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5 <title>LLVM Assembly Language Reference Manual</title>
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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="#globalvars">Global Variables</a></li>
26 <li><a href="#functionstructure">Functions</a></li>
27 <li><a href="#aliasstructure">Aliases</a>
28 <li><a href="#paramattrs">Parameter Attributes</a></li>
29 <li><a href="#gc">Garbage Collector Names</a></li>
30 <li><a href="#notes">Function Notes</a></li>
31 <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
32 <li><a href="#datalayout">Data Layout</a></li>
35 <li><a href="#typesystem">Type System</a>
37 <li><a href="#t_classifications">Type Classifications</a></li>
38 <li><a href="#t_primitive">Primitive Types</a>
40 <li><a href="#t_floating">Floating Point Types</a></li>
41 <li><a href="#t_void">Void Type</a></li>
42 <li><a href="#t_label">Label Type</a></li>
45 <li><a href="#t_derived">Derived Types</a>
47 <li><a href="#t_integer">Integer Type</a></li>
48 <li><a href="#t_array">Array Type</a></li>
49 <li><a href="#t_function">Function Type</a></li>
50 <li><a href="#t_pointer">Pointer Type</a></li>
51 <li><a href="#t_struct">Structure Type</a></li>
52 <li><a href="#t_pstruct">Packed Structure Type</a></li>
53 <li><a href="#t_vector">Vector Type</a></li>
54 <li><a href="#t_opaque">Opaque Type</a></li>
59 <li><a href="#constants">Constants</a>
61 <li><a href="#simpleconstants">Simple Constants</a>
62 <li><a href="#aggregateconstants">Aggregate Constants</a>
63 <li><a href="#globalconstants">Global Variable and Function Addresses</a>
64 <li><a href="#undefvalues">Undefined Values</a>
65 <li><a href="#constantexprs">Constant Expressions</a>
68 <li><a href="#othervalues">Other Values</a>
70 <li><a href="#inlineasm">Inline Assembler Expressions</a>
73 <li><a href="#instref">Instruction Reference</a>
75 <li><a href="#terminators">Terminator Instructions</a>
77 <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
78 <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
79 <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
80 <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
81 <li><a href="#i_unwind">'<tt>unwind</tt>' Instruction</a></li>
82 <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
85 <li><a href="#binaryops">Binary Operations</a>
87 <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
88 <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
89 <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
90 <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
91 <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
92 <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
93 <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
94 <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
95 <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
98 <li><a href="#bitwiseops">Bitwise Binary Operations</a>
100 <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
101 <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
102 <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
103 <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
104 <li><a href="#i_or">'<tt>or</tt>' Instruction</a></li>
105 <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
108 <li><a href="#vectorops">Vector Operations</a>
110 <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
111 <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
112 <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
115 <li><a href="#aggregateops">Aggregate Operations</a>
117 <li><a href="#i_extractvalue">'<tt>extractvalue</tt>' Instruction</a></li>
118 <li><a href="#i_insertvalue">'<tt>insertvalue</tt>' Instruction</a></li>
121 <li><a href="#memoryops">Memory Access and Addressing Operations</a>
123 <li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
124 <li><a href="#i_free">'<tt>free</tt>' Instruction</a></li>
125 <li><a href="#i_alloca">'<tt>alloca</tt>' Instruction</a></li>
126 <li><a href="#i_load">'<tt>load</tt>' Instruction</a></li>
127 <li><a href="#i_store">'<tt>store</tt>' Instruction</a></li>
128 <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
131 <li><a href="#convertops">Conversion Operations</a>
133 <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
134 <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
135 <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
136 <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
137 <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
138 <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
139 <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
140 <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
141 <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
142 <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
143 <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
144 <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
146 <li><a href="#otherops">Other Operations</a>
148 <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
149 <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
150 <li><a href="#i_vicmp">'<tt>vicmp</tt>' Instruction</a></li>
151 <li><a href="#i_vfcmp">'<tt>vfcmp</tt>' Instruction</a></li>
152 <li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
153 <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
154 <li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
155 <li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
156 <li><a href="#i_getresult">'<tt>getresult</tt>' Instruction</a></li>
161 <li><a href="#intrinsics">Intrinsic Functions</a>
163 <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
165 <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
166 <li><a href="#int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a></li>
167 <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a></li>
170 <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
172 <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
173 <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
174 <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
177 <li><a href="#int_codegen">Code Generator Intrinsics</a>
179 <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
180 <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a></li>
181 <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
182 <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
183 <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
184 <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
185 <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
188 <li><a href="#int_libc">Standard C Library Intrinsics</a>
190 <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
191 <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
192 <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
193 <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
194 <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
195 <li><a href="#int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a></li>
196 <li><a href="#int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a></li>
197 <li><a href="#int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a></li>
200 <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
202 <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
203 <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
204 <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
205 <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
206 <li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
207 <li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
210 <li><a href="#int_debugger">Debugger intrinsics</a></li>
211 <li><a href="#int_eh">Exception Handling intrinsics</a></li>
212 <li><a href="#int_trampoline">Trampoline Intrinsic</a>
214 <li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li>
217 <li><a href="#int_atomics">Atomic intrinsics</a>
219 <li><a href="#int_memory_barrier"><tt>llvm.memory_barrier</tt></a></li>
220 <li><a href="#int_atomic_cmp_swap"><tt>llvm.atomic.cmp.swap</tt></a></li>
221 <li><a href="#int_atomic_swap"><tt>llvm.atomic.swap</tt></a></li>
222 <li><a href="#int_atomic_load_add"><tt>llvm.atomic.load.add</tt></a></li>
223 <li><a href="#int_atomic_load_sub"><tt>llvm.atomic.load.sub</tt></a></li>
224 <li><a href="#int_atomic_load_and"><tt>llvm.atomic.load.and</tt></a></li>
225 <li><a href="#int_atomic_load_nand"><tt>llvm.atomic.load.nand</tt></a></li>
226 <li><a href="#int_atomic_load_or"><tt>llvm.atomic.load.or</tt></a></li>
227 <li><a href="#int_atomic_load_xor"><tt>llvm.atomic.load.xor</tt></a></li>
228 <li><a href="#int_atomic_load_max"><tt>llvm.atomic.load.max</tt></a></li>
229 <li><a href="#int_atomic_load_min"><tt>llvm.atomic.load.min</tt></a></li>
230 <li><a href="#int_atomic_load_umax"><tt>llvm.atomic.load.umax</tt></a></li>
231 <li><a href="#int_atomic_load_umin"><tt>llvm.atomic.load.umin</tt></a></li>
234 <li><a href="#int_general">General intrinsics</a>
236 <li><a href="#int_var_annotation">
237 <tt>llvm.var.annotation</tt>' Intrinsic</a></li>
238 <li><a href="#int_annotation">
239 <tt>llvm.annotation.*</tt>' Intrinsic</a></li>
240 <li><a href="#int_trap">
241 <tt>llvm.trap</tt>' Intrinsic</a></li>
248 <div class="doc_author">
249 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
250 and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
253 <!-- *********************************************************************** -->
254 <div class="doc_section"> <a name="abstract">Abstract </a></div>
255 <!-- *********************************************************************** -->
257 <div class="doc_text">
258 <p>This document is a reference manual for the LLVM assembly language.
259 LLVM is a Static Single Assignment (SSA) based representation that provides
260 type safety, low-level operations, flexibility, and the capability of
261 representing 'all' high-level languages cleanly. It is the common code
262 representation used throughout all phases of the LLVM compilation
266 <!-- *********************************************************************** -->
267 <div class="doc_section"> <a name="introduction">Introduction</a> </div>
268 <!-- *********************************************************************** -->
270 <div class="doc_text">
272 <p>The LLVM code representation is designed to be used in three
273 different forms: as an in-memory compiler IR, as an on-disk bitcode
274 representation (suitable for fast loading by a Just-In-Time compiler),
275 and as a human readable assembly language representation. This allows
276 LLVM to provide a powerful intermediate representation for efficient
277 compiler transformations and analysis, while providing a natural means
278 to debug and visualize the transformations. The three different forms
279 of LLVM are all equivalent. This document describes the human readable
280 representation and notation.</p>
282 <p>The LLVM representation aims to be light-weight and low-level
283 while being expressive, typed, and extensible at the same time. It
284 aims to be a "universal IR" of sorts, by being at a low enough level
285 that high-level ideas may be cleanly mapped to it (similar to how
286 microprocessors are "universal IR's", allowing many source languages to
287 be mapped to them). By providing type information, LLVM can be used as
288 the target of optimizations: for example, through pointer analysis, it
289 can be proven that a C automatic variable is never accessed outside of
290 the current function... allowing it to be promoted to a simple SSA
291 value instead of a memory location.</p>
295 <!-- _______________________________________________________________________ -->
296 <div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>
298 <div class="doc_text">
300 <p>It is important to note that this document describes 'well formed'
301 LLVM assembly language. There is a difference between what the parser
302 accepts and what is considered 'well formed'. For example, the
303 following instruction is syntactically okay, but not well formed:</p>
305 <div class="doc_code">
307 %x = <a href="#i_add">add</a> i32 1, %x
311 <p>...because the definition of <tt>%x</tt> does not dominate all of
312 its uses. The LLVM infrastructure provides a verification pass that may
313 be used to verify that an LLVM module is well formed. This pass is
314 automatically run by the parser after parsing input assembly and by
315 the optimizer before it outputs bitcode. The violations pointed out
316 by the verifier pass indicate bugs in transformation passes or input to
320 <!-- Describe the typesetting conventions here. -->
322 <!-- *********************************************************************** -->
323 <div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
324 <!-- *********************************************************************** -->
326 <div class="doc_text">
328 <p>LLVM identifiers come in two basic types: global and local. Global
329 identifiers (functions, global variables) begin with the @ character. Local
330 identifiers (register names, types) begin with the % character. Additionally,
331 there are three different formats for identifiers, for different purposes:
334 <li>Named values are represented as a string of characters with their prefix.
335 For example, %foo, @DivisionByZero, %a.really.long.identifier. The actual
336 regular expression used is '<tt>[%@][a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
337 Identifiers which require other characters in their names can be surrounded
338 with quotes. In this way, anything except a <tt>"</tt> character can
339 be used in a named value.</li>
341 <li>Unnamed values are represented as an unsigned numeric value with their
342 prefix. For example, %12, @2, %44.</li>
344 <li>Constants, which are described in a <a href="#constants">section about
345 constants</a>, below.</li>
348 <p>LLVM requires that values start with a prefix for two reasons: Compilers
349 don't need to worry about name clashes with reserved words, and the set of
350 reserved words may be expanded in the future without penalty. Additionally,
351 unnamed identifiers allow a compiler to quickly come up with a temporary
352 variable without having to avoid symbol table conflicts.</p>
354 <p>Reserved words in LLVM are very similar to reserved words in other
355 languages. There are keywords for different opcodes
356 ('<tt><a href="#i_add">add</a></tt>',
357 '<tt><a href="#i_bitcast">bitcast</a></tt>',
358 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
359 href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
360 and others. These reserved words cannot conflict with variable names, because
361 none of them start with a prefix character ('%' or '@').</p>
363 <p>Here is an example of LLVM code to multiply the integer variable
364 '<tt>%X</tt>' by 8:</p>
368 <div class="doc_code">
370 %result = <a href="#i_mul">mul</a> i32 %X, 8
374 <p>After strength reduction:</p>
376 <div class="doc_code">
378 %result = <a href="#i_shl">shl</a> i32 %X, i8 3
382 <p>And the hard way:</p>
384 <div class="doc_code">
386 <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
387 <a href="#i_add">add</a> i32 %0, %0 <i>; yields {i32}:%1</i>
388 %result = <a href="#i_add">add</a> i32 %1, %1
392 <p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
393 important lexical features of LLVM:</p>
397 <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
400 <li>Unnamed temporaries are created when the result of a computation is not
401 assigned to a named value.</li>
403 <li>Unnamed temporaries are numbered sequentially</li>
407 <p>...and it also shows a convention that we follow in this document. When
408 demonstrating instructions, we will follow an instruction with a comment that
409 defines the type and name of value produced. Comments are shown in italic
414 <!-- *********************************************************************** -->
415 <div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
416 <!-- *********************************************************************** -->
418 <!-- ======================================================================= -->
419 <div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
422 <div class="doc_text">
424 <p>LLVM programs are composed of "Module"s, each of which is a
425 translation unit of the input programs. Each module consists of
426 functions, global variables, and symbol table entries. Modules may be
427 combined together with the LLVM linker, which merges function (and
428 global variable) definitions, resolves forward declarations, and merges
429 symbol table entries. Here is an example of the "hello world" module:</p>
431 <div class="doc_code">
432 <pre><i>; Declare the string constant as a global constant...</i>
433 <a href="#identifiers">@.LC0</a> = <a href="#linkage_internal">internal</a> <a
434 href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00" <i>; [13 x i8]*</i>
436 <i>; External declaration of the puts function</i>
437 <a href="#functionstructure">declare</a> i32 @puts(i8 *) <i>; i32(i8 *)* </i>
439 <i>; Definition of main function</i>
440 define i32 @main() { <i>; i32()* </i>
441 <i>; Convert [13x i8 ]* to i8 *...</i>
443 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* @.LC0, i64 0, i64 0 <i>; i8 *</i>
445 <i>; Call puts function to write out the string to stdout...</i>
447 href="#i_call">call</a> i32 @puts(i8 * %cast210) <i>; i32</i>
449 href="#i_ret">ret</a> i32 0<br>}<br>
453 <p>This example is made up of a <a href="#globalvars">global variable</a>
454 named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
455 function, and a <a href="#functionstructure">function definition</a>
456 for "<tt>main</tt>".</p>
458 <p>In general, a module is made up of a list of global values,
459 where both functions and global variables are global values. Global values are
460 represented by a pointer to a memory location (in this case, a pointer to an
461 array of char, and a pointer to a function), and have one of the following <a
462 href="#linkage">linkage types</a>.</p>
466 <!-- ======================================================================= -->
467 <div class="doc_subsection">
468 <a name="linkage">Linkage Types</a>
471 <div class="doc_text">
474 All Global Variables and Functions have one of the following types of linkage:
479 <dt><tt><b><a name="linkage_internal">internal</a></b></tt>: </dt>
481 <dd>Global values with internal linkage are only directly accessible by
482 objects in the current module. In particular, linking code into a module with
483 an internal global value may cause the internal to be renamed as necessary to
484 avoid collisions. Because the symbol is internal to the module, all
485 references can be updated. This corresponds to the notion of the
486 '<tt>static</tt>' keyword in C.
