>.</li>
4472 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
4473 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
4474 <tt>op1</tt> is equal to <tt>op2</tt>.</li>
4475 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
4476 <tt>op1</tt> is greater than <tt>op2</tt>.</li>
4477 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
4478 <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
4479 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
4480 <tt>op1</tt> is less than <tt>op2</tt>.</li>
4481 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
4482 <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
4483 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
4484 <tt>op1</tt> is not equal to <tt>op2</tt>.</li>
4485 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
4486 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
4490 <pre> <result> = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
4491 <result> = fcmp one float 4.0, 5.0 <i>; yields: result=true</i>
4492 <result> = fcmp olt float 4.0, 5.0 <i>; yields: result=true</i>
4493 <result> = fcmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
4496 <p>Note that the code generator does not yet support vector types with
4497 the <tt>fcmp</tt> instruction.</p>
4501 <!-- _______________________________________________________________________ -->
4502 <div class="doc_subsubsection">
4503 <a name="i_phi">'<tt>phi</tt>' Instruction</a>
4506 <div class="doc_text">
4510 <pre> <result> = phi <ty> [ <val0>, <label0>], ...<br></pre>
4512 <p>The '<tt>phi</tt>' instruction is used to implement the φ node in
4513 the SSA graph representing the function.</p>
4516 <p>The type of the incoming values is specified with the first type
4517 field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
4518 as arguments, with one pair for each predecessor basic block of the
4519 current block. Only values of <a href="#t_firstclass">first class</a>
4520 type may be used as the value arguments to the PHI node. Only labels
4521 may be used as the label arguments.</p>
4523 <p>There must be no non-phi instructions between the start of a basic
4524 block and the PHI instructions: i.e. PHI instructions must be first in
4527 <p>For the purposes of the SSA form, the use of each incoming value is
4528 deemed to occur on the edge from the corresponding predecessor block
4529 to the current block (but after any definition of an '<tt>invoke</tt>'
4530 instruction's return value on the same edge).</p>
4534 <p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
4535 specified by the pair corresponding to the predecessor basic block that executed
4536 just prior to the current block.</p>
4540 Loop: ; Infinite loop that counts from 0 on up...
4541 %indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
4542 %nextindvar = add i32 %indvar, 1
4547 <!-- _______________________________________________________________________ -->
4548 <div class="doc_subsubsection">
4549 <a name="i_select">'<tt>select</tt>' Instruction</a>
4552 <div class="doc_text">
4557 <result> = select <i>selty</i> <cond>, <ty> <val1>, <ty> <val2> <i>; yields ty</i>
4559 <i>selty</i> is either i1 or {<N x i1>}
4565 The '<tt>select</tt>' instruction is used to choose one value based on a
4566 condition, without branching.
4573 The '<tt>select</tt>' instruction requires an 'i1' value or
4574 a vector of 'i1' values indicating the
4575 condition, and two values of the same <a href="#t_firstclass">first class</a>
4576 type. If the val1/val2 are vectors and
4577 the condition is a scalar, then entire vectors are selected, not
4578 individual elements.
4584 If the condition is an i1 and it evaluates to 1, the instruction returns the first
4585 value argument; otherwise, it returns the second value argument.
4588 If the condition is a vector of i1, then the value arguments must
4589 be vectors of the same size, and the selection is done element
4596 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
4599 <p>Note that the code generator does not yet support conditions
4600 with vector type.</p>
4605 <!-- _______________________________________________________________________ -->
4606 <div class="doc_subsubsection">
4607 <a name="i_call">'<tt>call</tt>' Instruction</a>
4610 <div class="doc_text">
4614 <result> = [tail] call [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>] <ty> [<fnty>*] <fnptrval>(<function args>) [<a href="#fnattrs">fn attrs</a>]
4619 <p>The '<tt>call</tt>' instruction represents a simple function call.</p>
4623 <p>This instruction requires several arguments:</p>
4627 <p>The optional "tail" marker indicates whether the callee function accesses
4628 any allocas or varargs in the caller. If the "tail" marker is present, the
4629 function call is eligible for tail call optimization. Note that calls may
4630 be marked "tail" even if they do not occur before a <a
4631 href="#i_ret"><tt>ret</tt></a> instruction.</p>
4634 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
4635 convention</a> the call should use. If none is specified, the call defaults
4636 to using C calling conventions.</p>
4640 <p>The optional <a href="#paramattrs">Parameter Attributes</a> list for
4641 return values. Only '<tt>zeroext</tt>', '<tt>signext</tt>',
4642 and '<tt>inreg</tt>' attributes are valid here.</p>
4646 <p>'<tt>ty</tt>': the type of the call instruction itself which is also
4647 the type of the return value. Functions that return no value are marked
4648 <tt><a href="#t_void">void</a></tt>.</p>
4651 <p>'<tt>fnty</tt>': shall be the signature of the pointer to function
4652 value being invoked. The argument types must match the types implied by
4653 this signature. This type can be omitted if the function is not varargs
4654 and if the function type does not return a pointer to a function.</p>
4657 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
4658 be invoked. In most cases, this is a direct function invocation, but
4659 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
4660 to function value.</p>
4663 <p>'<tt>function args</tt>': argument list whose types match the
4664 function signature argument types. All arguments must be of
4665 <a href="#t_firstclass">first class</a> type. If the function signature
4666 indicates the function accepts a variable number of arguments, the extra
4667 arguments can be specified.</p>
4670 <p>The optional <a href="#fnattrs">function attributes</a> list. Only
4671 '<tt>noreturn</tt>', '<tt>nounwind</tt>', '<tt>readonly</tt>' and
4672 '<tt>readnone</tt>' attributes are valid here.</p>
4678 <p>The '<tt>call</tt>' instruction is used to cause control flow to
4679 transfer to a specified function, with its incoming arguments bound to
4680 the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
4681 instruction in the called function, control flow continues with the
4682 instruction after the function call, and the return value of the
4683 function is bound to the result argument.</p>
4688 %retval = call i32 @test(i32 %argc)
4689 call i32 (i8 *, ...)* @printf(i8 * %msg, i32 12, i8 42) <i>; yields i32</i>
4690 %X = tail call i32 @foo() <i>; yields i32</i>
4691 %Y = tail call <a href="#callingconv">fastcc</a> i32 @foo() <i>; yields i32</i>
4692 call void %foo(i8 97 signext)
4694 %struct.A = type { i32, i8 }
4695 %r = call %struct.A @foo() <i>; yields { 32, i8 }</i>
4696 %gr = extractvalue %struct.A %r, 0 <i>; yields i32</i>
4697 %gr1 = extractvalue %struct.A %r, 1 <i>; yields i8</i>
4698 %Z = call void @foo() noreturn <i>; indicates that %foo never returns normally</i>
4699 %ZZ = call zeroext i32 @bar() <i>; Return value is %zero extended</i>
4704 <!-- _______________________________________________________________________ -->
4705 <div class="doc_subsubsection">
4706 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
4709 <div class="doc_text">
4714 <resultval> = va_arg <va_list*> <arglist>, <argty>
4719 <p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
4720 the "variable argument" area of a function call. It is used to implement the
4721 <tt>va_arg</tt> macro in C.</p>
4725 <p>This instruction takes a <tt>va_list*</tt> value and the type of
4726 the argument. It returns a value of the specified argument type and
4727 increments the <tt>va_list</tt> to point to the next argument. The
4728 actual type of <tt>va_list</tt> is target specific.</p>
4732 <p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
4733 type from the specified <tt>va_list</tt> and causes the
4734 <tt>va_list</tt> to point to the next argument. For more information,
4735 see the variable argument handling <a href="#int_varargs">Intrinsic
4738 <p>It is legal for this instruction to be called in a function which does not
4739 take a variable number of arguments, for example, the <tt>vfprintf</tt>
4742 <p><tt>va_arg</tt> is an LLVM instruction instead of an <a
4743 href="#intrinsics">intrinsic function</a> because it takes a type as an
4748 <p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
4750 <p>Note that the code generator does not yet fully support va_arg
4751 on many targets. Also, it does not currently support va_arg with
4752 aggregate types on any target.</p>
4756 <!-- *********************************************************************** -->
4757 <div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
4758 <!-- *********************************************************************** -->
4760 <div class="doc_text">
4762 <p>LLVM supports the notion of an "intrinsic function". These functions have
4763 well known names and semantics and are required to follow certain restrictions.