489 <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>
491 <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
492 the same name when linkage occurs. This is typically used to implement
493 inline functions, templates, or other code which must be generated in each
494 translation unit that uses it. Unreferenced <tt>linkonce</tt> globals are
495 allowed to be discarded.
498 <dt><tt><b><a name="linkage_common">common</a></b></tt>: </dt>
500 <dd>"<tt>common</tt>" linkage is exactly the same as <tt>linkonce</tt>
501 linkage, except that unreferenced <tt>common</tt> globals may not be
502 discarded. This is used for globals that may be emitted in multiple
503 translation units, but that are not guaranteed to be emitted into every
504 translation unit that uses them. One example of this is tentative
505 definitions in C, such as "<tt>int X;</tt>" at global scope.
508 <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>
510 <dd>"<tt>weak</tt>" linkage is the same as <tt>common</tt> linkage, except
511 that some targets may choose to emit different assembly sequences for them
512 for target-dependent reasons. This is used for globals that are declared
513 "weak" in C source code.
516 <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>
518 <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
519 pointer to array type. When two global variables with appending linkage are
520 linked together, the two global arrays are appended together. This is the
521 LLVM, typesafe, equivalent of having the system linker append together
522 "sections" with identical names when .o files are linked.
525 <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
526 <dd>The semantics of this linkage follow the ELF object file model: the
527 symbol is weak until linked, if not linked, the symbol becomes null instead
528 of being an undefined reference.
531 <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>
533 <dd>If none of the above identifiers are used, the global is externally
534 visible, meaning that it participates in linkage and can be used to resolve
535 external symbol references.
540 The next two types of linkage are targeted for Microsoft Windows platform
541 only. They are designed to support importing (exporting) symbols from (to)
542 DLLs (Dynamic Link Libraries).
546 <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>
548 <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
549 or variable via a global pointer to a pointer that is set up by the DLL
550 exporting the symbol. On Microsoft Windows targets, the pointer name is
551 formed by combining <code>_imp__</code> and the function or variable name.
554 <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>
556 <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
557 pointer to a pointer in a DLL, so that it can be referenced with the
558 <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
559 name is formed by combining <code>_imp__</code> and the function or variable
565 <p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
566 variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
567 variable and was linked with this one, one of the two would be renamed,
568 preventing a collision. Since "<tt>main</tt>" and "<tt>puts</tt>" are
569 external (i.e., lacking any linkage declarations), they are accessible
570 outside of the current module.</p>
571 <p>It is illegal for a function <i>declaration</i>
572 to have any linkage type other than "externally visible", <tt>dllimport</tt>,
573 or <tt>extern_weak</tt>.</p>
574 <p>Aliases can have only <tt>external</tt>, <tt>internal</tt> and <tt>weak</tt>
578 <!-- ======================================================================= -->
579 <div class="doc_subsection">
580 <a name="callingconv">Calling Conventions</a>
583 <div class="doc_text">
585 <p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
586 and <a href="#i_invoke">invokes</a> can all have an optional calling convention
587 specified for the call. The calling convention of any pair of dynamic
588 caller/callee must match, or the behavior of the program is undefined. The
589 following calling conventions are supported by LLVM, and more may be added in
593 <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>
595 <dd>This calling convention (the default if no other calling convention is
596 specified) matches the target C calling conventions. This calling convention
597 supports varargs function calls and tolerates some mismatch in the declared
598 prototype and implemented declaration of the function (as does normal C).
601 <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
603 <dd>This calling convention attempts to make calls as fast as possible
604 (e.g. by passing things in registers). This calling convention allows the
605 target to use whatever tricks it wants to produce fast code for the target,
606 without having to conform to an externally specified ABI (Application Binary
607 Interface). Implementations of this convention should allow arbitrary
608 <a href="CodeGenerator.html#tailcallopt">tail call optimization</a> to be
609 supported. This calling convention does not support varargs and requires the
610 prototype of all callees to exactly match the prototype of the function
614 <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>
616 <dd>This calling convention attempts to make code in the caller as efficient
617 as possible under the assumption that the call is not commonly executed. As
618 such, these calls often preserve all registers so that the call does not break
619 any live ranges in the caller side. This calling convention does not support
620 varargs and requires the prototype of all callees to exactly match the
621 prototype of the function definition.
624 <dt><b>"<tt>cc <<em>n</em>></tt>" - Numbered convention</b>:</dt>
626 <dd>Any calling convention may be specified by number, allowing
627 target-specific calling conventions to be used. Target specific calling
628 conventions start at 64.
632 <p>More calling conventions can be added/defined on an as-needed basis, to
633 support pascal conventions or any other well-known target-independent
638 <!-- ======================================================================= -->
639 <div class="doc_subsection">
640 <a name="visibility">Visibility Styles</a>
643 <div class="doc_text">
646 All Global Variables and Functions have one of the following visibility styles:
650 <dt><b>"<tt>default</tt>" - Default style</b>:</dt>
652 <dd>On targets that use the ELF object file format, default visibility means
653 that the declaration is visible to other
654 modules and, in shared libraries, means that the declared entity may be
655 overridden. On Darwin, default visibility means that the declaration is
656 visible to other modules. Default visibility corresponds to "external
657 linkage" in the language.
660 <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>
662 <dd>Two declarations of an object with hidden visibility refer to the same
663 object if they are in the same shared object. Usually, hidden visibility
664 indicates that the symbol will not be placed into the dynamic symbol table,
665 so no other module (executable or shared library) can reference it
669 <dt><b>"<tt>protected</tt>" - Protected style</b>:</dt>
671 <dd>On ELF, protected visibility indicates that the symbol will be placed in
672 the dynamic symbol table, but that references within the defining module will
673 bind to the local symbol. That is, the symbol cannot be overridden by another
680 <!-- ======================================================================= -->
681 <div class="doc_subsection">
682 <a name="globalvars">Global Variables</a>
685 <div class="doc_text">
687 <p>Global variables define regions of memory allocated at compilation time
688 instead of run-time. Global variables may optionally be initialized, may have
689 an explicit section to be placed in, and may have an optional explicit alignment
690 specified. A variable may be defined as "thread_local", which means that it
691 will not be shared by threads (each thread will have a separated copy of the
692 variable). A variable may be defined as a global "constant," which indicates
693 that the contents of the variable will <b>never</b> be modified (enabling better
694 optimization, allowing the global data to be placed in the read-only section of
695 an executable, etc). Note that variables that need runtime initialization
696 cannot be marked "constant" as there is a store to the variable.</p>
699 LLVM explicitly allows <em>declarations</em> of global variables to be marked
700 constant, even if the final definition of the global is not. This capability
701 can be used to enable slightly better optimization of the program, but requires
702 the language definition to guarantee that optimizations based on the
703 'constantness' are valid for the translation units that do not include the
707 <p>As SSA values, global variables define pointer values that are in
708 scope (i.e. they dominate) all basic blocks in the program. Global
709 variables always define a pointer to their "content" type because they
710 describe a region of memory, and all memory objects in LLVM are
711 accessed through pointers.</p>
713 <p>A global variable may be declared to reside in a target-specifc numbered
714 address space. For targets that support them, address spaces may affect how
715 optimizations are performed and/or what target instructions are used to access
716 the variable. The default address space is zero. The address space qualifier
717 must precede any other attributes.</p>
719 <p>LLVM allows an explicit section to be specified for globals. If the target
720 supports it, it will emit globals to the section specified.</p>
722 <p>An explicit alignment may be specified for a global. If not present, or if
723 the alignment is set to zero, the alignment of the global is set by the target
724 to whatever it feels convenient. If an explicit alignment is specified, the
725 global is forced to have at least that much alignment. All alignments must be
728 <p>For example, the following defines a global in a numbered address space with
729 an initializer, section, and alignment:</p>
731 <div class="doc_code">
733 @G = constant float 1.0 addrspace(5), section "foo", align 4
740 <!-- ======================================================================= -->
741 <div class="doc_subsection">
742 <a name="functionstructure">Functions</a>
745 <div class="doc_text">
747 <p>LLVM function definitions consist of the "<tt>define</tt>" keyord,
748 an optional <a href="#linkage">linkage type</a>, an optional
749 <a href="#visibility">visibility style</a>, an optional
750 <a href="#callingconv">calling convention</a>, a return type, an optional
751 <a href="#paramattrs">parameter attribute</a> for the return type, a function
752 name, a (possibly empty) argument list (each with optional
753 <a href="#paramattrs">parameter attributes</a>), an optional section, an
754 optional alignment, an optional <a href="#gc">garbage collector name</a>,
755 an optional <a href="#notes">function notes</a>, an
756 opening curly brace, a list of basic blocks, and a closing curly brace.
758 LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
759 optional <a href="#linkage">linkage type</a>, an optional
760 <a href="#visibility">visibility style</a>, an optional
761 <a href="#callingconv">calling convention</a>, a return type, an optional
762 <a href="#paramattrs">parameter attribute</a> for the return type, a function
763 name, a possibly empty list of arguments, an optional alignment, and an optional
764 <a href="#gc">garbage collector name</a>.</p>
766 <p>A function definition contains a list of basic blocks, forming the CFG
767 (Control Flow Graph) for
768 the function. Each basic block may optionally start with a label (giving the
769 basic block a symbol table entry), contains a list of instructions, and ends
770 with a <a href="#terminators">terminator</a> instruction (such as a branch or
771 function return).</p>
773 <p>The first basic block in a function is special in two ways: it is immediately
774 executed on entrance to the function, and it is not allowed to have predecessor
775 basic blocks (i.e. there can not be any branches to the entry block of a
776 function). Because the block can have no predecessors, it also cannot have any
777 <a href="#i_phi">PHI nodes</a>.</p>
779 <p>LLVM allows an explicit section to be specified for functions. If the target
780 supports it, it will emit functions to the section specified.</p>
782 <p>An explicit alignment may be specified for a function. If not present, or if
783 the alignment is set to zero, the alignment of the function is set by the target
784 to whatever it feels convenient. If an explicit alignment is specified, the
785 function is forced to have at least that much alignment. All alignments must be
791 <!-- ======================================================================= -->
792 <div class="doc_subsection">
793 <a name="aliasstructure">Aliases</a>
795 <div class="doc_text">
796 <p>Aliases act as "second name" for the aliasee value (which can be either
797 function, global variable, another alias or bitcast of global value). Aliases
798 may have an optional <a href="#linkage">linkage type</a>, and an
799 optional <a href="#visibility">visibility style</a>.</p>
803 <div class="doc_code">
805 @<Name> = alias [Linkage] [Visibility] <AliaseeTy> @<Aliasee>
813 <!-- ======================================================================= -->
814 <div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
815 <div class="doc_text">
816 <p>The return type and each parameter of a function type may have a set of
817 <i>parameter attributes</i> associated with them. Parameter attributes are
818 used to communicate additional information about the result or parameters of
819 a function. Parameter attributes are considered to be part of the function,
820 not of the function type, so functions with different parameter attributes
821 can have the same function type.</p>
823 <p>Parameter attributes are simple keywords that follow the type specified. If
824 multiple parameter attributes are needed, they are space separated. For
827 <div class="doc_code">
829 declare i32 @printf(i8* noalias , ...) nounwind
830 declare i32 @atoi(i8*) nounwind readonly
834 <p>Note that any attributes for the function result (<tt>nounwind</tt>,
835 <tt>readonly</tt>) come immediately after the argument list.</p>
837 <p>Currently, only the following parameter attributes are defined:</p>
839 <dt><tt>zeroext</tt></dt>
840 <dd>This indicates that the parameter should be zero extended just before
841 a call to this function.</dd>
843 <dt><tt>signext</tt></dt>
844 <dd>This indicates that the parameter should be sign extended just before
845 a call to this function.</dd>
847 <dt><tt>inreg</tt></dt>
848 <dd>This indicates that the parameter should be placed in register (if
849 possible) during assembling function call. Support for this attribute is
852 <dt><tt>byval</tt></dt>
853 <dd>This indicates that the pointer parameter should really be passed by
854 value to the function. The attribute implies that a hidden copy of the
855 pointee is made between the caller and the callee, so the callee is unable
856 to modify the value in the callee. This attribute is only valid on LLVM
857 pointer arguments. It is generally used to pass structs and arrays by
858 value, but is also valid on scalars (even though this is silly).</dd>
860 <dt><tt>sret</tt></dt>
861 <dd>This indicates that the pointer parameter specifies the address of a
862 structure that is the return value of the function in the source program.
863 Loads and stores to the structure are assumed not to trap.
864 May only be applied to the first parameter.</dd>
866 <dt><tt>noalias</tt></dt>
867 <dd>This indicates that the parameter does not alias any global or any other
868 parameter. The caller is responsible for ensuring that this is the case,
869 usually by placing the value in a stack allocation.</dd>
871 <dt><tt>noreturn</tt></dt>
872 <dd>This function attribute indicates that the function never returns. This
873 indicates to LLVM that every call to this function should be treated as if
874 an <tt>unreachable</tt> instruction immediately followed the call.</dd>
876 <dt><tt>nounwind</tt></dt>
877 <dd>This function attribute indicates that no exceptions unwind out of the
878 function. Usually this is because the function makes no use of exceptions,
879 but it may also be that the function catches any exceptions thrown when
882 <dt><tt>nest</tt></dt>
883 <dd>This indicates that the pointer parameter can be excised using the
884 <a href="#int_trampoline">trampoline intrinsics</a>.</dd>
885 <dt><tt>readonly</tt></dt>
886 <dd>This function attribute indicates that the function has no side-effects
887 except for producing a return value or throwing an exception. The value
888 returned must only depend on the function arguments and/or global variables.
889 It may use values obtained by dereferencing pointers.</dd>
890 <dt><tt>readnone</tt></dt>
891 <dd>A <tt>readnone</tt> function has the same restrictions as a <tt>readonly</tt>
892 function, but in addition it is not allowed to dereference any pointer arguments
898 <!-- ======================================================================= -->
899 <div class="doc_subsection">
900 <a name="gc">Garbage Collector Names</a>
903 <div class="doc_text">
904 <p>Each function may specify a garbage collector name, which is simply a
907 <div class="doc_code"><pre
908 >define void @f() gc "name" { ...</pre></div>
910 <p>The compiler declares the supported values of <i>name</i>. Specifying a
911 collector which will cause the compiler to alter its output in order to support
912 the named garbage collection algorithm.</p>
915 <!-- ======================================================================= -->
916 <div class="doc_subsection">
917 <a name="notes">Function Notes</a>
920 <div class="doc_text">
921 <p>The function definition may list function notes which are used by
924 <div class="doc_code">
926 define void @f() notes(inline=Always) { ... }
927 define void @f() notes(inline=Always,opt-size) { ... }
928 define void @f() notes(inline=Never,opt-size) { ... }
929 define void @f() notes(opt-size) { ... }
934 <dt><tt>inline=Always</tt></dt>
935 <dd>This note requests inliner to inline this function irrespective of inlining
936 size threshold for this function.</dd>
938 <dt><tt>inline=Never</tt></dt>
939 <dd>This note requests inliner to never inline this function in any situation.
940 This note may not be used together with <tt>inline=Always</tt> note.</dd>
942 <dt><tt>opt-size</tt></dt>
943 <dd>This note suggests optimization passes and code generator passes to make
944 choices that help reduce code size.</dd>
948 <p>Any notes that are not documented here are considered invalid notes.</p>
951 <!-- ======================================================================= -->
952 <div class="doc_subsection">
953 <a name="moduleasm">Module-Level Inline Assembly</a>
956 <div class="doc_text">
958 Modules may contain "module-level inline asm" blocks, which corresponds to the
959 GCC "file scope inline asm" blocks. These blocks are internally concatenated by
960 LLVM and treated as a single unit, but may be separated in the .ll file if
961 desired. The syntax is very simple:
964 <div class="doc_code">
966 module asm "inline asm code goes here"
967 module asm "more can go here"
971 <p>The strings can contain any character by escaping non-printable characters.
972 The escape sequence used is simply "\xx" where "xx" is the two digit hex code
977 The inline asm code is simply printed to the machine code .s file when
978 assembly code is generated.
982 <!-- ======================================================================= -->
983 <div class="doc_subsection">
984 <a name="datalayout">Data Layout</a>
987 <div class="doc_text">
988 <p>A module may specify a target specific data layout string that specifies how
989 data is to be laid out in memory. The syntax for the data layout is simply:</p>
990 <pre> target datalayout = "<i>layout specification</i>"</pre>
991 <p>The <i>layout specification</i> consists of a list of specifications
992 separated by the minus sign character ('-'). Each specification starts with a
993 letter and may include other information after the letter to define some
994 aspect of the data layout. The specifications accepted are as follows: </p>
997 <dd>Specifies that the target lays out data in big-endian form. That is, the
998 bits with the most significance have the lowest address location.</dd>
1000 <dd>Specifies that the target lays out data in little-endian form. That is,
1001 the bits with the least significance have the lowest address location.</dd>
1002 <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1003 <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and
1004 <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
1005 alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
1007 <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1008 <dd>This specifies the alignment for an integer type of a given bit
1009 <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
1010 <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1011 <dd>This specifies the alignment for a vector type of a given bit
1013 <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1014 <dd>This specifies the alignment for a floating point type of a given bit
1015 <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
1017 <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
1018 <dd>This specifies the alignment for an aggregate type of a given bit
1021 <p>When constructing the data layout for a given target, LLVM starts with a
1022 default set of specifications which are then (possibly) overriden by the
1023 specifications in the <tt>datalayout</tt> keyword. The default specifications
1024 are given in this list:</p>
1026 <li><tt>E</tt> - big endian</li>
1027 <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
1028 <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
1029 <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
1030 <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
1031 <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
1032 <li><tt>i64:32:64</tt> - i64 has ABI alignment of 32-bits but preferred
1033 alignment of 64-bits</li>
1034 <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
1035 <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
1036 <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
1037 <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
1038 <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
1040 <p>When LLVM is determining the alignment for a given type, it uses the
1043 <li>If the type sought is an exact match for one of the specifications, that
1044 specification is used.</li>
1045 <li>If no match is found, and the type sought is an integer type, then the
1046 smallest integer type that is larger than the bitwidth of the sought type is
1047 used. If none of the specifications are larger than the bitwidth then the the
1048 largest integer type is used. For example, given the default specifications
1049 above, the i7 type will use the alignment of i8 (next largest) while both
1050 i65 and i256 will use the alignment of i64 (largest specified).</li>
1051 <li>If no match is found, and the type sought is a vector type, then the
1052 largest vector type that is smaller than the sought vector type will be used
1053 as a fall back. This happens because <128 x double> can be implemented in
1054 terms of 64 <2 x double>, for example.</li>
1058 <!-- *********************************************************************** -->
1059 <div class="doc_section"> <a name="typesystem">Type System</a> </div>
1060 <!-- *********************************************************************** -->
1062 <div class="doc_text">
1064 <p>The LLVM type system is one of the most important features of the
1065 intermediate representation. Being typed enables a number of
1066 optimizations to be performed on the intermediate representation directly,
1067 without having to do
1068 extra analyses on the side before the transformation. A strong type
1069 system makes it easier to read the generated code and enables novel
1070 analyses and transformations that are not feasible to perform on normal
1071 three address code representations.</p>
1075 <!-- ======================================================================= -->
1076 <div class="doc_subsection"> <a name="t_classifications">Type
1077 Classifications</a> </div>
1078 <div class="doc_text">
1079 <p>The types fall into a few useful
1080 classifications:</p>
1082 <table border="1" cellspacing="0" cellpadding="4">
1084 <tr><th>Classification</th><th>Types</th></tr>
1086 <td><a href="#t_integer">integer</a></td>
1087 <td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
1090 <td><a href="#t_floating">floating point</a></td>
1091 <td><tt>float, double, x86_fp80, fp128, ppc_fp128</tt></td>
1094 <td><a name="t_firstclass">first class</a></td>
1095 <td><a href="#t_integer">integer</a>,
1096 <a href="#t_floating">floating point</a>,
1097 <a href="#t_pointer">pointer</a>,
1098 <a href="#t_vector">vector</a>,
1099 <a href="#t_struct">structure</a>,
1100 <a href="#t_array">array</a>,
1101 <a href="#t_label">label</a>.
1105 <td><a href="#t_primitive">primitive</a></td>
1106 <td><a href="#t_label">label</a>,
1107 <a href="#t_void">void</a>,
1108 <a href="#t_floating">floating point</a>.</td>
1111 <td><a href="#t_derived">derived</a></td>
1112 <td><a href="#t_integer">integer</a>,
1113 <a href="#t_array">array</a>,
1114 <a href="#t_function">function</a>,
1115 <a href="#t_pointer">pointer</a>,
1116 <a href="#t_struct">structure</a>,
1117 <a href="#t_pstruct">packed structure</a>,
1118 <a href="#t_vector">vector</a>,
1119 <a href="#t_opaque">opaque</a>.
1124 <p>The <a href="#t_firstclass">first class</a> types are perhaps the
1125 most important. Values of these types are the only ones which can be
1126 produced by instructions, passed as arguments, or used as operands to
1130 <!-- ======================================================================= -->
1131 <div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
1133 <div class="doc_text">
1134 <p>The primitive types are the fundamental building blocks of the LLVM
1139 <!-- _______________________________________________________________________ -->
1140 <div class="doc_subsubsection"> <a name="t_floating">Floating Point Types</a> </div>
1142 <div class="doc_text">
1145 <tr><th>Type</th><th>Description</th></tr>
1146 <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
1147 <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
1148 <tr><td><tt>fp128</tt></td><td>128-bit floating point value (112-bit mantissa)</td></tr>
1149 <tr><td><tt>x86_fp80</tt></td><td>80-bit floating point value (X87)</td></tr>
1150 <tr><td><tt>ppc_fp128</tt></td><td>128-bit floating point value (two 64-bits)</td></tr>
1155 <!-- _______________________________________________________________________ -->
1156 <div class="doc_subsubsection"> <a name="t_void">Void Type</a> </div>
1158 <div class="doc_text">
1160 <p>The void type does not represent any value and has no size.</p>
1169 <!-- _______________________________________________________________________ -->
1170 <div class="doc_subsubsection"> <a name="t_label">Label Type</a> </div>
1172 <div class="doc_text">
1174 <p>The label type represents code labels.</p>
1184 <!-- ======================================================================= -->
1185 <div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>
1187 <div class="doc_text">
1189 <p>The real power in LLVM comes from the derived types in the system.
1190 This is what allows a programmer to represent arrays, functions,
1191 pointers, and other useful types. Note that these derived types may be
1192 recursive: For example, it is possible to have a two dimensional array.</p>
1196 <!-- _______________________________________________________________________ -->
1197 <div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>
1199 <div class="doc_text">
1202 <p>The integer type is a very simple derived type that simply specifies an
1203 arbitrary bit width for the integer type desired. Any bit width from 1 bit to
1204 2^23-1 (about 8 million) can be specified.</p>
1212 <p>The number of bits the integer will occupy is specified by the <tt>N</tt>
1216 <table class="layout">
1219 <td><tt>i1</tt></td>
1220 <td>a single-bit integer.</td>
1222 <td><tt>i32</tt></td>
1223 <td>a 32-bit integer.</td>
1225 <td><tt>i1942652</tt></td>
1226 <td>a really big integer of over 1 million bits.</td>
1232 <!-- _______________________________________________________________________ -->
1233 <div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>
1235 <div class="doc_text">
1239 <p>The array type is a very simple derived type that arranges elements
1240 sequentially in memory. The array type requires a size (number of
1241 elements) and an underlying data type.</p>
1246 [<# elements> x <elementtype>]
1249 <p>The number of elements is a constant integer value; elementtype may
1250 be any type with a size.</p>
1253 <table class="layout">
1255 <td class="left"><tt>[40 x i32]</tt></td>
1256 <td class="left">Array of 40 32-bit integer values.</td>
1259 <td class="left"><tt>[41 x i32]</tt></td>
1260 <td class="left">Array of 41 32-bit integer values.</td>
1263 <td class="left"><tt>[4 x i8]</tt></td>
1264 <td class="left">Array of 4 8-bit integer values.</td>
1267 <p>Here are some examples of multidimensional arrays:</p>
1268 <table class="layout">
1270 <td class="left"><tt>[3 x [4 x i32]]</tt></td>
1271 <td class="left">3x4 array of 32-bit integer values.</td>
1274 <td class="left"><tt>[12 x [10 x float]]</tt></td>
1275 <td class="left">12x10 array of single precision floating point values.</td>
1278 <td class="left"><tt>[2 x [3 x [4 x i16]]]</tt></td>
1279 <td class="left">2x3x4 array of 16-bit integer values.</td>
1283 <p>Note that 'variable sized arrays' can be implemented in LLVM with a zero
1284 length array. Normally, accesses past the end of an array are undefined in
1285 LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
1286 As a special case, however, zero length arrays are recognized to be variable
1287 length. This allows implementation of 'pascal style arrays' with the LLVM
1288 type "{ i32, [0 x float]}", for example.</p>
1292 <!-- _______________________________________________________________________ -->
1293 <div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
1294 <div class="doc_text">
1298 <p>The function type can be thought of as a function signature. It
1299 consists of a return type and a list of formal parameter types. The
1300 return type of a function type is a scalar type, a void type, or a struct type.
1301 If the return type is a struct type then all struct elements must be of first
1302 class types, and the struct must have at least one element.</p>
1307 <returntype list> (<parameter list>)
1310 <p>...where '<tt><parameter list></tt>' is a comma-separated list of type
1311 specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
1312 which indicates that the function takes a variable number of arguments.
1313 Variable argument functions can access their arguments with the <a
1314 href="#int_varargs">variable argument handling intrinsic</a> functions.