4764 Overall, these intrinsics represent an extension mechanism for the LLVM
4765 language that does not require changing all of the transformations in LLVM when
4766 adding to the language (or the bitcode reader/writer, the parser, etc...).</p>
4768 <p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
4769 prefix is reserved in LLVM for intrinsic names; thus, function names may not
4770 begin with this prefix. Intrinsic functions must always be external functions:
4771 you cannot define the body of intrinsic functions. Intrinsic functions may
4772 only be used in call or invoke instructions: it is illegal to take the address
4773 of an intrinsic function. Additionally, because intrinsic functions are part
4774 of the LLVM language, it is required if any are added that they be documented
4777 <p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents
4778 a family of functions that perform the same operation but on different data
4779 types. Because LLVM can represent over 8 million different integer types,
4780 overloading is used commonly to allow an intrinsic function to operate on any
4781 integer type. One or more of the argument types or the result type can be
4782 overloaded to accept any integer type. Argument types may also be defined as
4783 exactly matching a previous argument's type or the result type. This allows an
4784 intrinsic function which accepts multiple arguments, but needs all of them to
4785 be of the same type, to only be overloaded with respect to a single argument or
4788 <p>Overloaded intrinsics will have the names of its overloaded argument types
4789 encoded into its function name, each preceded by a period. Only those types
4790 which are overloaded result in a name suffix. Arguments whose type is matched
4791 against another type do not. For example, the <tt>llvm.ctpop</tt> function can
4792 take an integer of any width and returns an integer of exactly the same integer
4793 width. This leads to a family of functions such as
4794 <tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29 %val)</tt>.
4795 Only one type, the return type, is overloaded, and only one type suffix is
4796 required. Because the argument's type is matched against the return type, it
4797 does not require its own name suffix.</p>
4799 <p>To learn how to add an intrinsic function, please see the
4800 <a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
4805 <!-- ======================================================================= -->
4806 <div class="doc_subsection">
4807 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
4810 <div class="doc_text">
4812 <p>Variable argument support is defined in LLVM with the <a
4813 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
4814 intrinsic functions. These functions are related to the similarly
4815 named macros defined in the <tt><stdarg.h></tt> header file.</p>
4817 <p>All of these functions operate on arguments that use a
4818 target-specific value type "<tt>va_list</tt>". The LLVM assembly
4819 language reference manual does not define what this type is, so all
4820 transformations should be prepared to handle these functions regardless of
4823 <p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
4824 instruction and the variable argument handling intrinsic functions are
4827 <div class="doc_code">
4829 define i32 @test(i32 %X, ...) {
4830 ; Initialize variable argument processing
4832 %ap2 = bitcast i8** %ap to i8*
4833 call void @llvm.va_start(i8* %ap2)
4835 ; Read a single integer argument
4836 %tmp = va_arg i8** %ap, i32
4838 ; Demonstrate usage of llvm.va_copy and llvm.va_end
4840 %aq2 = bitcast i8** %aq to i8*
4841 call void @llvm.va_copy(i8* %aq2, i8* %ap2)
4842 call void @llvm.va_end(i8* %aq2)
4844 ; Stop processing of arguments.
4845 call void @llvm.va_end(i8* %ap2)
4849 declare void @llvm.va_start(i8*)
4850 declare void @llvm.va_copy(i8*, i8*)
4851 declare void @llvm.va_end(i8*)
4857 <!-- _______________________________________________________________________ -->
4858 <div class="doc_subsubsection">
4859 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
4863 <div class="doc_text">
4865 <pre> declare void %llvm.va_start(i8* <arglist>)<br></pre>
4867 <p>The '<tt>llvm.va_start</tt>' intrinsic initializes
4868 <tt>*<arglist></tt> for subsequent use by <tt><a
4869 href="#i_va_arg">va_arg</a></tt>.</p>
4873 <p>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
4877 <p>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
4878 macro available in C. In a target-dependent way, it initializes the
4879 <tt>va_list</tt> element to which the argument points, so that the next call to
4880 <tt>va_arg</tt> will produce the first variable argument passed to the function.
4881 Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
4882 last argument of the function as the compiler can figure that out.</p>
4886 <!-- _______________________________________________________________________ -->
4887 <div class="doc_subsubsection">
4888 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
4891 <div class="doc_text">
4893 <pre> declare void @llvm.va_end(i8* <arglist>)<br></pre>
4896 <p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*<arglist></tt>,
4897 which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
4898 or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
4902 <p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>
4906 <p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
4907 macro available in C. In a target-dependent way, it destroys the
4908 <tt>va_list</tt> element to which the argument points. Calls to <a
4909 href="#int_va_start"><tt>llvm.va_start</tt></a> and <a href="#int_va_copy">
4910 <tt>llvm.va_copy</tt></a> must be matched exactly with calls to
4911 <tt>llvm.va_end</tt>.</p>
4915 <!-- _______________________________________________________________________ -->
4916 <div class="doc_subsubsection">
4917 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
4920 <div class="doc_text">
4925 declare void @llvm.va_copy(i8* <destarglist>, i8* <srcarglist>)
4930 <p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
4931 from the source argument list to the destination argument list.</p>
4935 <p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
4936 The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
4941 <p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
4942 macro available in C. In a target-dependent way, it copies the source
4943 <tt>va_list</tt> element into the destination <tt>va_list</tt> element. This
4944 intrinsic is necessary because the <tt><a href="#int_va_start">
4945 llvm.va_start</a></tt> intrinsic may be arbitrarily complex and require, for
4946 example, memory allocation.</p>
4950 <!-- ======================================================================= -->
4951 <div class="doc_subsection">
4952 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
4955 <div class="doc_text">
4958 LLVM support for <a href="GarbageCollection.html">Accurate Garbage
4959 Collection</a> (GC) requires the implementation and generation of these
4961 These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
4962 stack</a>, as well as garbage collector implementations that require <a
4963 href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
4964 Front-ends for type-safe garbage collected languages should generate these
4965 intrinsics to make use of the LLVM garbage collectors. For more details, see <a
4966 href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
4969 <p>The garbage collection intrinsics only operate on objects in the generic
4970 address space (address space zero).</p>
4974 <!-- _______________________________________________________________________ -->
4975 <div class="doc_subsubsection">
4976 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
4979 <div class="doc_text">
4984 declare void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
4989 <p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
4990 the code generator, and allows some metadata to be associated with it.</p>
4994 <p>The first argument specifies the address of a stack object that contains the
4995 root pointer. The second pointer (which must be either a constant or a global
4996 value address) contains the meta-data to be associated with the root.</p>
5000 <p>At runtime, a call to this intrinsic stores a null pointer into the "ptrloc"
5001 location. At compile-time, the code generator generates information to allow
5002 the runtime to find the pointer at GC safe points. The '<tt>llvm.gcroot</tt>'
5003 intrinsic may only be used in a function which <a href="#gc">specifies a GC
5009 <!-- _______________________________________________________________________ -->
5010 <div class="doc_subsubsection">
5011 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
5014 <div class="doc_text">
5019 declare i8* @llvm.gcread(i8* %ObjPtr, i8** %Ptr)
5024 <p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
5025 locations, allowing garbage collector implementations that require read
5030 <p>The second argument is the address to read from, which should be an address
5031 allocated from the garbage collector. The first object is a pointer to the
5032 start of the referenced object, if needed by the language runtime (otherwise
5037 <p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
5038 instruction, but may be replaced with substantially more complex code by the
5039 garbage collector runtime, as needed. The '<tt>llvm.gcread</tt>' intrinsic
5040 may only be used in a function which <a href="#gc">specifies a GC
5046 <!-- _______________________________________________________________________ -->
5047 <div class="doc_subsubsection">
5048 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
5051 <div class="doc_text">
5056 declare void @llvm.gcwrite(i8* %P1, i8* %Obj, i8** %P2)
5061 <p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
5062 locations, allowing garbage collector implementations that require write
5063 barriers (such as generational or reference counting collectors).</p>
5067 <p>The first argument is the reference to store, the second is the start of the
5068 object to store it to, and the third is the address of the field of Obj to
5069 store to. If the runtime does not require a pointer to the object, Obj may be
5074 <p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
5075 instruction, but may be replaced with substantially more complex code by the
5076 garbage collector runtime, as needed. The '<tt>llvm.gcwrite</tt>' intrinsic
5077 may only be used in a function which <a href="#gc">specifies a GC
5084 <!-- ======================================================================= -->
5085 <div class="doc_subsection">
5086 <a name="int_codegen">Code Generator Intrinsics</a>
5089 <div class="doc_text">
5091 These intrinsics are provided by LLVM to expose special features that may only
5092 be implemented with code generator support.
5097 <!-- _______________________________________________________________________ -->
5098 <div class="doc_subsubsection">
5099 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
5102 <div class="doc_text">
5106 declare i8 *@llvm.returnaddress(i32 <level>)
5112 The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
5113 target-specific value indicating the return address of the current function
5114 or one of its callers.
5120 The argument to this intrinsic indicates which function to return the address
5121 for. Zero indicates the calling function, one indicates its caller, etc. The
5122 argument is <b>required</b> to be a constant integer value.
5128 The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
5129 the return address of the specified call frame, or zero if it cannot be
5130 identified. The value returned by this intrinsic is likely to be incorrect or 0
5131 for arguments other than zero, so it should only be used for debugging purposes.
5135 Note that calling this intrinsic does not prevent function inlining or other
5136 aggressive transformations, so the value returned may not be that of the obvious
5137 source-language caller.
5142 <!-- _______________________________________________________________________ -->
5143 <div class="doc_subsubsection">
5144 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
5147 <div class="doc_text">
5151 declare i8 *@llvm.frameaddress(i32 <level>)
5157 The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
5158 target-specific frame pointer value for the specified stack frame.