1315 '<tt><returntype list></tt>' is a comma-separated list of
1316 <a href="#t_firstclass">first class</a> type specifiers.</p>
1319 <table class="layout">
1321 <td class="left"><tt>i32 (i32)</tt></td>
1322 <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
1324 </tr><tr class="layout">
1325 <td class="left"><tt>float (i16 signext, i32 *) *
1327 <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
1328 an <tt>i16</tt> that should be sign extended and a
1329 <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning
1332 </tr><tr class="layout">
1333 <td class="left"><tt>i32 (i8*, ...)</tt></td>
1334 <td class="left">A vararg function that takes at least one
1335 <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C),
1336 which returns an integer. This is the signature for <tt>printf</tt> in
1339 </tr><tr class="layout">
1340 <td class="left"><tt>{i32, i32} (i32)</tt></td>
1341 <td class="left">A function taking an <tt>i32></tt>, returning two
1342 <tt> i32 </tt> values as an aggregate of type <tt>{ i32, i32 }</tt>
1348 <!-- _______________________________________________________________________ -->
1349 <div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
1350 <div class="doc_text">
1352 <p>The structure type is used to represent a collection of data members
1353 together in memory. The packing of the field types is defined to match
1354 the ABI of the underlying processor. The elements of a structure may
1355 be any type that has a size.</p>
1356 <p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1357 and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1358 field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1361 <pre> { <type list> }<br></pre>
1363 <table class="layout">
1365 <td class="left"><tt>{ i32, i32, i32 }</tt></td>
1366 <td class="left">A triple of three <tt>i32</tt> values</td>
1367 </tr><tr class="layout">
1368 <td class="left"><tt>{ float, i32 (i32) * }</tt></td>
1369 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1370 second element is a <a href="#t_pointer">pointer</a> to a
1371 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1372 an <tt>i32</tt>.</td>
1377 <!-- _______________________________________________________________________ -->
1378 <div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
1380 <div class="doc_text">
1382 <p>The packed structure type is used to represent a collection of data members
1383 together in memory. There is no padding between fields. Further, the alignment
1384 of a packed structure is 1 byte. The elements of a packed structure may
1385 be any type that has a size.</p>
1386 <p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
1387 and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
1388 field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
1391 <pre> < { <type list> } > <br></pre>
1393 <table class="layout">
1395 <td class="left"><tt>< { i32, i32, i32 } ></tt></td>
1396 <td class="left">A triple of three <tt>i32</tt> values</td>
1397 </tr><tr class="layout">
1399 <tt>< { float, i32 (i32)* } ></tt></td>
1400 <td class="left">A pair, where the first element is a <tt>float</tt> and the
1401 second element is a <a href="#t_pointer">pointer</a> to a
1402 <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
1403 an <tt>i32</tt>.</td>
1408 <!-- _______________________________________________________________________ -->
1409 <div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
1410 <div class="doc_text">
1412 <p>As in many languages, the pointer type represents a pointer or
1413 reference to another object, which must live in memory. Pointer types may have
1414 an optional address space attribute defining the target-specific numbered
1415 address space where the pointed-to object resides. The default address space is
1418 <pre> <type> *<br></pre>
1420 <table class="layout">
1422 <td class="left"><tt>[4x i32]*</tt></td>
1423 <td class="left">A <a href="#t_pointer">pointer</a> to <a
1424 href="#t_array">array</a> of four <tt>i32</tt> values.</td>
1427 <td class="left"><tt>i32 (i32 *) *</tt></td>
1428 <td class="left"> A <a href="#t_pointer">pointer</a> to a <a
1429 href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
1433 <td class="left"><tt>i32 addrspace(5)*</tt></td>
1434 <td class="left">A <a href="#t_pointer">pointer</a> to an <tt>i32</tt> value
1435 that resides in address space #5.</td>
1440 <!-- _______________________________________________________________________ -->
1441 <div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
1442 <div class="doc_text">
1446 <p>A vector type is a simple derived type that represents a vector
1447 of elements. Vector types are used when multiple primitive data
1448 are operated in parallel using a single instruction (SIMD).
1449 A vector type requires a size (number of
1450 elements) and an underlying primitive data type. Vectors must have a power
1451 of two length (1, 2, 4, 8, 16 ...). Vector types are
1452 considered <a href="#t_firstclass">first class</a>.</p>
1457 < <# elements> x <elementtype> >
1460 <p>The number of elements is a constant integer value; elementtype may
1461 be any integer or floating point type.</p>
1465 <table class="layout">
1467 <td class="left"><tt><4 x i32></tt></td>
1468 <td class="left">Vector of 4 32-bit integer values.</td>
1471 <td class="left"><tt><8 x float></tt></td>
1472 <td class="left">Vector of 8 32-bit floating-point values.</td>
1475 <td class="left"><tt><2 x i64></tt></td>
1476 <td class="left">Vector of 2 64-bit integer values.</td>
1481 <!-- _______________________________________________________________________ -->
1482 <div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
1483 <div class="doc_text">
1487 <p>Opaque types are used to represent unknown types in the system. This
1488 corresponds (for example) to the C notion of a forward declared structure type.
1489 In LLVM, opaque types can eventually be resolved to any type (not just a
1490 structure type).</p>
1500 <table class="layout">
1502 <td class="left"><tt>opaque</tt></td>
1503 <td class="left">An opaque type.</td>
1509 <!-- *********************************************************************** -->
1510 <div class="doc_section"> <a name="constants">Constants</a> </div>
1511 <!-- *********************************************************************** -->
1513 <div class="doc_text">
1515 <p>LLVM has several different basic types of constants. This section describes
1516 them all and their syntax.</p>
1520 <!-- ======================================================================= -->
1521 <div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>
1523 <div class="doc_text">
1526 <dt><b>Boolean constants</b></dt>
1528 <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
1529 constants of the <tt><a href="#t_primitive">i1</a></tt> type.
1532 <dt><b>Integer constants</b></dt>
1534 <dd>Standard integers (such as '4') are constants of the <a
1535 href="#t_integer">integer</a> type. Negative numbers may be used with
1539 <dt><b>Floating point constants</b></dt>
1541 <dd>Floating point constants use standard decimal notation (e.g. 123.421),
1542 exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
1543 notation (see below). The assembler requires the exact decimal value of
1544 a floating-point constant. For example, the assembler accepts 1.25 but
1545 rejects 1.3 because 1.3 is a repeating decimal in binary. Floating point
1546 constants must have a <a href="#t_floating">floating point</a> type. </dd>
1548 <dt><b>Null pointer constants</b></dt>
1550 <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
1551 and must be of <a href="#t_pointer">pointer type</a>.</dd>
1555 <p>The one non-intuitive notation for constants is the optional hexadecimal form
1556 of floating point constants. For example, the form '<tt>double
1557 0x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
1558 4.5e+15</tt>'. The only time hexadecimal floating point constants are required
1559 (and the only time that they are generated by the disassembler) is when a
1560 floating point constant must be emitted but it cannot be represented as a
1561 decimal floating point number. For example, NaN's, infinities, and other
1562 special values are represented in their IEEE hexadecimal format so that
1563 assembly and disassembly do not cause any bits to change in the constants.</p>
1567 <!-- ======================================================================= -->
1568 <div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
1571 <div class="doc_text">
1572 <p>Aggregate constants arise from aggregation of simple constants
1573 and smaller aggregate constants.</p>
1576 <dt><b>Structure constants</b></dt>
1578 <dd>Structure constants are represented with notation similar to structure
1579 type definitions (a comma separated list of elements, surrounded by braces
1580 (<tt>{}</tt>)). For example: "<tt>{ i32 4, float 17.0, i32* @G }</tt>",
1581 where "<tt>@G</tt>" is declared as "<tt>@G = external global i32</tt>". Structure constants
1582 must have <a href="#t_struct">structure type</a>, and the number and
1583 types of elements must match those specified by the type.
1586 <dt><b>Array constants</b></dt>
1588 <dd>Array constants are represented with notation similar to array type
1589 definitions (a comma separated list of elements, surrounded by square brackets
1590 (<tt>[]</tt>)). For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>". Array
1591 constants must have <a href="#t_array">array type</a>, and the number and
1592 types of elements must match those specified by the type.
1595 <dt><b>Vector constants</b></dt>
1597 <dd>Vector constants are represented with notation similar to vector type
1598 definitions (a comma separated list of elements, surrounded by
1599 less-than/greater-than's (<tt><></tt>)). For example: "<tt>< i32 42,
1600 i32 11, i32 74, i32 100 ></tt>". Vector constants must have <a
1601 href="#t_vector">vector type</a>, and the number and types of elements must
1602 match those specified by the type.
1605 <dt><b>Zero initialization</b></dt>
1607 <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
1608 value to zero of <em>any</em> type, including scalar and aggregate types.
1609 This is often used to avoid having to print large zero initializers (e.g. for
1610 large arrays) and is always exactly equivalent to using explicit zero
1617 <!-- ======================================================================= -->
1618 <div class="doc_subsection">
1619 <a name="globalconstants">Global Variable and Function Addresses</a>
1622 <div class="doc_text">
1624 <p>The addresses of <a href="#globalvars">global variables</a> and <a
1625 href="#functionstructure">functions</a> are always implicitly valid (link-time)
1626 constants. These constants are explicitly referenced when the <a
1627 href="#identifiers">identifier for the global</a> is used and always have <a
1628 href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
1631 <div class="doc_code">
1635 @Z = global [2 x i32*] [ i32* @X, i32* @Y ]
1641 <!-- ======================================================================= -->
1642 <div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
1643 <div class="doc_text">
1644 <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has
1645 no specific value. Undefined values may be of any type and be used anywhere
1646 a constant is permitted.</p>
1648 <p>Undefined values indicate to the compiler that the program is well defined
1649 no matter what value is used, giving the compiler more freedom to optimize.
1653 <!-- ======================================================================= -->
1654 <div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
1657 <div class="doc_text">
1659 <p>Constant expressions are used to allow expressions involving other constants
1660 to be used as constants. Constant expressions may be of any <a
1661 href="#t_firstclass">first class</a> type and may involve any LLVM operation
1662 that does not have side effects (e.g. load and call are not supported). The
1663 following is the syntax for constant expressions:</p>
1666 <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
1667 <dd>Truncate a constant to another type. The bit size of CST must be larger
1668 than the bit size of TYPE. Both types must be integers.</dd>
1670 <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
1671 <dd>Zero extend a constant to another type. The bit size of CST must be
1672 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1674 <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
1675 <dd>Sign extend a constant to another type. The bit size of CST must be
1676 smaller or equal to the bit size of TYPE. Both types must be integers.</dd>
1678 <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
1679 <dd>Truncate a floating point constant to another floating point type. The
1680 size of CST must be larger than the size of TYPE. Both types must be
1681 floating point.</dd>
1683 <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
1684 <dd>Floating point extend a constant to another type. The size of CST must be
1685 smaller or equal to the size of TYPE. Both types must be floating point.</dd>
1687 <dt><b><tt>fptoui ( CST to TYPE )</tt></b></dt>
1688 <dd>Convert a floating point constant to the corresponding unsigned integer
1689 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1690 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1691 of the same number of elements. If the value won't fit in the integer type,
1692 the results are undefined.</dd>
1694 <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
1695 <dd>Convert a floating point constant to the corresponding signed integer
1696 constant. TYPE must be a scalar or vector integer type. CST must be of scalar
1697 or vector floating point type. Both CST and TYPE must be scalars, or vectors
1698 of the same number of elements. If the value won't fit in the integer type,
1699 the results are undefined.</dd>
1701 <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
1702 <dd>Convert an unsigned integer constant to the corresponding floating point
1703 constant. TYPE must be a scalar or vector floating point type. CST must be of
1704 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1705 of the same number of elements. If the value won't fit in the floating point
1706 type, the results are undefined.</dd>
1708 <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
1709 <dd>Convert a signed integer constant to the corresponding floating point
1710 constant. TYPE must be a scalar or vector floating point type. CST must be of
1711 scalar or vector integer type. Both CST and TYPE must be scalars, or vectors
1712 of the same number of elements. If the value won't fit in the floating point
1713 type, the results are undefined.</dd>
1715 <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
1716 <dd>Convert a pointer typed constant to the corresponding integer constant
1717 TYPE must be an integer type. CST must be of pointer type. The CST value is
1718 zero extended, truncated, or unchanged to make it fit in TYPE.</dd>
1720 <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
1721 <dd>Convert a integer constant to a pointer constant. TYPE must be a
1722 pointer type. CST must be of integer type. The CST value is zero extended,
1723 truncated, or unchanged to make it fit in a pointer size. This one is
1724 <i>really</i> dangerous!</dd>
1726 <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
1727 <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
1728 identical (same number of bits). The conversion is done as if the CST value
1729 was stored to memory and read back as TYPE. In other words, no bits change
1730 with this operator, just the type. This can be used for conversion of
1731 vector types to any other type, as long as they have the same bit width. For
1732 pointers it is only valid to cast to another pointer type. It is not valid
1733 to bitcast to or from an aggregate type.
1736 <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>
1738 <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
1739 constants. As with the <a href="#i_getelementptr">getelementptr</a>
1740 instruction, the index list may have zero or more indexes, which are required
1741 to make sense for the type of "CSTPTR".</dd>
1743 <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>
1745 <dd>Perform the <a href="#i_select">select operation</a> on
1748 <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
1749 <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>
1751 <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
1752 <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>
1754 <dt><b><tt>vicmp COND ( VAL1, VAL2 )</tt></b></dt>
1755 <dd>Performs the <a href="#i_vicmp">vicmp operation</a> on constants.</dd>
1757 <dt><b><tt>vfcmp COND ( VAL1, VAL2 )</tt></b></dt>
1758 <dd>Performs the <a href="#i_vfcmp">vfcmp operation</a> on constants.</dd>
1760 <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>
1762 <dd>Perform the <a href="#i_extractelement">extractelement
1763 operation</a> on constants.
1765 <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>
1767 <dd>Perform the <a href="#i_insertelement">insertelement
1768 operation</a> on constants.</dd>
1771 <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
1773 <dd>Perform the <a href="#i_shufflevector">shufflevector
1774 operation</a> on constants.</dd>
1776 <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
1778 <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
1779 be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
1780 binary</a> operations. The constraints on operands are the same as those for
1781 the corresponding instruction (e.g. no bitwise operations on floating point
1782 values are allowed).</dd>
1786 <!-- *********************************************************************** -->
1787 <div class="doc_section"> <a name="othervalues">Other Values</a> </div>
1788 <!-- *********************************************************************** -->
1790 <!-- ======================================================================= -->
1791 <div class="doc_subsection">
1792 <a name="inlineasm">Inline Assembler Expressions</a>
1795 <div class="doc_text">
1798 LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
1799 Module-Level Inline Assembly</a>) through the use of a special value. This
1800 value represents the inline assembler as a string (containing the instructions
1801 to emit), a list of operand constraints (stored as a string), and a flag that
1802 indicates whether or not the inline asm expression has side effects. An example
1803 inline assembler expression is:
1806 <div class="doc_code">
1808 i32 (i32) asm "bswap $0", "=r,r"
1813 Inline assembler expressions may <b>only</b> be used as the callee operand of
1814 a <a href="#i_call"><tt>call</tt> instruction</a>. Thus, typically we have:
1817 <div class="doc_code">
1819 %X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
1824 Inline asms with side effects not visible in the constraint list must be marked
1825 as having side effects. This is done through the use of the
1826 '<tt>sideeffect</tt>' keyword, like so:
1829 <div class="doc_code">
1831 call void asm sideeffect "eieio", ""()
1835 <p>TODO: The format of the asm and constraints string still need to be
1836 documented here. Constraints on what can be done (e.g. duplication, moving, etc
1837 need to be documented).
1842 <!-- *********************************************************************** -->
1843 <div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
1844 <!-- *********************************************************************** -->
1846 <div class="doc_text">
1848 <p>The LLVM instruction set consists of several different
1849 classifications of instructions: <a href="#terminators">terminator
1850 instructions</a>, <a href="#binaryops">binary instructions</a>,
1851 <a href="#bitwiseops">bitwise binary instructions</a>, <a
1852 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
1853 instructions</a>.</p>
1857 <!-- ======================================================================= -->
1858 <div class="doc_subsection"> <a name="terminators">Terminator
1859 Instructions</a> </div>
1861 <div class="doc_text">
1863 <p>As mentioned <a href="#functionstructure">previously</a>, every
1864 basic block in a program ends with a "Terminator" instruction, which
1865 indicates which block should be executed after the current block is
1866 finished. These terminator instructions typically yield a '<tt>void</tt>'
1867 value: they produce control flow, not values (the one exception being
1868 the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
1869 <p>There are six different terminator instructions: the '<a
1870 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
1871 instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
1872 the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
1873 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
1874 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>
1878 <!-- _______________________________________________________________________ -->
1879 <div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
1880 Instruction</a> </div>
1881 <div class="doc_text">
1883 <pre> ret <type> <value> <i>; Return a value from a non-void function</i>
1884 ret void <i>; Return from void function</i>
1885 ret <type> <value>, <type> <value> <i>; Return two values from a non-void function </i>
1890 <p>The '<tt>ret</tt>' instruction is used to return control flow (and a
1891 value) from a function back to the caller.</p>
1892 <p>There are two forms of the '<tt>ret</tt>' instruction: one that
1893 returns value(s) and then causes control flow, and one that just causes
1894 control flow to occur.</p>
1898 <p>The '<tt>ret</tt>' instruction may return zero, one or multiple values.
1899 The type of each return value must be a '<a href="#t_firstclass">first
1900 class</a>' type. Note that a function is not <a href="#wellformed">well
1901 formed</a> if there exists a '<tt>ret</tt>' instruction inside of the
1902 function that returns values that do not match the return type of the
1907 <p>When the '<tt>ret</tt>' instruction is executed, control flow
1908 returns back to the calling function's context. If the caller is a "<a
1909 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
1910 the instruction after the call. If the caller was an "<a
1911 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
1912 at the beginning of the "normal" destination block. If the instruction
1913 returns a value, that value shall set the call or invoke instruction's
1914 return value. If the instruction returns multiple values then these
1915 values can only be accessed through a '<a href="#i_getresult"><tt>getresult</tt>
1916 </a>' instruction.</p>
1921 ret i32 5 <i>; Return an integer value of 5</i>
1922 ret void <i>; Return from a void function</i>
1923 ret i32 4, i8 2 <i>; Return two values 4 and 2 </i>
1926 <!-- _______________________________________________________________________ -->
1927 <div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
1928 <div class="doc_text">
1930 <pre> br i1 <cond>, label <iftrue>, label <iffalse><br> br label <dest> <i>; Unconditional branch</i>
1933 <p>The '<tt>br</tt>' instruction is used to cause control flow to
1934 transfer to a different basic block in the current function. There are
1935 two forms of this instruction, corresponding to a conditional branch
1936 and an unconditional branch.</p>
1938 <p>The conditional branch form of the '<tt>br</tt>' instruction takes a
1939 single '<tt>i1</tt>' value and two '<tt>label</tt>' values. The
1940 unconditional form of the '<tt>br</tt>' instruction takes a single
1941 '<tt>label</tt>' value as a target.</p>
1943 <p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
1944 argument is evaluated. If the value is <tt>true</tt>, control flows
1945 to the '<tt>iftrue</tt>' <tt>label</tt> argument. If "cond" is <tt>false</tt>,
1946 control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
1948 <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
1949 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br> <a href="#i_ret">ret</a> i32 0<br></pre>
1951 <!-- _______________________________________________________________________ -->
1952 <div class="doc_subsubsection">
1953 <a name="i_switch">'<tt>switch</tt>' Instruction</a>
1956 <div class="doc_text">
1960 switch <intty> <value>, label <defaultdest> [ <intty> <val>, label <dest> ... ]
1965 <p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
1966 several different places. It is a generalization of the '<tt>br</tt>'
1967 instruction, allowing a branch to occur to one of many possible
1973 <p>The '<tt>switch</tt>' instruction uses three parameters: an integer
1974 comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
1975 an array of pairs of comparison value constants and '<tt>label</tt>'s. The
1976 table is not allowed to contain duplicate constant entries.</p>
1980 <p>The <tt>switch</tt> instruction specifies a table of values and
1981 destinations. When the '<tt>switch</tt>' instruction is executed, this
1982 table is searched for the given value. If the value is found, control flow is
1983 transfered to the corresponding destination; otherwise, control flow is
1984 transfered to the default destination.</p>
1986 <h5>Implementation:</h5>
1988 <p>Depending on properties of the target machine and the particular
1989 <tt>switch</tt> instruction, this instruction may be code generated in different
1990 ways. For example, it could be generated as a series of chained conditional
1991 branches or with a lookup table.</p>
1996 <i>; Emulate a conditional br instruction</i>
1997 %Val = <a href="#i_zext">zext</a> i1 %value to i32
1998 switch i32 %Val, label %truedest [i32 0, label %falsedest ]
2000 <i>; Emulate an unconditional br instruction</i>
2001 switch i32 0, label %dest [ ]
2003 <i>; Implement a jump table:</i>
2004 switch i32 %val, label %otherwise [ i32 0, label %onzero
2006 i32 2, label %ontwo ]
2010 <!-- _______________________________________________________________________ -->
2011 <div class="doc_subsubsection">
2012 <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
2015 <div class="doc_text">
2020 <result> = invoke [<a href="#callingconv">cconv</a>] <ptr to function ty> <function ptr val>(<function args>)
2021 to label <normal label> unwind label <exception label>
2026 <p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
2027 function, with the possibility of control flow transfer to either the
2028 '<tt>normal</tt>' label or the
2029 '<tt>exception</tt>' label. If the callee function returns with the
2030 "<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
2031 "normal" label. If the callee (or any indirect callees) returns with the "<a
2032 href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
2033 continued at the dynamically nearest "exception" label. If the callee function
2034 returns multiple values then individual return values are only accessible through
2035 a '<tt><a href="#i_getresult">getresult</a></tt>' instruction.</p>
2039 <p>This instruction requires several arguments:</p>
2043 The optional "cconv" marker indicates which <a href="#callingconv">calling
2044 convention</a> the call should use. If none is specified, the call defaults
2045 to using C calling conventions.
2047 <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
2048 function value being invoked. In most cases, this is a direct function
2049 invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
2050 an arbitrary pointer to function value.
2053 <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
2054 function to be invoked. </li>
2056 <li>'<tt>function args</tt>': argument list whose types match the function
2057 signature argument types. If the function signature indicates the function
2058 accepts a variable number of arguments, the extra arguments can be
2061 <li>'<tt>normal label</tt>': the label reached when the called function
2062 executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>
2064 <li>'<tt>exception label</tt>': the label reached when a callee returns with
2065 the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>
2071 <p>This instruction is designed to operate as a standard '<tt><a
2072 href="#i_call">call</a></tt>' instruction in most regards. The primary
2073 difference is that it establishes an association with a label, which is used by
2074 the runtime library to unwind the stack.</p>
2076 <p>This instruction is used in languages with destructors to ensure that proper
2077 cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
2078 exception. Additionally, this is important for implementation of
2079 '<tt>catch</tt>' clauses in high-level languages that support them.</p>
2083 %retval = invoke i32 @Test(i32 15) to label %Continue
2084 unwind label %TestCleanup <i>; {i32}:retval set</i>
2085 %retval = invoke <a href="#callingconv">coldcc</a> i32 %Testfnptr(i32 15) to label %Continue
2086 unwind label %TestCleanup <i>; {i32}:retval set</i>
2091 <!-- _______________________________________________________________________ -->
2093 <div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
2094 Instruction</a> </div>
2096 <div class="doc_text">
2105 <p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
2106 at the first callee in the dynamic call stack which used an <a
2107 href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call. This is
2108 primarily used to implement exception handling.</p>
2112 <p>The '<tt>unwind</tt>' instruction causes execution of the current function to
2113 immediately halt. The dynamic call stack is then searched for the first <a
2114 href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack. Once found,
2115 execution continues at the "exceptional" destination block specified by the
2116 <tt>invoke</tt> instruction. If there is no <tt>invoke</tt> instruction in the
2117 dynamic call chain, undefined behavior results.</p>
2120 <!-- _______________________________________________________________________ -->
2122 <div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
2123 Instruction</a> </div>
2125 <div class="doc_text">
2134 <p>The '<tt>unreachable</tt>' instruction has no defined semantics. This
2135 instruction is used to inform the optimizer that a particular portion of the
2136 code is not reachable. This can be used to indicate that the code after a
2137 no-return function cannot be reached, and other facts.</p>
2141 <p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
2146 <!-- ======================================================================= -->
2147 <div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
2148 <div class="doc_text">
2149 <p>Binary operators are used to do most of the computation in a
2150 program. They require two operands of the same type, execute an operation on them, and
2151 produce a single value. The operands might represent
2152 multiple data, as is the case with the <a href="#t_vector">vector</a> data type.
2153 The result value has the same type as its operands.</p>
2154 <p>There are several different binary operators:</p>
2156 <!-- _______________________________________________________________________ -->
2157 <div class="doc_subsubsection">
2158 <a name="i_add">'<tt>add</tt>' Instruction</a>
2161 <div class="doc_text">
2166 <result> = add <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2171 <p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
2175 <p>The two arguments to the '<tt>add</tt>' instruction must be <a
2176 href="#t_integer">integer</a>, <a href="#t_floating">floating point</a>, or
2177 <a href="#t_vector">vector</a> values. Both arguments must have identical
2182 <p>The value produced is the integer or floating point sum of the two
2185 <p>If an integer sum has unsigned overflow, the result returned is the
2186 mathematical result modulo 2<sup>n</sup>, where n is the bit width of
2189 <p>Because LLVM integers use a two's complement representation, this
2190 instruction is appropriate for both signed and unsigned integers.</p>
2195 <result> = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
2198 <!-- _______________________________________________________________________ -->
2199 <div class="doc_subsubsection">
2200 <a name="i_sub">'<tt>sub</tt>' Instruction</a>
2203 <div class="doc_text">
2208 <result> = sub <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2213 <p>The '<tt>sub</tt>' instruction returns the difference of its two
2216 <p>Note that the '<tt>sub</tt>' instruction is used to represent the
2217 '<tt>neg</tt>' instruction present in most other intermediate
2218 representations.</p>
2222 <p>The two arguments to the '<tt>sub</tt>' instruction must be <a
2223 href="#t_integer">integer</a>, <a href="#t_floating">floating point</a>,
2224 or <a href="#t_vector">vector</a> values. Both arguments must have identical
2229 <p>The value produced is the integer or floating point difference of
2230 the two operands.</p>
2232 <p>If an integer difference has unsigned overflow, the result returned is the
2233 mathematical result modulo 2<sup>n</sup>, where n is the bit width of
2236 <p>Because LLVM integers use a two's complement representation, this
2237 instruction is appropriate for both signed and unsigned integers.</p>
2241 <result> = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
2242 <result> = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
2246 <!-- _______________________________________________________________________ -->
2247 <div class="doc_subsubsection">
2248 <a name="i_mul">'<tt>mul</tt>' Instruction</a>
2251 <div class="doc_text">
2254 <pre> <result> = mul <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2257 <p>The '<tt>mul</tt>' instruction returns the product of its two
2262 <p>The two arguments to the '<tt>mul</tt>' instruction must be <a
2263 href="#t_integer">integer</a>, <a href="#t_floating">floating point</a>,
2264 or <a href="#t_vector">vector</a> values. Both arguments must have identical
2269 <p>The value produced is the integer or floating point product of the
2272 <p>If the result of an integer multiplication has unsigned overflow,
2273 the result returned is the mathematical result modulo
2274 2<sup>n</sup>, where n is the bit width of the result.</p>
2275 <p>Because LLVM integers use a two's complement representation, and the
2276 result is the same width as the operands, this instruction returns the
2277 correct result for both signed and unsigned integers. If a full product
2278 (e.g. <tt>i32</tt>x<tt>i32</tt>-><tt>i64</tt>) is needed, the operands
2279 should be sign-extended or zero-extended as appropriate to the
2280 width of the full product.</p>
2282 <pre> <result> = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
2286 <!-- _______________________________________________________________________ -->
2287 <div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
2289 <div class="doc_text">
2291 <pre> <result> = udiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2294 <p>The '<tt>udiv</tt>' instruction returns the quotient of its two
2299 <p>The two arguments to the '<tt>udiv</tt>' instruction must be
2300 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2301 values. Both arguments must have identical types.</p>
2305 <p>The value produced is the unsigned integer quotient of the two operands.</p>
2306 <p>Note that unsigned integer division and signed integer division are distinct
2307 operations; for signed integer division, use '<tt>sdiv</tt>'.</p>
2308 <p>Division by zero leads to undefined behavior.</p>
2310 <pre> <result> = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2313 <!-- _______________________________________________________________________ -->
2314 <div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
2316 <div class="doc_text">
2319 <result> = sdiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2324 <p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
2329 <p>The two arguments to the '<tt>sdiv</tt>' instruction must be
2330 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2331 values. Both arguments must have identical types.</p>
2334 <p>The value produced is the signed integer quotient of the two operands rounded towards zero.</p>
2335 <p>Note that signed integer division and unsigned integer division are distinct
2336 operations; for unsigned integer division, use '<tt>udiv</tt>'.</p>
2337 <p>Division by zero leads to undefined behavior. Overflow also leads to
2338 undefined behavior; this is a rare case, but can occur, for example,
2339 by doing a 32-bit division of -2147483648 by -1.</p>
2341 <pre> <result> = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
2344 <!-- _______________________________________________________________________ -->
2345 <div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
2346 Instruction</a> </div>
2347 <div class="doc_text">
2350 <result> = fdiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2354 <p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
2359 <p>The two arguments to the '<tt>fdiv</tt>' instruction must be
2360 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a>
2361 of floating point values. Both arguments must have identical types.</p>
2365 <p>The value produced is the floating point quotient of the two operands.</p>
2370 <result> = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
2374 <!-- _______________________________________________________________________ -->
2375 <div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
2377 <div class="doc_text">
2379 <pre> <result> = urem <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2382 <p>The '<tt>urem</tt>' instruction returns the remainder from the
2383 unsigned division of its two arguments.</p>
2385 <p>The two arguments to the '<tt>urem</tt>' instruction must be
2386 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2387 values. Both arguments must have identical types.</p>
2389 <p>This instruction returns the unsigned integer <i>remainder</i> of a division.