5164 The argument to this intrinsic indicates which function to return the frame
5165 pointer for. Zero indicates the calling function, one indicates its caller,
5166 etc. The argument is <b>required</b> to be a constant integer value.
5172 The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
5173 the frame address of the specified call frame, or zero if it cannot be
5174 identified. The value returned by this intrinsic is likely to be incorrect or 0
5175 for arguments other than zero, so it should only be used for debugging purposes.
5179 Note that calling this intrinsic does not prevent function inlining or other
5180 aggressive transformations, so the value returned may not be that of the obvious
5181 source-language caller.
5185 <!-- _______________________________________________________________________ -->
5186 <div class="doc_subsubsection">
5187 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
5190 <div class="doc_text">
5194 declare i8 *@llvm.stacksave()
5200 The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
5201 the function stack, for use with <a href="#int_stackrestore">
5202 <tt>llvm.stackrestore</tt></a>. This is useful for implementing language
5203 features like scoped automatic variable sized arrays in C99.
5209 This intrinsic returns a opaque pointer value that can be passed to <a
5210 href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
5211 <tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
5212 <tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
5213 state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
5214 practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
5215 that were allocated after the <tt>llvm.stacksave</tt> was executed.
5220 <!-- _______________________________________________________________________ -->
5221 <div class="doc_subsubsection">
5222 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
5225 <div class="doc_text">
5229 declare void @llvm.stackrestore(i8 * %ptr)
5235 The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
5236 the function stack to the state it was in when the corresponding <a
5237 href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
5238 useful for implementing language features like scoped automatic variable sized
5245 See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
5251 <!-- _______________________________________________________________________ -->
5252 <div class="doc_subsubsection">
5253 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
5256 <div class="doc_text">
5260 declare void @llvm.prefetch(i8* <address>, i32 <rw>, i32 <locality>)
5267 The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
5268 a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
5270 effect on the behavior of the program but can change its performance
5277 <tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
5278 determining if the fetch should be for a read (0) or write (1), and
5279 <tt>locality</tt> is a temporal locality specifier ranging from (0) - no
5280 locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
5281 <tt>locality</tt> arguments must be constant integers.
5287 This intrinsic does not modify the behavior of the program. In particular,
5288 prefetches cannot trap and do not produce a value. On targets that support this
5289 intrinsic, the prefetch can provide hints to the processor cache for better
5295 <!-- _______________________________________________________________________ -->
5296 <div class="doc_subsubsection">
5297 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
5300 <div class="doc_text">
5304 declare void @llvm.pcmarker(i32 <id>)
5311 The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
5313 code to simulators and other tools. The method is target specific, but it is
5314 expected that the marker will use exported symbols to transmit the PC of the
5316 The marker makes no guarantees that it will remain with any specific instruction
5317 after optimizations. It is possible that the presence of a marker will inhibit
5318 optimizations. The intended use is to be inserted after optimizations to allow
5319 correlations of simulation runs.
5325 <tt>id</tt> is a numerical id identifying the marker.
5331 This intrinsic does not modify the behavior of the program. Backends that do not
5332 support this intrinisic may ignore it.
5337 <!-- _______________________________________________________________________ -->
5338 <div class="doc_subsubsection">
5339 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
5342 <div class="doc_text">
5346 declare i64 @llvm.readcyclecounter( )
5353 The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
5354 counter register (or similar low latency, high accuracy clocks) on those targets
5355 that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
5356 As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
5357 should only be used for small timings.
5363 When directly supported, reading the cycle counter should not modify any memory.
5364 Implementations are allowed to either return a application specific value or a
5365 system wide value. On backends without support, this is lowered to a constant 0.
5370 <!-- ======================================================================= -->
5371 <div class="doc_subsection">
5372 <a name="int_libc">Standard C Library Intrinsics</a>
5375 <div class="doc_text">
5377 LLVM provides intrinsics for a few important standard C library functions.
5378 These intrinsics allow source-language front-ends to pass information about the
5379 alignment of the pointer arguments to the code generator, providing opportunity
5380 for more efficient code generation.
5385 <!-- _______________________________________________________________________ -->
5386 <div class="doc_subsubsection">
5387 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
5390 <div class="doc_text">
5393 <p>This is an overloaded intrinsic. You can use llvm.memcpy on any integer bit
5394 width. Not all targets support all bit widths however.</p>
5396 declare void @llvm.memcpy.i8(i8 * <dest>, i8 * <src>,
5397 i8 <len>, i32 <align>)
5398 declare void @llvm.memcpy.i16(i8 * <dest>, i8 * <src>,
5399 i16 <len>, i32 <align>)
5400 declare void @llvm.memcpy.i32(i8 * <dest>, i8 * <src>,
5401 i32 <len>, i32 <align>)
5402 declare void @llvm.memcpy.i64(i8 * <dest>, i8 * <src>,
5403 i64 <len>, i32 <align>)
5409 The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
5410 location to the destination location.
5414 Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
5415 intrinsics do not return a value, and takes an extra alignment argument.
5421 The first argument is a pointer to the destination, the second is a pointer to
5422 the source. The third argument is an integer argument
5423 specifying the number of bytes to copy, and the fourth argument is the alignment
5424 of the source and destination locations.
5428 If the call to this intrinisic has an alignment value that is not 0 or 1, then
5429 the caller guarantees that both the source and destination pointers are aligned
5436 The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
5437 location to the destination location, which are not allowed to overlap. It
5438 copies "len" bytes of memory over. If the argument is known to be aligned to
5439 some boundary, this can be specified as the fourth argument, otherwise it should
5445 <!-- _______________________________________________________________________ -->
5446 <div class="doc_subsubsection">
5447 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
5450 <div class="doc_text">
5453 <p>This is an overloaded intrinsic. You can use llvm.memmove on any integer bit
5454 width. Not all targets support all bit widths however.</p>
5456 declare void @llvm.memmove.i8(i8 * <dest>, i8 * <src>,
5457 i8 <len>, i32 <align>)
5458 declare void @llvm.memmove.i16(i8 * <dest>, i8 * <src>,
5459 i16 <len>, i32 <align>)
5460 declare void @llvm.memmove.i32(i8 * <dest>, i8 * <src>,
5461 i32 <len>, i32 <align>)
5462 declare void @llvm.memmove.i64(i8 * <dest>, i8 * <src>,
5463 i64 <len>, i32 <align>)
5469 The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
5470 location to the destination location. It is similar to the
5471 '<tt>llvm.memcpy</tt>' intrinsic but allows the two memory locations to overlap.
5475 Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
5476 intrinsics do not return a value, and takes an extra alignment argument.
5482 The first argument is a pointer to the destination, the second is a pointer to
5483 the source. The third argument is an integer argument
5484 specifying the number of bytes to copy, and the fourth argument is the alignment
5485 of the source and destination locations.
5489 If the call to this intrinisic has an alignment value that is not 0 or 1, then
5490 the caller guarantees that the source and destination pointers are aligned to
5497 The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
5498 location to the destination location, which may overlap. It
5499 copies "len" bytes of memory over. If the argument is known to be aligned to
5500 some boundary, this can be specified as the fourth argument, otherwise it should
5506 <!-- _______________________________________________________________________ -->
5507 <div class="doc_subsubsection">
5508 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
5511 <div class="doc_text">
5514 <p>This is an overloaded intrinsic. You can use llvm.memset on any integer bit
5515 width. Not all targets support all bit widths however.</p>
5517 declare void @llvm.memset.i8(i8 * <dest>, i8 <val>,
5518 i8 <len>, i32 <align>)
5519 declare void @llvm.memset.i16(i8 * <dest>, i8 <val>,
5520 i16 <len>, i32 <align>)
5521 declare void @llvm.memset.i32(i8 * <dest>, i8 <val>,
5522 i32 <len>, i32 <align>)
5523 declare void @llvm.memset.i64(i8 * <dest>, i8 <val>,
5524 i64 <len>, i32 <align>)
5530 The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
5535 Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
5536 does not return a value, and takes an extra alignment argument.
5542 The first argument is a pointer to the destination to fill, the second is the
5543 byte value to fill it with, the third argument is an integer
5544 argument specifying the number of bytes to fill, and the fourth argument is the
5545 known alignment of destination location.
5549 If the call to this intrinisic has an alignment value that is not 0 or 1, then
5550 the caller guarantees that the destination pointer is aligned to that boundary.
5556 The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
5558 destination location. If the argument is known to be aligned to some boundary,
5559 this can be specified as the fourth argument, otherwise it should be set to 0 or
5565 <!-- _______________________________________________________________________ -->
5566 <div class="doc_subsubsection">
5567 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
5570 <div class="doc_text">
5573 <p>This is an overloaded intrinsic. You can use <tt>llvm.sqrt</tt> on any
5574 floating point or vector of floating point type. Not all targets support all
5577 declare float @llvm.sqrt.f32(float %Val)
5578 declare double @llvm.sqrt.f64(double %Val)
5579 declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
5580 declare fp128 @llvm.sqrt.f128(fp128 %Val)
5581 declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %Val)
5587 The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
5588 returning the same value as the libm '<tt>sqrt</tt>' functions would. Unlike
5589 <tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
5590 negative numbers other than -0.0 (which allows for better optimization, because
5591 there is no need to worry about errno being set). <tt>llvm.sqrt(-0.0)</tt> is
5592 defined to return -0.0 like IEEE sqrt.
5598 The argument and return value are floating point numbers of the same type.
5604 This function returns the sqrt of the specified operand if it is a nonnegative
5605 floating point number.
5609 <!-- _______________________________________________________________________ -->
5610 <div class="doc_subsubsection">
5611 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
5614 <div class="doc_text">
5617 <p>This is an overloaded intrinsic. You can use <tt>llvm.powi</tt> on any
5618 floating point or vector of floating point type. Not all targets support all
5621 declare float @llvm.powi.f32(float %Val, i32 %power)
5622 declare double @llvm.powi.f64(double %Val, i32 %power)
5623 declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
5624 declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
5625 declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %Val, i32 %power)
5631 The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
5632 specified (positive or negative) power. The order of evaluation of
5633 multiplications is not defined. When a vector of floating point type is
5634 used, the second argument remains a scalar integer value.
5640 The second argument is an integer power, and the first is a value to raise to
5647 This function returns the first value raised to the second power with an
5648 unspecified sequence of rounding operations.</p>
5651 <!-- _______________________________________________________________________ -->
5652 <div class="doc_subsubsection">
5653 <a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
5656 <div class="doc_text">
5659 <p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
5660 floating point or vector of floating point type. Not all targets support all
5663 declare float @llvm.sin.f32(float %Val)
5664 declare double @llvm.sin.f64(double %Val)
5665 declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
5666 declare fp128 @llvm.sin.f128(fp128 %Val)
5667 declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
5673 The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.
5679 The argument and return value are floating point numbers of the same type.
5685 This function returns the sine of the specified operand, returning the
5686 same values as the libm <tt>sin</tt> functions would, and handles error
5687 conditions in the same way.</p>
5690 <!-- _______________________________________________________________________ -->
5691 <div class="doc_subsubsection">
5692 <a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
5695 <div class="doc_text">
5698 <p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
5699 floating point or vector of floating point type. Not all targets support all
5702 declare float @llvm.cos.f32(float %Val)
5703 declare double @llvm.cos.f64(double %Val)
5704 declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
5705 declare fp128 @llvm.cos.f128(fp128 %Val)
5706 declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
5712 The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.
5718 The argument and return value are floating point numbers of the same type.
5724 This function returns the cosine of the specified operand, returning the
5725 same values as the libm <tt>cos</tt> functions would, and handles error
5726 conditions in the same way.</p>
5729 <!-- _______________________________________________________________________ -->
5730 <div class="doc_subsubsection">
5731 <a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
5734 <div class="doc_text">
5737 <p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
5738 floating point or vector of floating point type. Not all targets support all
5741 declare float @llvm.pow.f32(float %Val, float %Power)
5742 declare double @llvm.pow.f64(double %Val, double %Power)
5743 declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
5744 declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
5745 declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
5751 The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
5752 specified (positive or negative) power.
5758 The second argument is a floating point power, and the first is a value to
5759 raise to that power.
5765 This function returns the first value raised to the second power,
5767 same values as the libm <tt>pow</tt> functions would, and handles error
5768 conditions in the same way.</p>
5772 <!-- ======================================================================= -->
5773 <div class="doc_subsection">
5774 <a name="int_manip">Bit Manipulation Intrinsics</a>
5777 <div class="doc_text">
5779 LLVM provides intrinsics for a few important bit manipulation operations.
5780 These allow efficient code generation for some algorithms.
5785 <!-- _______________________________________________________________________ -->
5786 <div class="doc_subsubsection">
5787 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
5790 <div class="doc_text">
5793 <p>This is an overloaded intrinsic function. You can use bswap on any integer
5794 type that is an even number of bytes (i.e. BitWidth % 16 == 0).</p>
5796 declare i16 @llvm.bswap.i16(i16 <id>)
5797 declare i32 @llvm.bswap.i32(i32 <id>)
5798 declare i64 @llvm.bswap.i64(i64 <id>)
5804 The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
5805 values with an even number of bytes (positive multiple of 16 bits). These are
5806 useful for performing operations on data that is not in the target's native
5813 The <tt>llvm.bswap.i16</tt> intrinsic returns an i16 value that has the high
5814 and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
5815 intrinsic returns an i32 value that has the four bytes of the input i32
5816 swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
5817 i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48</tt>,
5818 <tt>llvm.bswap.i64</tt> and other intrinsics extend this concept to
5819 additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
5824 <!-- _______________________________________________________________________ -->
5825 <div class="doc_subsubsection">
5826 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
5829 <div class="doc_text">
5832 <p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
5833 width. Not all targets support all bit widths however.</p>
5835 declare i8 @llvm.ctpop.i8(i8 <src>)
5836 declare i16 @llvm.ctpop.i16(i16 <src>)
5837 declare i32 @llvm.ctpop.i32(i32 <src>)
5838 declare i64 @llvm.ctpop.i64(i64 <src>)
5839 declare i256 @llvm.ctpop.i256(i256 <src>)
5845 The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
5852 The only argument is the value to be counted. The argument may be of any
5853 integer type. The return type must match the argument type.
5859 The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
5863 <!-- _______________________________________________________________________ -->
5864 <div class="doc_subsubsection">
5865 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
5868 <div class="doc_text">
5871 <p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
5872 integer bit width. Not all targets support all bit widths however.</p>
5874 declare i8 @llvm.ctlz.i8 (i8 <src>)
5875 declare i16 @llvm.ctlz.i16(i16 <src>)
5876 declare i32 @llvm.ctlz.i32(i32 <src>)
5877 declare i64 @llvm.ctlz.i64(i64 <src>)
5878 declare i256 @llvm.ctlz.i256(i256 <src>)
5884 The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
5885 leading zeros in a variable.
5891 The only argument is the value to be counted. The argument may be of any
5892 integer type. The return type must match the argument type.
5898 The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
5899 in a variable. If the src == 0 then the result is the size in bits of the type
5900 of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
5906 <!-- _______________________________________________________________________ -->
5907 <div class="doc_subsubsection">
5908 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
5911 <div class="doc_text">
5914 <p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
5915 integer bit width. Not all targets support all bit widths however.</p>
5917 declare i8 @llvm.cttz.i8 (i8 <src>)
5918 declare i16 @llvm.cttz.i16(i16 <src>)
5919 declare i32 @llvm.cttz.i32(i32 <src>)
5920 declare i64 @llvm.cttz.i64(i64 <src>)
5921 declare i256 @llvm.cttz.i256(i256 <src>)
5927 The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
5934 The only argument is the value to be counted. The argument may be of any
5935 integer type. The return type must match the argument type.
5941 The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
5942 in a variable. If the src == 0 then the result is the size in bits of the type
5943 of src. For example, <tt>llvm.cttz(2) = 1</tt>.
5948 <!-- ======================================================================= -->