2390 This instruction always performs an unsigned division to get the remainder.</p>
2391 <p>Note that unsigned integer remainder and signed integer remainder are
2392 distinct operations; for signed integer remainder, use '<tt>srem</tt>'.</p>
2393 <p>Taking the remainder of a division by zero leads to undefined behavior.</p>
2395 <pre> <result> = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2399 <!-- _______________________________________________________________________ -->
2400 <div class="doc_subsubsection">
2401 <a name="i_srem">'<tt>srem</tt>' Instruction</a>
2404 <div class="doc_text">
2409 <result> = srem <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2414 <p>The '<tt>srem</tt>' instruction returns the remainder from the
2415 signed division of its two operands. This instruction can also take
2416 <a href="#t_vector">vector</a> versions of the values in which case
2417 the elements must be integers.</p>
2421 <p>The two arguments to the '<tt>srem</tt>' instruction must be
2422 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2423 values. Both arguments must have identical types.</p>
2427 <p>This instruction returns the <i>remainder</i> of a division (where the result
2428 has the same sign as the dividend, <tt>op1</tt>), not the <i>modulo</i>
2429 operator (where the result has the same sign as the divisor, <tt>op2</tt>) of
2430 a value. For more information about the difference, see <a
2431 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
2432 Math Forum</a>. For a table of how this is implemented in various languages,
2433 please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
2434 Wikipedia: modulo operation</a>.</p>
2435 <p>Note that signed integer remainder and unsigned integer remainder are
2436 distinct operations; for unsigned integer remainder, use '<tt>urem</tt>'.</p>
2437 <p>Taking the remainder of a division by zero leads to undefined behavior.
2438 Overflow also leads to undefined behavior; this is a rare case, but can occur,
2439 for example, by taking the remainder of a 32-bit division of -2147483648 by -1.
2440 (The remainder doesn't actually overflow, but this rule lets srem be
2441 implemented using instructions that return both the result of the division
2442 and the remainder.)</p>
2444 <pre> <result> = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
2448 <!-- _______________________________________________________________________ -->
2449 <div class="doc_subsubsection">
2450 <a name="i_frem">'<tt>frem</tt>' Instruction</a> </div>
2452 <div class="doc_text">
2455 <pre> <result> = frem <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2458 <p>The '<tt>frem</tt>' instruction returns the remainder from the
2459 division of its two operands.</p>
2461 <p>The two arguments to the '<tt>frem</tt>' instruction must be
2462 <a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a>
2463 of floating point values. Both arguments must have identical types.</p>
2467 <p>This instruction returns the <i>remainder</i> of a division.
2468 The remainder has the same sign as the dividend.</p>
2473 <result> = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
2477 <!-- ======================================================================= -->
2478 <div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
2479 Operations</a> </div>
2480 <div class="doc_text">
2481 <p>Bitwise binary operators are used to do various forms of
2482 bit-twiddling in a program. They are generally very efficient
2483 instructions and can commonly be strength reduced from other
2484 instructions. They require two operands of the same type, execute an operation on them,
2485 and produce a single value. The resulting value is the same type as its operands.</p>
2488 <!-- _______________________________________________________________________ -->
2489 <div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
2490 Instruction</a> </div>
2491 <div class="doc_text">
2493 <pre> <result> = shl <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2498 <p>The '<tt>shl</tt>' instruction returns the first operand shifted to
2499 the left a specified number of bits.</p>
2503 <p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
2504 href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2505 type. '<tt>op2</tt>' is treated as an unsigned value.</p>
2509 <p>The value produced is <tt>op1</tt> * 2<sup><tt>op2</tt></sup> mod 2<sup>n</sup>,
2510 where n is the width of the result. If <tt>op2</tt> is (statically or dynamically) negative or
2511 equal to or larger than the number of bits in <tt>op1</tt>, the result is undefined.</p>
2513 <h5>Example:</h5><pre>
2514 <result> = shl i32 4, %var <i>; yields {i32}: 4 << %var</i>
2515 <result> = shl i32 4, 2 <i>; yields {i32}: 16</i>
2516 <result> = shl i32 1, 10 <i>; yields {i32}: 1024</i>
2517 <result> = shl i32 1, 32 <i>; undefined</i>
2520 <!-- _______________________________________________________________________ -->
2521 <div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
2522 Instruction</a> </div>
2523 <div class="doc_text">
2525 <pre> <result> = lshr <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2529 <p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first
2530 operand shifted to the right a specified number of bits with zero fill.</p>
2533 <p>Both arguments to the '<tt>lshr</tt>' instruction must be the same
2534 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2535 type. '<tt>op2</tt>' is treated as an unsigned value.</p>
2539 <p>This instruction always performs a logical shift right operation. The most
2540 significant bits of the result will be filled with zero bits after the
2541 shift. If <tt>op2</tt> is (statically or dynamically) equal to or larger than
2542 the number of bits in <tt>op1</tt>, the result is undefined.</p>
2546 <result> = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
2547 <result> = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
2548 <result> = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
2549 <result> = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
2550 <result> = lshr i32 1, 32 <i>; undefined</i>
2554 <!-- _______________________________________________________________________ -->
2555 <div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
2556 Instruction</a> </div>
2557 <div class="doc_text">
2560 <pre> <result> = ashr <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2564 <p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first
2565 operand shifted to the right a specified number of bits with sign extension.</p>
2568 <p>Both arguments to the '<tt>ashr</tt>' instruction must be the same
2569 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2570 type. '<tt>op2</tt>' is treated as an unsigned value.</p>
2573 <p>This instruction always performs an arithmetic shift right operation,
2574 The most significant bits of the result will be filled with the sign bit
2575 of <tt>op1</tt>. If <tt>op2</tt> is (statically or dynamically) equal to or
2576 larger than the number of bits in <tt>op1</tt>, the result is undefined.
2581 <result> = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
2582 <result> = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
2583 <result> = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
2584 <result> = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
2585 <result> = ashr i32 1, 32 <i>; undefined</i>
2589 <!-- _______________________________________________________________________ -->
2590 <div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
2591 Instruction</a> </div>
2593 <div class="doc_text">
2598 <result> = and <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2603 <p>The '<tt>and</tt>' instruction returns the bitwise logical and of
2604 its two operands.</p>
2608 <p>The two arguments to the '<tt>and</tt>' instruction must be
2609 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2610 values. Both arguments must have identical types.</p>
2613 <p>The truth table used for the '<tt>and</tt>' instruction is:</p>
2616 <table border="1" cellspacing="0" cellpadding="4">
2648 <result> = and i32 4, %var <i>; yields {i32}:result = 4 & %var</i>
2649 <result> = and i32 15, 40 <i>; yields {i32}:result = 8</i>
2650 <result> = and i32 4, 8 <i>; yields {i32}:result = 0</i>
2653 <!-- _______________________________________________________________________ -->
2654 <div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
2655 <div class="doc_text">
2657 <pre> <result> = or <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2660 <p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
2661 or of its two operands.</p>
2664 <p>The two arguments to the '<tt>or</tt>' instruction must be
2665 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2666 values. Both arguments must have identical types.</p>
2668 <p>The truth table used for the '<tt>or</tt>' instruction is:</p>
2671 <table border="1" cellspacing="0" cellpadding="4">
2702 <pre> <result> = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
2703 <result> = or i32 15, 40 <i>; yields {i32}:result = 47</i>
2704 <result> = or i32 4, 8 <i>; yields {i32}:result = 12</i>
2707 <!-- _______________________________________________________________________ -->
2708 <div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
2709 Instruction</a> </div>
2710 <div class="doc_text">
2712 <pre> <result> = xor <ty> <op1>, <op2> <i>; yields {ty}:result</i>
2715 <p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
2716 or of its two operands. The <tt>xor</tt> is used to implement the
2717 "one's complement" operation, which is the "~" operator in C.</p>
2719 <p>The two arguments to the '<tt>xor</tt>' instruction must be
2720 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
2721 values. Both arguments must have identical types.</p>
2725 <p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
2728 <table border="1" cellspacing="0" cellpadding="4">
2760 <pre> <result> = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
2761 <result> = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
2762 <result> = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
2763 <result> = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
2767 <!-- ======================================================================= -->
2768 <div class="doc_subsection">
2769 <a name="vectorops">Vector Operations</a>
2772 <div class="doc_text">
2774 <p>LLVM supports several instructions to represent vector operations in a
2775 target-independent manner. These instructions cover the element-access and
2776 vector-specific operations needed to process vectors effectively. While LLVM
2777 does directly support these vector operations, many sophisticated algorithms
2778 will want to use target-specific intrinsics to take full advantage of a specific
2783 <!-- _______________________________________________________________________ -->
2784 <div class="doc_subsubsection">
2785 <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
2788 <div class="doc_text">
2793 <result> = extractelement <n x <ty>> <val>, i32 <idx> <i>; yields <ty></i>
2799 The '<tt>extractelement</tt>' instruction extracts a single scalar
2800 element from a vector at a specified index.
2807 The first operand of an '<tt>extractelement</tt>' instruction is a
2808 value of <a href="#t_vector">vector</a> type. The second operand is
2809 an index indicating the position from which to extract the element.
2810 The index may be a variable.</p>
2815 The result is a scalar of the same type as the element type of
2816 <tt>val</tt>. Its value is the value at position <tt>idx</tt> of
2817 <tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
2818 results are undefined.
2824 %result = extractelement <4 x i32> %vec, i32 0 <i>; yields i32</i>
2829 <!-- _______________________________________________________________________ -->
2830 <div class="doc_subsubsection">
2831 <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
2834 <div class="doc_text">
2839 <result> = insertelement <n x <ty>> <val>, <ty> <elt>, i32 <idx> <i>; yields <n x <ty>></i>
2845 The '<tt>insertelement</tt>' instruction inserts a scalar
2846 element into a vector at a specified index.
2853 The first operand of an '<tt>insertelement</tt>' instruction is a
2854 value of <a href="#t_vector">vector</a> type. The second operand is a
2855 scalar value whose type must equal the element type of the first
2856 operand. The third operand is an index indicating the position at
2857 which to insert the value. The index may be a variable.</p>
2862 The result is a vector of the same type as <tt>val</tt>. Its
2863 element values are those of <tt>val</tt> except at position
2864 <tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
2865 exceeds the length of <tt>val</tt>, the results are undefined.
2871 %result = insertelement <4 x i32> %vec, i32 1, i32 0 <i>; yields <4 x i32></i>
2875 <!-- _______________________________________________________________________ -->
2876 <div class="doc_subsubsection">
2877 <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
2880 <div class="doc_text">
2885 <result> = shufflevector <n x <ty>> <v1>, <n x <ty>> <v2>, <n x i32> <mask> <i>; yields <n x <ty>></i>
2891 The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
2892 from two input vectors, returning a vector of the same type.
2898 The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
2899 with types that match each other and types that match the result of the
2900 instruction. The third argument is a shuffle mask, which has the same number
2901 of elements as the other vector type, but whose element type is always 'i32'.
2905 The shuffle mask operand is required to be a constant vector with either
2906 constant integer or undef values.