5949 <div class="doc_subsection">
5950 <a name="int_overflow">Arithmetic with Overflow Intrinsics</a>
5953 <div class="doc_text">
5955 LLVM provides intrinsics for some arithmetic with overflow operations.
5960 <!-- _______________________________________________________________________ -->
5961 <div class="doc_subsubsection">
5962 <a name="int_sadd_overflow">'<tt>llvm.sadd.with.overflow.*</tt>' Intrinsics</a>
5965 <div class="doc_text">
5969 <p>This is an overloaded intrinsic. You can use <tt>llvm.sadd.with.overflow</tt>
5970 on any integer bit width.</p>
5973 declare {i16, i1} @llvm.sadd.with.overflow.i16(i16 %a, i16 %b)
5974 declare {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
5975 declare {i64, i1} @llvm.sadd.with.overflow.i64(i64 %a, i64 %b)
5980 <p>The '<tt>llvm.sadd.with.overflow</tt>' family of intrinsic functions perform
5981 a signed addition of the two arguments, and indicate whether an overflow
5982 occurred during the signed summation.</p>
5986 <p>The arguments (%a and %b) and the first element of the result structure may
5987 be of integer types of any bit width, but they must have the same bit width. The
5988 second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
5989 and <tt>%b</tt> are the two values that will undergo signed addition.</p>
5993 <p>The '<tt>llvm.sadd.with.overflow</tt>' family of intrinsic functions perform
5994 a signed addition of the two variables. They return a structure — the
5995 first element of which is the signed summation, and the second element of which
5996 is a bit specifying if the signed summation resulted in an overflow.</p>
6000 %res = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
6001 %sum = extractvalue {i32, i1} %res, 0
6002 %obit = extractvalue {i32, i1} %res, 1
6003 br i1 %obit, label %overflow, label %normal
6008 <!-- _______________________________________________________________________ -->
6009 <div class="doc_subsubsection">
6010 <a name="int_uadd_overflow">'<tt>llvm.uadd.with.overflow.*</tt>' Intrinsics</a>
6013 <div class="doc_text">
6017 <p>This is an overloaded intrinsic. You can use <tt>llvm.uadd.with.overflow</tt>
6018 on any integer bit width.</p>
6021 declare {i16, i1} @llvm.uadd.with.overflow.i16(i16 %a, i16 %b)
6022 declare {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
6023 declare {i64, i1} @llvm.uadd.with.overflow.i64(i64 %a, i64 %b)
6028 <p>The '<tt>llvm.uadd.with.overflow</tt>' family of intrinsic functions perform
6029 an unsigned addition of the two arguments, and indicate whether a carry occurred
6030 during the unsigned summation.</p>
6034 <p>The arguments (%a and %b) and the first element of the result structure may
6035 be of integer types of any bit width, but they must have the same bit width. The
6036 second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
6037 and <tt>%b</tt> are the two values that will undergo unsigned addition.</p>
6041 <p>The '<tt>llvm.uadd.with.overflow</tt>' family of intrinsic functions perform
6042 an unsigned addition of the two arguments. They return a structure — the
6043 first element of which is the sum, and the second element of which is a bit
6044 specifying if the unsigned summation resulted in a carry.</p>
6048 %res = call {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
6049 %sum = extractvalue {i32, i1} %res, 0
6050 %obit = extractvalue {i32, i1} %res, 1
6051 br i1 %obit, label %carry, label %normal
6056 <!-- _______________________________________________________________________ -->
6057 <div class="doc_subsubsection">
6058 <a name="int_ssub_overflow">'<tt>llvm.ssub.with.overflow.*</tt>' Intrinsics</a>
6061 <div class="doc_text">
6065 <p>This is an overloaded intrinsic. You can use <tt>llvm.ssub.with.overflow</tt>
6066 on any integer bit width.</p>
6069 declare {i16, i1} @llvm.ssub.with.overflow.i16(i16 %a, i16 %b)
6070 declare {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
6071 declare {i64, i1} @llvm.ssub.with.overflow.i64(i64 %a, i64 %b)
6076 <p>The '<tt>llvm.ssub.with.overflow</tt>' family of intrinsic functions perform
6077 a signed subtraction of the two arguments, and indicate whether an overflow
6078 occurred during the signed subtraction.</p>
6082 <p>The arguments (%a and %b) and the first element of the result structure may
6083 be of integer types of any bit width, but they must have the same bit width. The
6084 second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
6085 and <tt>%b</tt> are the two values that will undergo signed subtraction.</p>
6089 <p>The '<tt>llvm.ssub.with.overflow</tt>' family of intrinsic functions perform
6090 a signed subtraction of the two arguments. They return a structure — the
6091 first element of which is the subtraction, and the second element of which is a bit
6092 specifying if the signed subtraction resulted in an overflow.</p>
6096 %res = call {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
6097 %sum = extractvalue {i32, i1} %res, 0
6098 %obit = extractvalue {i32, i1} %res, 1
6099 br i1 %obit, label %overflow, label %normal
6104 <!-- _______________________________________________________________________ -->
6105 <div class="doc_subsubsection">
6106 <a name="int_usub_overflow">'<tt>llvm.usub.with.overflow.*</tt>' Intrinsics</a>
6109 <div class="doc_text">
6113 <p>This is an overloaded intrinsic. You can use <tt>llvm.usub.with.overflow</tt>
6114 on any integer bit width.</p>
6117 declare {i16, i1} @llvm.usub.with.overflow.i16(i16 %a, i16 %b)
6118 declare {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
6119 declare {i64, i1} @llvm.usub.with.overflow.i64(i64 %a, i64 %b)
6124 <p>The '<tt>llvm.usub.with.overflow</tt>' family of intrinsic functions perform
6125 an unsigned subtraction of the two arguments, and indicate whether an overflow
6126 occurred during the unsigned subtraction.</p>
6130 <p>The arguments (%a and %b) and the first element of the result structure may
6131 be of integer types of any bit width, but they must have the same bit width. The
6132 second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
6133 and <tt>%b</tt> are the two values that will undergo unsigned subtraction.</p>
6137 <p>The '<tt>llvm.usub.with.overflow</tt>' family of intrinsic functions perform
6138 an unsigned subtraction of the two arguments. They return a structure — the
6139 first element of which is the subtraction, and the second element of which is a bit
6140 specifying if the unsigned subtraction resulted in an overflow.</p>
6144 %res = call {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
6145 %sum = extractvalue {i32, i1} %res, 0
6146 %obit = extractvalue {i32, i1} %res, 1
6147 br i1 %obit, label %overflow, label %normal
6152 <!-- _______________________________________________________________________ -->
6153 <div class="doc_subsubsection">
6154 <a name="int_smul_overflow">'<tt>llvm.smul.with.overflow.*</tt>' Intrinsics</a>
6157 <div class="doc_text">
6161 <p>This is an overloaded intrinsic. You can use <tt>llvm.smul.with.overflow</tt>
6162 on any integer bit width.</p>
6165 declare {i16, i1} @llvm.smul.with.overflow.i16(i16 %a, i16 %b)
6166 declare {i32, i1} @llvm.smul.with.overflow.i32(i32 %a, i32 %b)
6167 declare {i64, i1} @llvm.smul.with.overflow.i64(i64 %a, i64 %b)
6172 <p>The '<tt>llvm.smul.with.overflow</tt>' family of intrinsic functions perform
6173 a signed multiplication of the two arguments, and indicate whether an overflow
6174 occurred during the signed multiplication.</p>
6178 <p>The arguments (%a and %b) and the first element of the result structure may
6179 be of integer types of any bit width, but they must have the same bit width. The
6180 second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
6181 and <tt>%b</tt> are the two values that will undergo signed multiplication.</p>
6185 <p>The '<tt>llvm.smul.with.overflow</tt>' family of intrinsic functions perform
6186 a signed multiplication of the two arguments. They return a structure —
6187 the first element of which is the multiplication, and the second element of
6188 which is a bit specifying if the signed multiplication resulted in an
6193 %res = call {i32, i1} @llvm.smul.with.overflow.i32(i32 %a, i32 %b)
6194 %sum = extractvalue {i32, i1} %res, 0
6195 %obit = extractvalue {i32, i1} %res, 1
6196 br i1 %obit, label %overflow, label %normal
6201 <!-- _______________________________________________________________________ -->
6202 <div class="doc_subsubsection">
6203 <a name="int_umul_overflow">'<tt>llvm.umul.with.overflow.*</tt>' Intrinsics</a>
6206 <div class="doc_text">
6210 <p>This is an overloaded intrinsic. You can use <tt>llvm.umul.with.overflow</tt>
6211 on any integer bit width.</p>
6214 declare {i16, i1} @llvm.umul.with.overflow.i16(i16 %a, i16 %b)
6215 declare {i32, i1} @llvm.umul.with.overflow.i32(i32 %a, i32 %b)
6216 declare {i64, i1} @llvm.umul.with.overflow.i64(i64 %a, i64 %b)
6221 <p>The '<tt>llvm.umul.with.overflow</tt>' family of intrinsic functions perform
6222 a unsigned multiplication of the two arguments, and indicate whether an overflow
6223 occurred during the unsigned multiplication.</p>
6227 <p>The arguments (%a and %b) and the first element of the result structure may
6228 be of integer types of any bit width, but they must have the same bit width. The
6229 second element of the result structure must be of type <tt>i1</tt>. <tt>%a</tt>
6230 and <tt>%b</tt> are the two values that will undergo unsigned
6235 <p>The '<tt>llvm.umul.with.overflow</tt>' family of intrinsic functions perform
6236 an unsigned multiplication of the two arguments. They return a structure —
6237 the first element of which is the multiplication, and the second element of
6238 which is a bit specifying if the unsigned multiplication resulted in an
6243 %res = call {i32, i1} @llvm.umul.with.overflow.i32(i32 %a, i32 %b)
6244 %sum = extractvalue {i32, i1} %res, 0
6245 %obit = extractvalue {i32, i1} %res, 1
6246 br i1 %obit, label %overflow, label %normal
6251 <!-- ======================================================================= -->
6252 <div class="doc_subsection">
6253 <a name="int_debugger">Debugger Intrinsics</a>
6256 <div class="doc_text">
6258 The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
6259 are described in the <a
6260 href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
6261 Debugging</a> document.
6266 <!-- ======================================================================= -->
6267 <div class="doc_subsection">
6268 <a name="int_eh">Exception Handling Intrinsics</a>
6271 <div class="doc_text">
6272 <p> The LLVM exception handling intrinsics (which all start with
6273 <tt>llvm.eh.</tt> prefix), are described in the <a
6274 href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
6275 Handling</a> document. </p>
6278 <!-- ======================================================================= -->
6279 <div class="doc_subsection">
6280 <a name="int_trampoline">Trampoline Intrinsic</a>
6283 <div class="doc_text">
6285 This intrinsic makes it possible to excise one parameter, marked with
6286 the <tt>nest</tt> attribute, from a function. The result is a callable
6287 function pointer lacking the nest parameter - the caller does not need
6288 to provide a value for it. Instead, the value to use is stored in
6289 advance in a "trampoline", a block of memory usually allocated
6290 on the stack, which also contains code to splice the nest value into the
6291 argument list. This is used to implement the GCC nested function address
6295 For example, if the function is
6296 <tt>i32 f(i8* nest %c, i32 %x, i32 %y)</tt> then the resulting function
6297 pointer has signature <tt>i32 (i32, i32)*</tt>. It can be created as follows:</p>
6299 %tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
6300 %tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
6301 %p = call i8* @llvm.init.trampoline( i8* %tramp1, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval )
6302 %fp = bitcast i8* %p to i32 (i32, i32)*
6304 <p>The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent
6305 to <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>.</p>
6308 <!-- _______________________________________________________________________ -->
6309 <div class="doc_subsubsection">
6310 <a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a>
6312 <div class="doc_text">
6315 declare i8* @llvm.init.trampoline(i8* <tramp>, i8* <func>, i8* <nval>)
6319 This fills the memory pointed to by <tt>tramp</tt> with code
6320 and returns a function pointer suitable for executing it.
6324 The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
6325 pointers. The <tt>tramp</tt> argument must point to a sufficiently large
6326 and sufficiently aligned block of memory; this memory is written to by the
6327 intrinsic. Note that the size and the alignment are target-specific - LLVM
6328 currently provides no portable way of determining them, so a front-end that
6329 generates this intrinsic needs to have some target-specific knowledge.
6330 The <tt>func</tt> argument must hold a function bitcast to an <tt>i8*</tt>.
6334 The block of memory pointed to by <tt>tramp</tt> is filled with target
6335 dependent code, turning it into a function. A pointer to this function is
6336 returned, but needs to be bitcast to an
6337 <a href="#int_trampoline">appropriate function pointer type</a>
6338 before being called. The new function's signature is the same as that of
6339 <tt>func</tt> with any arguments marked with the <tt>nest</tt> attribute
6340 removed. At most one such <tt>nest</tt> argument is allowed, and it must be
6341 of pointer type. Calling the new function is equivalent to calling
6342 <tt>func</tt> with the same argument list, but with <tt>nval</tt> used for the
6343 missing <tt>nest</tt> argument. If, after calling
6344 <tt>llvm.init.trampoline</tt>, the memory pointed to by <tt>tramp</tt> is
6345 modified, then the effect of any later call to the returned function pointer is
6350 <!-- ======================================================================= -->
6351 <div class="doc_subsection">
6352 <a name="int_atomics">Atomic Operations and Synchronization Intrinsics</a>
6355 <div class="doc_text">
6357 These intrinsic functions expand the "universal IR" of LLVM to represent
6358 hardware constructs for atomic operations and memory synchronization. This
6359 provides an interface to the hardware, not an interface to the programmer. It
6360 is aimed at a low enough level to allow any programming models or APIs
6361 (Application Programming Interfaces) which
6362 need atomic behaviors to map cleanly onto it. It is also modeled primarily on
6363 hardware behavior. Just as hardware provides a "universal IR" for source
6364 languages, it also provides a starting point for developing a "universal"
6365 atomic operation and synchronization IR.
6368 These do <em>not</em> form an API such as high-level threading libraries,
6369 software transaction memory systems, atomic primitives, and intrinsic
6370 functions as found in BSD, GNU libc, atomic_ops, APR, and other system and
6371 application libraries. The hardware interface provided by LLVM should allow
6372 a clean implementation of all of these APIs and parallel programming models.
6373 No one model or paradigm should be selected above others unless the hardware
6374 itself ubiquitously does so.
6379 <!-- _______________________________________________________________________ -->
6380 <div class="doc_subsubsection">
6381 <a name="int_memory_barrier">'<tt>llvm.memory.barrier</tt>' Intrinsic</a>
6383 <div class="doc_text">
6386 declare void @llvm.memory.barrier( i1 <ll>, i1 <ls>, i1 <sl>, i1 <ss>,
6392 The <tt>llvm.memory.barrier</tt> intrinsic guarantees ordering between
6393 specific pairs of memory access types.
6397 The <tt>llvm.memory.barrier</tt> intrinsic requires five boolean arguments.
6398 The first four arguments enables a specific barrier as listed below. The fith
6399 argument specifies that the barrier applies to io or device or uncached memory.
6403 <li><tt>ll</tt>: load-load barrier</li>
6404 <li><tt>ls</tt>: load-store barrier</li>
6405 <li><tt>sl</tt>: store-load barrier</li>
6406 <li><tt>ss</tt>: store-store barrier</li>
6407 <li><tt>device</tt>: barrier applies to device and uncached memory also.</li>
6411 This intrinsic causes the system to enforce some ordering constraints upon
6412 the loads and stores of the program. This barrier does not indicate
6413 <em>when</em> any events will occur, it only enforces an <em>order</em> in
6414 which they occur. For any of the specified pairs of load and store operations
6415 (f.ex. load-load, or store-load), all of the first operations preceding the
6416 barrier will complete before any of the second operations succeeding the
6417 barrier begin. Specifically the semantics for each pairing is as follows:
6420 <li><tt>ll</tt>: All loads before the barrier must complete before any load
6421 after the barrier begins.</li>
6423 <li><tt>ls</tt>: All loads before the barrier must complete before any
6424 store after the barrier begins.</li>
6425 <li><tt>ss</tt>: All stores before the barrier must complete before any
6426 store after the barrier begins.</li>
6427 <li><tt>sl</tt>: All stores before the barrier must complete before any
6428 load after the barrier begins.</li>
6431 These semantics are applied with a logical "and" behavior when more than one
6432 is enabled in a single memory barrier intrinsic.
6435 Backends may implement stronger barriers than those requested when they do not
6436 support as fine grained a barrier as requested. Some architectures do not
6437 need all types of barriers and on such architectures, these become noops.
6444 %result1 = load i32* %ptr <i>; yields {i32}:result1 = 4</i>
6445 call void @llvm.memory.barrier( i1 false, i1 true, i1 false, i1 false )
6446 <i>; guarantee the above finishes</i>
6447 store i32 8, %ptr <i>; before this begins</i>
6451 <!-- _______________________________________________________________________ -->
6452 <div class="doc_subsubsection">
6453 <a name="int_atomic_cmp_swap">'<tt>llvm.atomic.cmp.swap.*</tt>' Intrinsic</a>
6455 <div class="doc_text">
6458 This is an overloaded intrinsic. You can use <tt>llvm.atomic.cmp.swap</tt> on
6459 any integer bit width and for different address spaces. Not all targets
6460 support all bit widths however.</p>
6463 declare i8 @llvm.atomic.cmp.swap.i8.p0i8( i8* <ptr>, i8 <cmp>, i8 <val> )
6464 declare i16 @llvm.atomic.cmp.swap.i16.p0i16( i16* <ptr>, i16 <cmp>, i16 <val> )
6465 declare i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* <ptr>, i32 <cmp>, i32 <val> )
6466 declare i64 @llvm.atomic.cmp.swap.i64.p0i64( i64* <ptr>, i64 <cmp>, i64 <val> )
6471 This loads a value in memory and compares it to a given value. If they are
6472 equal, it stores a new value into the memory.
6476 The <tt>llvm.atomic.cmp.swap</tt> intrinsic takes three arguments. The result as
6477 well as both <tt>cmp</tt> and <tt>val</tt> must be integer values with the
6478 same bit width. The <tt>ptr</tt> argument must be a pointer to a value of
6479 this integer type. While any bit width integer may be used, targets may only
6480 lower representations they support in hardware.
6485 This entire intrinsic must be executed atomically. It first loads the value
6486 in memory pointed to by <tt>ptr</tt> and compares it with the value
6487 <tt>cmp</tt>. If they are equal, <tt>val</tt> is stored into the memory. The
6488 loaded value is yielded in all cases. This provides the equivalent of an
6489 atomic compare-and-swap operation within the SSA framework.
6497 %val1 = add i32 4, 4
6498 %result1 = call i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* %ptr, i32 4, %val1 )
6499 <i>; yields {i32}:result1 = 4</i>
6500 %stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
6501 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
6503 %val2 = add i32 1, 1
6504 %result2 = call i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* %ptr, i32 5, %val2 )
6505 <i>; yields {i32}:result2 = 8</i>
6506 %stored2 = icmp eq i32 %result2, 5 <i>; yields {i1}:stored2 = false</i>
6508 %memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 8</i>
6512 <!-- _______________________________________________________________________ -->
6513 <div class="doc_subsubsection">
6514 <a name="int_atomic_swap">'<tt>llvm.atomic.swap.*</tt>' Intrinsic</a>
6516 <div class="doc_text">
6520 This is an overloaded intrinsic. You can use <tt>llvm.atomic.swap</tt> on any
6521 integer bit width. Not all targets support all bit widths however.</p>
6523 declare i8 @llvm.atomic.swap.i8.p0i8( i8* <ptr>, i8 <val> )
6524 declare i16 @llvm.atomic.swap.i16.p0i16( i16* <ptr>, i16 <val> )
6525 declare i32 @llvm.atomic.swap.i32.p0i32( i32* <ptr>, i32 <val> )
6526 declare i64 @llvm.atomic.swap.i64.p0i64( i64* <ptr>, i64 <val> )
6531 This intrinsic loads the value stored in memory at <tt>ptr</tt> and yields
6532 the value from memory. It then stores the value in <tt>val</tt> in the memory
6538 The <tt>llvm.atomic.swap</tt> intrinsic takes two arguments. Both the
6539 <tt>val</tt> argument and the result must be integers of the same bit width.