2912 The elements of the two input vectors are numbered from left to right across
2913 both of the vectors. The shuffle mask operand specifies, for each element of
2914 the result vector, which element of the two input registers the result element
2915 gets. The element selector may be undef (meaning "don't care") and the second
2916 operand may be undef if performing a shuffle from only one vector.
2922 %result = shufflevector <4 x i32> %v1, <4 x i32> %v2,
2923 <4 x i32> <i32 0, i32 4, i32 1, i32 5> <i>; yields <4 x i32></i>
2924 %result = shufflevector <4 x i32> %v1, <4 x i32> undef,
2925 <4 x i32> <i32 0, i32 1, i32 2, i32 3> <i>; yields <4 x i32></i> - Identity shuffle.
2930 <!-- ======================================================================= -->
2931 <div class="doc_subsection">
2932 <a name="aggregateops">Aggregate Operations</a>
2935 <div class="doc_text">
2937 <p>LLVM supports several instructions for working with aggregate values.
2942 <!-- _______________________________________________________________________ -->
2943 <div class="doc_subsubsection">
2944 <a name="i_extractvalue">'<tt>extractvalue</tt>' Instruction</a>
2947 <div class="doc_text">
2952 <result> = extractvalue <aggregate type> <val>, <idx>{, <idx>}*
2958 The '<tt>extractvalue</tt>' instruction extracts the value of a struct field
2959 or array element from an aggregate value.
2966 The first operand of an '<tt>extractvalue</tt>' instruction is a
2967 value of <a href="#t_struct">struct</a> or <a href="#t_array">array</a>
2968 type. The operands are constant indices to specify which value to extract
2969 in a similar manner as indices in a
2970 '<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.
2976 The result is the value at the position in the aggregate specified by
2983 %result = extractvalue {i32, float} %agg, 0 <i>; yields i32</i>
2988 <!-- _______________________________________________________________________ -->
2989 <div class="doc_subsubsection">
2990 <a name="i_insertvalue">'<tt>insertvalue</tt>' Instruction</a>
2993 <div class="doc_text">
2998 <result> = insertvalue <aggregate type> <val>, <ty> <val>, <idx> <i>; yields <n x <ty>></i>
3004 The '<tt>insertvalue</tt>' instruction inserts a value
3005 into a struct field or array element in an aggregate.
3012 The first operand of an '<tt>insertvalue</tt>' instruction is a
3013 value of <a href="#t_struct">struct</a> or <a href="#t_array">array</a> type.
3014 The second operand is a first-class value to insert.
3015 The following operands are constant indices
3016 indicating the position at which to insert the value in a similar manner as
3018 '<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.
3019 The value to insert must have the same type as the value identified
3025 The result is an aggregate of the same type as <tt>val</tt>. Its
3026 value is that of <tt>val</tt> except that the value at the position
3027 specified by the indices is that of <tt>elt</tt>.
3033 %result = insertvalue {i32, float} %agg, i32 1, 0 <i>; yields {i32, float}</i>
3038 <!-- ======================================================================= -->
3039 <div class="doc_subsection">
3040 <a name="memoryops">Memory Access and Addressing Operations</a>
3043 <div class="doc_text">
3045 <p>A key design point of an SSA-based representation is how it
3046 represents memory. In LLVM, no memory locations are in SSA form, which
3047 makes things very simple. This section describes how to read, write,
3048 allocate, and free memory in LLVM.</p>
3052 <!-- _______________________________________________________________________ -->
3053 <div class="doc_subsubsection">
3054 <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
3057 <div class="doc_text">
3062 <result> = malloc <type>[, i32 <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
3067 <p>The '<tt>malloc</tt>' instruction allocates memory from the system
3068 heap and returns a pointer to it. The object is always allocated in the generic
3069 address space (address space zero).</p>
3073 <p>The '<tt>malloc</tt>' instruction allocates
3074 <tt>sizeof(<type>)*NumElements</tt>
3075 bytes of memory from the operating system and returns a pointer of the
3076 appropriate type to the program. If "NumElements" is specified, it is the
3077 number of elements allocated, otherwise "NumElements" is defaulted to be one.
3078 If a constant alignment is specified, the value result of the allocation is guaranteed to
3079 be aligned to at least that boundary. If not specified, or if zero, the target can
3080 choose to align the allocation on any convenient boundary.</p>
3082 <p>'<tt>type</tt>' must be a sized type.</p>
3086 <p>Memory is allocated using the system "<tt>malloc</tt>" function, and
3087 a pointer is returned. The result of a zero byte allocattion is undefined. The
3088 result is null if there is insufficient memory available.</p>
3093 %array = malloc [4 x i8 ] <i>; yields {[%4 x i8]*}:array</i>
3095 %size = <a href="#i_add">add</a> i32 2, 2 <i>; yields {i32}:size = i32 4</i>
3096 %array1 = malloc i8, i32 4 <i>; yields {i8*}:array1</i>
3097 %array2 = malloc [12 x i8], i32 %size <i>; yields {[12 x i8]*}:array2</i>
3098 %array3 = malloc i32, i32 4, align 1024 <i>; yields {i32*}:array3</i>
3099 %array4 = malloc i32, align 1024 <i>; yields {i32*}:array4</i>
3103 <!-- _______________________________________________________________________ -->
3104 <div class="doc_subsubsection">
3105 <a name="i_free">'<tt>free</tt>' Instruction</a>
3108 <div class="doc_text">
3113 free <type> <value> <i>; yields {void}</i>
3118 <p>The '<tt>free</tt>' instruction returns memory back to the unused
3119 memory heap to be reallocated in the future.</p>
3123 <p>'<tt>value</tt>' shall be a pointer value that points to a value
3124 that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
3129 <p>Access to the memory pointed to by the pointer is no longer defined
3130 after this instruction executes. If the pointer is null, the operation
3136 %array = <a href="#i_malloc">malloc</a> [4 x i8] <i>; yields {[4 x i8]*}:array</i>
3137 free [4 x i8]* %array
3141 <!-- _______________________________________________________________________ -->
3142 <div class="doc_subsubsection">
3143 <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
3146 <div class="doc_text">
3151 <result> = alloca <type>[, i32 <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
3156 <p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
3157 currently executing function, to be automatically released when this function
3158 returns to its caller. The object is always allocated in the generic address
3159 space (address space zero).</p>
3163 <p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(<type>)*NumElements</tt>
3164 bytes of memory on the runtime stack, returning a pointer of the
3165 appropriate type to the program. If "NumElements" is specified, it is the
3166 number of elements allocated, otherwise "NumElements" is defaulted to be one.
3167 If a constant alignment is specified, the value result of the allocation is guaranteed
3168 to be aligned to at least that boundary. If not specified, or if zero, the target
3169 can choose to align the allocation on any convenient boundary.</p>
3171 <p>'<tt>type</tt>' may be any sized type.</p>
3175 <p>Memory is allocated; a pointer is returned. The operation is undefiend if
3176 there is insufficient stack space for the allocation. '<tt>alloca</tt>'d
3177 memory is automatically released when the function returns. The '<tt>alloca</tt>'
3178 instruction is commonly used to represent automatic variables that must
3179 have an address available. When the function returns (either with the <tt><a
3180 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
3181 instructions), the memory is reclaimed. Allocating zero bytes
3182 is legal, but the result is undefined.</p>
3187 %ptr = alloca i32 <i>; yields {i32*}:ptr</i>
3188 %ptr = alloca i32, i32 4 <i>; yields {i32*}:ptr</i>
3189 %ptr = alloca i32, i32 4, align 1024 <i>; yields {i32*}:ptr</i>
3190 %ptr = alloca i32, align 1024 <i>; yields {i32*}:ptr</i>
3194 <!-- _______________________________________________________________________ -->
3195 <div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
3196 Instruction</a> </div>
3197 <div class="doc_text">
3199 <pre> <result> = load <ty>* <pointer>[, align <alignment>]<br> <result> = volatile load <ty>* <pointer>[, align <alignment>]<br></pre>
3201 <p>The '<tt>load</tt>' instruction is used to read from memory.</p>
3203 <p>The argument to the '<tt>load</tt>' instruction specifies the memory
3204 address from which to load. The pointer must point to a <a
3205 href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
3206 marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
3207 the number or order of execution of this <tt>load</tt> with other
3208 volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
3211 The optional constant "align" argument specifies the alignment of the operation
3212 (that is, the alignment of the memory address). A value of 0 or an
3213 omitted "align" argument means that the operation has the preferential
3214 alignment for the target. It is the responsibility of the code emitter
3215 to ensure that the alignment information is correct. Overestimating
3216 the alignment results in an undefined behavior. Underestimating the
3217 alignment may produce less efficient code. An alignment of 1 is always
3221 <p>The location of memory pointed to is loaded.</p>
3223 <pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
3225 href="#i_store">store</a> i32 3, i32* %ptr <i>; yields {void}</i>
3226 %val = load i32* %ptr <i>; yields {i32}:val = i32 3</i>
3229 <!-- _______________________________________________________________________ -->
3230 <div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
3231 Instruction</a> </div>
3232 <div class="doc_text">
3234 <pre> store <ty> <value>, <ty>* <pointer>[, align <alignment>] <i>; yields {void}</i>
3235 volatile store <ty> <value>, <ty>* <pointer>[, align <alignment>] <i>; yields {void}</i>
3238 <p>The '<tt>store</tt>' instruction is used to write to memory.</p>
3240 <p>There are two arguments to the '<tt>store</tt>' instruction: a value
3241 to store and an address at which to store it. The type of the '<tt><pointer></tt>'
3242 operand must be a pointer to the <a href="#t_firstclass">first class</a> type
3243 of the '<tt><value></tt>'
3244 operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
3245 optimizer is not allowed to modify the number or order of execution of
3246 this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
3247 href="#i_store">store</a></tt> instructions.</p>
3249 The optional constant "align" argument specifies the alignment of the operation
3250 (that is, the alignment of the memory address). A value of 0 or an
3251 omitted "align" argument means that the operation has the preferential
3252 alignment for the target. It is the responsibility of the code emitter
3253 to ensure that the alignment information is correct. Overestimating
3254 the alignment results in an undefined behavior. Underestimating the
3255 alignment may produce less efficient code. An alignment of 1 is always
3259 <p>The contents of memory are updated to contain '<tt><value></tt>'
3260 at the location specified by the '<tt><pointer></tt>' operand.</p>
3262 <pre> %ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
3263 store i32 3, i32* %ptr <i>; yields {void}</i>
3264 %val = <a href="#i_load">load</a> i32* %ptr <i>; yields {i32}:val = i32 3</i>
3268 <!-- _______________________________________________________________________ -->
3269 <div class="doc_subsubsection">
3270 <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
3273 <div class="doc_text">
3276 <result> = getelementptr <ty>* <ptrval>{, <ty> <idx>}*
3282 The '<tt>getelementptr</tt>' instruction is used to get the address of a
3283 subelement of an aggregate data structure.</p>
3287 <p>This instruction takes a list of integer operands that indicate what
3288 elements of the aggregate object to index to. The actual types of the arguments
3289 provided depend on the type of the first pointer argument. The
3290 '<tt>getelementptr</tt>' instruction is used to index down through the type
3291 levels of a structure or to a specific index in an array. When indexing into a
3292 structure, only <tt>i32</tt> integer constants are allowed. When indexing
3293 into an array or pointer, only integers of 32 or 64 bits are allowed; 32-bit
3294 values will be sign extended to 64-bits if required.</p>
3296 <p>For example, let's consider a C code fragment and how it gets
3297 compiled to LLVM:</p>
3299 <div class="doc_code">
3312 int *foo(struct ST *s) {
3313 return &s[1].Z.B[5][13];
3318 <p>The LLVM code generated by the GCC frontend is:</p>
3320 <div class="doc_code">
3322 %RT = type { i8 , [10 x [20 x i32]], i8 }
3323 %ST = type { i32, double, %RT }
3325 define i32* %foo(%ST* %s) {
3327 %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
3335 <p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
3336 on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
3337 and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
3338 <a href="#t_integer">integer</a> type but the value will always be sign extended
3339 to 64-bits. <a href="#t_struct">Structure</a> and <a href="#t_pstruct">packed
3340 structure</a> types require <tt>i32</tt> <b>constants</b>.</p>
3342 <p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
3343 type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
3344 }</tt>' type, a structure. The second index indexes into the third element of
3345 the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
3346 i8 }</tt>' type, another structure. The third index indexes into the second
3347 element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
3348 array. The two dimensions of the array are subscripted into, yielding an
3349 '<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
3350 to this element, thus computing a value of '<tt>i32*</tt>' type.</p>
3352 <p>Note that it is perfectly legal to index partially through a
3353 structure, returning a pointer to an inner element. Because of this,
3354 the LLVM code for the given testcase is equivalent to:</p>
3357 define i32* %foo(%ST* %s) {
3358 %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i>
3359 %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i>
3360 %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i>
3361 %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i>
3362 %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i>
3367 <p>Note that it is undefined to access an array out of bounds: array and
3368 pointer indexes must always be within the defined bounds of the array type.