6540 The first argument, <tt>ptr</tt>, must be a pointer to a value of this
6541 integer type. The targets may only lower integer representations they
6546 This intrinsic loads the value pointed to by <tt>ptr</tt>, yields it, and
6547 stores <tt>val</tt> back into <tt>ptr</tt> atomically. This provides the
6548 equivalent of an atomic swap operation within the SSA framework.
6556 %val1 = add i32 4, 4
6557 %result1 = call i32 @llvm.atomic.swap.i32.p0i32( i32* %ptr, i32 %val1 )
6558 <i>; yields {i32}:result1 = 4</i>
6559 %stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
6560 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
6562 %val2 = add i32 1, 1
6563 %result2 = call i32 @llvm.atomic.swap.i32.p0i32( i32* %ptr, i32 %val2 )
6564 <i>; yields {i32}:result2 = 8</i>
6566 %stored2 = icmp eq i32 %result2, 8 <i>; yields {i1}:stored2 = true</i>
6567 %memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 2</i>
6571 <!-- _______________________________________________________________________ -->
6572 <div class="doc_subsubsection">
6573 <a name="int_atomic_load_add">'<tt>llvm.atomic.load.add.*</tt>' Intrinsic</a>
6576 <div class="doc_text">
6579 This is an overloaded intrinsic. You can use <tt>llvm.atomic.load.add</tt> on any
6580 integer bit width. Not all targets support all bit widths however.</p>
6582 declare i8 @llvm.atomic.load.add.i8..p0i8( i8* <ptr>, i8 <delta> )
6583 declare i16 @llvm.atomic.load.add.i16..p0i16( i16* <ptr>, i16 <delta> )
6584 declare i32 @llvm.atomic.load.add.i32..p0i32( i32* <ptr>, i32 <delta> )
6585 declare i64 @llvm.atomic.load.add.i64..p0i64( i64* <ptr>, i64 <delta> )
6590 This intrinsic adds <tt>delta</tt> to the value stored in memory at
6591 <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
6596 The intrinsic takes two arguments, the first a pointer to an integer value
6597 and the second an integer value. The result is also an integer value. These
6598 integer types can have any bit width, but they must all have the same bit
6599 width. The targets may only lower integer representations they support.
6603 This intrinsic does a series of operations atomically. It first loads the
6604 value stored at <tt>ptr</tt>. It then adds <tt>delta</tt>, stores the result
6605 to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.
6612 %result1 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 4 )
6613 <i>; yields {i32}:result1 = 4</i>
6614 %result2 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 2 )
6615 <i>; yields {i32}:result2 = 8</i>
6616 %result3 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 5 )
6617 <i>; yields {i32}:result3 = 10</i>
6618 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 15</i>
6622 <!-- _______________________________________________________________________ -->
6623 <div class="doc_subsubsection">
6624 <a name="int_atomic_load_sub">'<tt>llvm.atomic.load.sub.*</tt>' Intrinsic</a>
6627 <div class="doc_text">
6630 This is an overloaded intrinsic. You can use <tt>llvm.atomic.load.sub</tt> on
6631 any integer bit width and for different address spaces. Not all targets
6632 support all bit widths however.</p>
6634 declare i8 @llvm.atomic.load.sub.i8.p0i32( i8* <ptr>, i8 <delta> )
6635 declare i16 @llvm.atomic.load.sub.i16.p0i32( i16* <ptr>, i16 <delta> )
6636 declare i32 @llvm.atomic.load.sub.i32.p0i32( i32* <ptr>, i32 <delta> )
6637 declare i64 @llvm.atomic.load.sub.i64.p0i32( i64* <ptr>, i64 <delta> )
6642 This intrinsic subtracts <tt>delta</tt> to the value stored in memory at
6643 <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
6648 The intrinsic takes two arguments, the first a pointer to an integer value
6649 and the second an integer value. The result is also an integer value. These
6650 integer types can have any bit width, but they must all have the same bit
6651 width. The targets may only lower integer representations they support.
6655 This intrinsic does a series of operations atomically. It first loads the
6656 value stored at <tt>ptr</tt>. It then subtracts <tt>delta</tt>, stores the
6657 result to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.
6664 %result1 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 4 )
6665 <i>; yields {i32}:result1 = 8</i>
6666 %result2 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 2 )
6667 <i>; yields {i32}:result2 = 4</i>
6668 %result3 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 5 )
6669 <i>; yields {i32}:result3 = 2</i>
6670 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = -3</i>
6674 <!-- _______________________________________________________________________ -->
6675 <div class="doc_subsubsection">
6676 <a name="int_atomic_load_and">'<tt>llvm.atomic.load.and.*</tt>' Intrinsic</a><br>
6677 <a name="int_atomic_load_nand">'<tt>llvm.atomic.load.nand.*</tt>' Intrinsic</a><br>
6678 <a name="int_atomic_load_or">'<tt>llvm.atomic.load.or.*</tt>' Intrinsic</a><br>
6679 <a name="int_atomic_load_xor">'<tt>llvm.atomic.load.xor.*</tt>' Intrinsic</a><br>
6682 <div class="doc_text">
6685 These are overloaded intrinsics. You can use <tt>llvm.atomic.load_and</tt>,
6686 <tt>llvm.atomic.load_nand</tt>, <tt>llvm.atomic.load_or</tt>, and
6687 <tt>llvm.atomic.load_xor</tt> on any integer bit width and for different
6688 address spaces. Not all targets support all bit widths however.</p>
6690 declare i8 @llvm.atomic.load.and.i8.p0i8( i8* <ptr>, i8 <delta> )
6691 declare i16 @llvm.atomic.load.and.i16.p0i16( i16* <ptr>, i16 <delta> )
6692 declare i32 @llvm.atomic.load.and.i32.p0i32( i32* <ptr>, i32 <delta> )
6693 declare i64 @llvm.atomic.load.and.i64.p0i64( i64* <ptr>, i64 <delta> )
6698 declare i8 @llvm.atomic.load.or.i8.p0i8( i8* <ptr>, i8 <delta> )
6699 declare i16 @llvm.atomic.load.or.i16.p0i16( i16* <ptr>, i16 <delta> )
6700 declare i32 @llvm.atomic.load.or.i32.p0i32( i32* <ptr>, i32 <delta> )
6701 declare i64 @llvm.atomic.load.or.i64.p0i64( i64* <ptr>, i64 <delta> )
6706 declare i8 @llvm.atomic.load.nand.i8.p0i32( i8* <ptr>, i8 <delta> )
6707 declare i16 @llvm.atomic.load.nand.i16.p0i32( i16* <ptr>, i16 <delta> )
6708 declare i32 @llvm.atomic.load.nand.i32.p0i32( i32* <ptr>, i32 <delta> )
6709 declare i64 @llvm.atomic.load.nand.i64.p0i32( i64* <ptr>, i64 <delta> )
6714 declare i8 @llvm.atomic.load.xor.i8.p0i32( i8* <ptr>, i8 <delta> )
6715 declare i16 @llvm.atomic.load.xor.i16.p0i32( i16* <ptr>, i16 <delta> )
6716 declare i32 @llvm.atomic.load.xor.i32.p0i32( i32* <ptr>, i32 <delta> )
6717 declare i64 @llvm.atomic.load.xor.i64.p0i32( i64* <ptr>, i64 <delta> )
6722 These intrinsics bitwise the operation (and, nand, or, xor) <tt>delta</tt> to
6723 the value stored in memory at <tt>ptr</tt>. It yields the original value
6729 These intrinsics take two arguments, the first a pointer to an integer value
6730 and the second an integer value. The result is also an integer value. These
6731 integer types can have any bit width, but they must all have the same bit
6732 width. The targets may only lower integer representations they support.
6736 These intrinsics does a series of operations atomically. They first load the
6737 value stored at <tt>ptr</tt>. They then do the bitwise operation
6738 <tt>delta</tt>, store the result to <tt>ptr</tt>. They yield the original
6739 value stored at <tt>ptr</tt>.
6745 store i32 0x0F0F, %ptr
6746 %result0 = call i32 @llvm.atomic.load.nand.i32.p0i32( i32* %ptr, i32 0xFF )
6747 <i>; yields {i32}:result0 = 0x0F0F</i>
6748 %result1 = call i32 @llvm.atomic.load.and.i32.p0i32( i32* %ptr, i32 0xFF )
6749 <i>; yields {i32}:result1 = 0xFFFFFFF0</i>
6750 %result2 = call i32 @llvm.atomic.load.or.i32.p0i32( i32* %ptr, i32 0F )
6751 <i>; yields {i32}:result2 = 0xF0</i>
6752 %result3 = call i32 @llvm.atomic.load.xor.i32.p0i32( i32* %ptr, i32 0F )
6753 <i>; yields {i32}:result3 = FF</i>
6754 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = F0</i>
6759 <!-- _______________________________________________________________________ -->
6760 <div class="doc_subsubsection">
6761 <a name="int_atomic_load_max">'<tt>llvm.atomic.load.max.*</tt>' Intrinsic</a><br>
6762 <a name="int_atomic_load_min">'<tt>llvm.atomic.load.min.*</tt>' Intrinsic</a><br>
6763 <a name="int_atomic_load_umax">'<tt>llvm.atomic.load.umax.*</tt>' Intrinsic</a><br>
6764 <a name="int_atomic_load_umin">'<tt>llvm.atomic.load.umin.*</tt>' Intrinsic</a><br>
6767 <div class="doc_text">
6770 These are overloaded intrinsics. You can use <tt>llvm.atomic.load_max</tt>,
6771 <tt>llvm.atomic.load_min</tt>, <tt>llvm.atomic.load_umax</tt>, and
6772 <tt>llvm.atomic.load_umin</tt> on any integer bit width and for different
6773 address spaces. Not all targets
6774 support all bit widths however.</p>
6776 declare i8 @llvm.atomic.load.max.i8.p0i8( i8* <ptr>, i8 <delta> )
6777 declare i16 @llvm.atomic.load.max.i16.p0i16( i16* <ptr>, i16 <delta> )
6778 declare i32 @llvm.atomic.load.max.i32.p0i32( i32* <ptr>, i32 <delta> )
6779 declare i64 @llvm.atomic.load.max.i64.p0i64( i64* <ptr>, i64 <delta> )
6784 declare i8 @llvm.atomic.load.min.i8.p0i8( i8* <ptr>, i8 <delta> )
6785 declare i16 @llvm.atomic.load.min.i16.p0i16( i16* <ptr>, i16 <delta> )
6786 declare i32 @llvm.atomic.load.min.i32..p0i32( i32* <ptr>, i32 <delta> )
6787 declare i64 @llvm.atomic.load.min.i64..p0i64( i64* <ptr>, i64 <delta> )
6792 declare i8 @llvm.atomic.load.umax.i8.p0i8( i8* <ptr>, i8 <delta> )
6793 declare i16 @llvm.atomic.load.umax.i16.p0i16( i16* <ptr>, i16 <delta> )
6794 declare i32 @llvm.atomic.load.umax.i32.p0i32( i32* <ptr>, i32 <delta> )
6795 declare i64 @llvm.atomic.load.umax.i64.p0i64( i64* <ptr>, i64 <delta> )
6800 declare i8 @llvm.atomic.load.umin.i8..p0i8( i8* <ptr>, i8 <delta> )
6801 declare i16 @llvm.atomic.load.umin.i16.p0i16( i16* <ptr>, i16 <delta> )
6802 declare i32 @llvm.atomic.load.umin.i32..p0i32( i32* <ptr>, i32 <delta> )
6803 declare i64 @llvm.atomic.load.umin.i64..p0i64( i64* <ptr>, i64 <delta> )
6808 These intrinsics takes the signed or unsigned minimum or maximum of
6809 <tt>delta</tt> and the value stored in memory at <tt>ptr</tt>. It yields the
6810 original value at <tt>ptr</tt>.
6815 These intrinsics take two arguments, the first a pointer to an integer value
6816 and the second an integer value. The result is also an integer value. These
6817 integer types can have any bit width, but they must all have the same bit
6818 width. The targets may only lower integer representations they support.
6822 These intrinsics does a series of operations atomically. They first load the
6823 value stored at <tt>ptr</tt>. They then do the signed or unsigned min or max
6824 <tt>delta</tt> and the value, store the result to <tt>ptr</tt>. They yield
6825 the original value stored at <tt>ptr</tt>.
6832 %result0 = call i32 @llvm.atomic.load.min.i32.p0i32( i32* %ptr, i32 -2 )
6833 <i>; yields {i32}:result0 = 7</i>
6834 %result1 = call i32 @llvm.atomic.load.max.i32.p0i32( i32* %ptr, i32 8 )
6835 <i>; yields {i32}:result1 = -2</i>
6836 %result2 = call i32 @llvm.atomic.load.umin.i32.p0i32( i32* %ptr, i32 10 )
6837 <i>; yields {i32}:result2 = 8</i>
6838 %result3 = call i32 @llvm.atomic.load.umax.i32.p0i32( i32* %ptr, i32 30 )
6839 <i>; yields {i32}:result3 = 8</i>
6840 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 30</i>
6844 <!-- ======================================================================= -->
6845 <div class="doc_subsection">
6846 <a name="int_general">General Intrinsics</a>
6849 <div class="doc_text">
6850 <p> This class of intrinsics is designed to be generic and has
6851 no specific purpose. </p>
6854 <!-- _______________________________________________________________________ -->
6855 <div class="doc_subsubsection">
6856 <a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
6859 <div class="doc_text">
6863 declare void @llvm.var.annotation(i8* <val>, i8* <str>, i8* <str>, i32 <int> )
6869 The '<tt>llvm.var.annotation</tt>' intrinsic
6875 The first argument is a pointer to a value, the second is a pointer to a
6876 global string, the third is a pointer to a global string which is the source
6877 file name, and the last argument is the line number.
6883 This intrinsic allows annotation of local variables with arbitrary strings.
6884 This can be useful for special purpose optimizations that want to look for these
6885 annotations. These have no other defined use, they are ignored by code
6886 generation and optimization.
6890 <!-- _______________________________________________________________________ -->
6891 <div class="doc_subsubsection">
6892 <a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
6895 <div class="doc_text">
6898 <p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
6899 any integer bit width.
6902 declare i8 @llvm.annotation.i8(i8 <val>, i8* <str>, i8* <str>, i32 <int> )
6903 declare i16 @llvm.annotation.i16(i16 <val>, i8* <str>, i8* <str>, i32 <int> )
6904 declare i32 @llvm.annotation.i32(i32 <val>, i8* <str>, i8* <str>, i32 <int> )
6905 declare i64 @llvm.annotation.i64(i64 <val>, i8* <str>, i8* <str>, i32 <int> )
6906 declare i256 @llvm.annotation.i256(i256 <val>, i8* <str>, i8* <str>, i32 <int> )
6912 The '<tt>llvm.annotation</tt>' intrinsic.
6918 The first argument is an integer value (result of some expression),
6919 the second is a pointer to a global string, the third is a pointer to a global
6920 string which is the source file name, and the last argument is the line number.
6921 It returns the value of the first argument.
6927 This intrinsic allows annotations to be put on arbitrary expressions
6928 with arbitrary strings. This can be useful for special purpose optimizations
6929 that want to look for these annotations. These have no other defined use, they
6930 are ignored by code generation and optimization.
6934 <!-- _______________________________________________________________________ -->
6935 <div class="doc_subsubsection">
6936 <a name="int_trap">'<tt>llvm.trap</tt>' Intrinsic</a>
6939 <div class="doc_text">
6943 declare void @llvm.trap()
6949 The '<tt>llvm.trap</tt>' intrinsic
6961 This intrinsics is lowered to the target dependent trap instruction. If the
6962 target does not have a trap instruction, this intrinsic will be lowered to the
6963 call of the abort() function.
6967 <!-- _______________________________________________________________________ -->
6968 <div class="doc_subsubsection">
6969 <a name="int_stackprotector">'<tt>llvm.stackprotector</tt>' Intrinsic</a>
6971 <div class="doc_text">
6974 declare void @llvm.stackprotector( i8* <guard>, i8** <slot> )
6979 The <tt>llvm.stackprotector</tt> intrinsic takes the <tt>guard</tt> and stores
6980 it onto the stack at <tt>slot</tt>. The stack slot is adjusted to ensure that
6981 it is placed on the stack before local variables.
6985 The <tt>llvm.stackprotector</tt> intrinsic requires two pointer arguments. The
6986 first argument is the value loaded from the stack guard
6987 <tt>@__stack_chk_guard</tt>. The second variable is an <tt>alloca</tt> that
6988 has enough space to hold the value of the guard.
6992 This intrinsic causes the prologue/epilogue inserter to force the position of
6993 the <tt>AllocaInst</tt> stack slot to be before local variables on the
6994 stack. This is to ensure that if a local variable on the stack is overwritten,
6995 it will destroy the value of the guard. When the function exits, the guard on
6996 the stack is checked against the original guard. If they're different, then
6997 the program aborts by calling the <tt>__stack_chk_fail()</tt> function.
7001 <!-- *********************************************************************** -->
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7009 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
7010 <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
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