3369 The one exception for this rule is zero length arrays. These arrays are
3370 defined to be accessible as variable length arrays, which requires access
3371 beyond the zero'th element.</p>
3373 <p>The getelementptr instruction is often confusing. For some more insight
3374 into how it works, see <a href="GetElementPtr.html">the getelementptr
3380 <i>; yields [12 x i8]*:aptr</i>
3381 %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
3385 <!-- ======================================================================= -->
3386 <div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
3388 <div class="doc_text">
3389 <p>The instructions in this category are the conversion instructions (casting)
3390 which all take a single operand and a type. They perform various bit conversions
3394 <!-- _______________________________________________________________________ -->
3395 <div class="doc_subsubsection">
3396 <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
3398 <div class="doc_text">
3402 <result> = trunc <ty> <value> to <ty2> <i>; yields ty2</i>
3407 The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
3412 The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
3413 be an <a href="#t_integer">integer</a> type, and a type that specifies the size
3414 and type of the result, which must be an <a href="#t_integer">integer</a>
3415 type. The bit size of <tt>value</tt> must be larger than the bit size of
3416 <tt>ty2</tt>. Equal sized types are not allowed.</p>
3420 The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
3421 and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
3422 larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
3423 It will always truncate bits.</p>
3427 %X = trunc i32 257 to i8 <i>; yields i8:1</i>
3428 %Y = trunc i32 123 to i1 <i>; yields i1:true</i>
3429 %Y = trunc i32 122 to i1 <i>; yields i1:false</i>
3433 <!-- _______________________________________________________________________ -->
3434 <div class="doc_subsubsection">
3435 <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
3437 <div class="doc_text">
3441 <result> = zext <ty> <value> to <ty2> <i>; yields ty2</i>
3445 <p>The '<tt>zext</tt>' instruction zero extends its operand to type
3450 <p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of
3451 <a href="#t_integer">integer</a> type, and a type to cast it to, which must
3452 also be of <a href="#t_integer">integer</a> type. The bit size of the
3453 <tt>value</tt> must be smaller than the bit size of the destination type,
3457 <p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
3458 bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>
3460 <p>When zero extending from i1, the result will always be either 0 or 1.</p>
3464 %X = zext i32 257 to i64 <i>; yields i64:257</i>
3465 %Y = zext i1 true to i32 <i>; yields i32:1</i>
3469 <!-- _______________________________________________________________________ -->
3470 <div class="doc_subsubsection">
3471 <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
3473 <div class="doc_text">
3477 <result> = sext <ty> <value> to <ty2> <i>; yields ty2</i>
3481 <p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
3485 The '<tt>sext</tt>' instruction takes a value to cast, which must be of
3486 <a href="#t_integer">integer</a> type, and a type to cast it to, which must
3487 also be of <a href="#t_integer">integer</a> type. The bit size of the
3488 <tt>value</tt> must be smaller than the bit size of the destination type,
3493 The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
3494 bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
3495 the type <tt>ty2</tt>.</p>
3497 <p>When sign extending from i1, the extension always results in -1 or 0.</p>
3501 %X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
3502 %Y = sext i1 true to i32 <i>; yields i32:-1</i>
3506 <!-- _______________________________________________________________________ -->
3507 <div class="doc_subsubsection">
3508 <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
3511 <div class="doc_text">
3516 <result> = fptrunc <ty> <value> to <ty2> <i>; yields ty2</i>
3520 <p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
3525 <p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
3526 point</a> value to cast and a <a href="#t_floating">floating point</a> type to
3527 cast it to. The size of <tt>value</tt> must be larger than the size of
3528 <tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a
3529 <i>no-op cast</i>.</p>
3532 <p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
3533 <a href="#t_floating">floating point</a> type to a smaller
3534 <a href="#t_floating">floating point</a> type. If the value cannot fit within
3535 the destination type, <tt>ty2</tt>, then the results are undefined.</p>
3539 %X = fptrunc double 123.0 to float <i>; yields float:123.0</i>
3540 %Y = fptrunc double 1.0E+300 to float <i>; yields undefined</i>
3544 <!-- _______________________________________________________________________ -->
3545 <div class="doc_subsubsection">
3546 <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
3548 <div class="doc_text">
3552 <result> = fpext <ty> <value> to <ty2> <i>; yields ty2</i>
3556 <p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
3557 floating point value.</p>
3560 <p>The '<tt>fpext</tt>' instruction takes a
3561 <a href="#t_floating">floating point</a> <tt>value</tt> to cast,
3562 and a <a href="#t_floating">floating point</a> type to cast it to. The source
3563 type must be smaller than the destination type.</p>
3566 <p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
3567 <a href="#t_floating">floating point</a> type to a larger
3568 <a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be
3569 used to make a <i>no-op cast</i> because it always changes bits. Use
3570 <tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>
3574 %X = fpext float 3.1415 to double <i>; yields double:3.1415</i>
3575 %Y = fpext float 1.0 to float <i>; yields float:1.0 (no-op)</i>
3579 <!-- _______________________________________________________________________ -->
3580 <div class="doc_subsubsection">
3581 <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
3583 <div class="doc_text">
3587 <result> = fptoui <ty> <value> to <ty2> <i>; yields ty2</i>
3591 <p>The '<tt>fptoui</tt>' converts a floating point <tt>value</tt> to its
3592 unsigned integer equivalent of type <tt>ty2</tt>.
3596 <p>The '<tt>fptoui</tt>' instruction takes a value to cast, which must be a
3597 scalar or vector <a href="#t_floating">floating point</a> value, and a type
3598 to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3599 type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3600 vector integer type with the same number of elements as <tt>ty</tt></p>
3603 <p> The '<tt>fptoui</tt>' instruction converts its
3604 <a href="#t_floating">floating point</a> operand into the nearest (rounding
3605 towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
3606 the results are undefined.</p>
3610 %X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
3611 %Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
3612 %X = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
3616 <!-- _______________________________________________________________________ -->
3617 <div class="doc_subsubsection">
3618 <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
3620 <div class="doc_text">
3624 <result> = fptosi <ty> <value> to <ty2> <i>; yields ty2</i>
3628 <p>The '<tt>fptosi</tt>' instruction converts
3629 <a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
3633 <p> The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a
3634 scalar or vector <a href="#t_floating">floating point</a> value, and a type
3635 to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
3636 type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
3637 vector integer type with the same number of elements as <tt>ty</tt></p>
3640 <p>The '<tt>fptosi</tt>' instruction converts its
3641 <a href="#t_floating">floating point</a> operand into the nearest (rounding
3642 towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
3643 the results are undefined.</p>
3647 %X = fptosi double -123.0 to i32 <i>; yields i32:-123</i>
3648 %Y = fptosi float 1.0E-247 to i1 <i>; yields undefined:1</i>
3649 %X = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
3653 <!-- _______________________________________________________________________ -->
3654 <div class="doc_subsubsection">
3655 <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
3657 <div class="doc_text">
3661 <result> = uitofp <ty> <value> to <ty2> <i>; yields ty2</i>
3665 <p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
3666 integer and converts that value to the <tt>ty2</tt> type.</p>
3669 <p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be a
3670 scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3671 to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3672 type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3673 floating point type with the same number of elements as <tt>ty</tt></p>
3676 <p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
3677 integer quantity and converts it to the corresponding floating point value. If
3678 the value cannot fit in the floating point value, the results are undefined.</p>
3682 %X = uitofp i32 257 to float <i>; yields float:257.0</i>
3683 %Y = uitofp i8 -1 to double <i>; yields double:255.0</i>
3687 <!-- _______________________________________________________________________ -->
3688 <div class="doc_subsubsection">
3689 <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
3691 <div class="doc_text">
3695 <result> = sitofp <ty> <value> to <ty2> <i>; yields ty2</i>
3699 <p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
3700 integer and converts that value to the <tt>ty2</tt> type.</p>
3703 <p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be a
3704 scalar or vector <a href="#t_integer">integer</a> value, and a type to cast it
3705 to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
3706 type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
3707 floating point type with the same number of elements as <tt>ty</tt></p>
3710 <p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
3711 integer quantity and converts it to the corresponding floating point value. If
3712 the value cannot fit in the floating point value, the results are undefined.</p>
3716 %X = sitofp i32 257 to float <i>; yields float:257.0</i>
3717 %Y = sitofp i8 -1 to double <i>; yields double:-1.0</i>
3721 <!-- _______________________________________________________________________ -->
3722 <div class="doc_subsubsection">
3723 <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
3725 <div class="doc_text">
3729 <result> = ptrtoint <ty> <value> to <ty2> <i>; yields ty2</i>
3733 <p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to
3734 the integer type <tt>ty2</tt>.</p>
3737 <p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which
3738 must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
3739 <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type.
3742 <p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
3743 <tt>ty2</tt> by interpreting the pointer value as an integer and either
3744 truncating or zero extending that value to the size of the integer type. If
3745 <tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
3746 <tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
3747 are the same size, then nothing is done (<i>no-op cast</i>) other than a type
3752 %X = ptrtoint i32* %X to i8 <i>; yields truncation on 32-bit architecture</i>
3753 %Y = ptrtoint i32* %x to i64 <i>; yields zero extension on 32-bit architecture</i>
3757 <!-- _______________________________________________________________________ -->
3758 <div class="doc_subsubsection">
3759 <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
3761 <div class="doc_text">
3765 <result> = inttoptr <ty> <value> to <ty2> <i>; yields ty2</i>
3769 <p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to
3770 a pointer type, <tt>ty2</tt>.</p>
3773 <p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
3774 value to cast, and a type to cast it to, which must be a
3775 <a href="#t_pointer">pointer</a> type.
3778 <p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
3779 <tt>ty2</tt> by applying either a zero extension or a truncation depending on
3780 the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
3781 size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
3782 the size of a pointer then a zero extension is done. If they are the same size,
3783 nothing is done (<i>no-op cast</i>).</p>
3787 %X = inttoptr i32 255 to i32* <i>; yields zero extension on 64-bit architecture</i>
3788 %X = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
3789 %Y = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
3793 <!-- _______________________________________________________________________ -->
3794 <div class="doc_subsubsection">
3795 <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
3797 <div class="doc_text">
3801 <result> = bitcast <ty> <value> to <ty2> <i>; yields ty2</i>
3806 <p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3807 <tt>ty2</tt> without changing any bits.</p>
3811 <p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be
3812 a non-aggregate first class value, and a type to cast it to, which must also be
3813 a non-aggregate <a href="#t_firstclass">first class</a> type. The bit sizes of
3815 and the destination type, <tt>ty2</tt>, must be identical. If the source
3816 type is a pointer, the destination type must also be a pointer. This
3817 instruction supports bitwise conversion of vectors to integers and to vectors
3818 of other types (as long as they have the same size).</p>
3821 <p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
3822 <tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with
3823 this conversion. The conversion is done as if the <tt>value</tt> had been
3824 stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
3825 converted to other pointer types with this instruction. To convert pointers to
3826 other types, use the <a href="#i_inttoptr">inttoptr</a> or
3827 <a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>
3831 %X = bitcast i8 255 to i8 <i>; yields i8 :-1</i>
3832 %Y = bitcast i32* %x to sint* <i>; yields sint*:%x</i>
3833 %Z = bitcast <2xint> %V to i64; <i>; yields i64: %V</i>
3837 <!-- ======================================================================= -->
3838 <div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
3839 <div class="doc_text">
3840 <p>The instructions in this category are the "miscellaneous"
3841 instructions, which defy better classification.</p>
3844 <!-- _______________________________________________________________________ -->
3845 <div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
3847 <div class="doc_text">
3849 <pre> <result> = icmp <cond> <ty> <op1>, <op2> <i>; yields {i1} or {<N x i1>}:result</i>
3852 <p>The '<tt>icmp</tt>' instruction returns a boolean value or
3853 a vector of boolean values based on comparison
3854 of its two integer, integer vector, or pointer operands.</p>
3856 <p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
3857 the condition code indicating the kind of comparison to perform. It is not
3858 a value, just a keyword. The possible condition code are:
3860 <li><tt>eq</tt>: equal</li>
3861 <li><tt>ne</tt>: not equal </li>
3862 <li><tt>ugt</tt>: unsigned greater than</li>
3863 <li><tt>uge</tt>: unsigned greater or equal</li>
3864 <li><tt>ult</tt>: unsigned less than</li>
3865 <li><tt>ule</tt>: unsigned less or equal</li>
3866 <li><tt>sgt</tt>: signed greater than</li>
3867 <li><tt>sge</tt>: signed greater or equal</li>
3868 <li><tt>slt</tt>: signed less than</li>
3869 <li><tt>sle</tt>: signed less or equal</li>
3871 <p>The remaining two arguments must be <a href="#t_integer">integer</a> or
3872 <a href="#t_pointer">pointer</a>
3873 or integer <a href="#t_vector">vector</a> typed.
3874 They must also be identical types.</p>
3876 <p>The '<tt>icmp</tt>' compares <tt>op1</tt> and <tt>op2</tt> according to
3877 the condition code given as <tt>cond</tt>. The comparison performed always
3878 yields either an <a href="#t_primitive"><tt>i1</tt></a> or vector of <tt>i1</tt> result, as follows:
3880 <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal,
3881 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3883 <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal,
3884 <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
3885 <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
3886 <tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
3887 <li><tt>uge</tt>: interprets the operands as unsigned values and yields
3888 <tt>true</tt> if <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
3889 <li><tt>ult</tt>: interprets the operands as unsigned values and yields
3890 <tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
3891 <li><tt>ule</tt>: interprets the operands as unsigned values and yields
3892 <tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
3893 <li><tt>sgt</tt>: interprets the operands as signed values and yields
3894 <tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
3895 <li><tt>sge</tt>: interprets the operands as signed values and yields
3896 <tt>true</tt> if <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
3897 <li><tt>slt</tt>: interprets the operands as signed values and yields
3898 <tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
3899 <li><tt>sle</tt>: interprets the operands as signed values and yields
3900 <tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
3902 <p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
3903 values are compared as if they were integers.</p>
3904 <p>If the operands are integer vectors, then they are compared
3905 element by element. The result is an <tt>i1</tt> vector with
3906 the same number of elements as the values being compared.
3907 Otherwise, the result is an <tt>i1</tt>.
3911 <pre> <result> = icmp eq i32 4, 5 <i>; yields: result=false</i>
3912 <result> = icmp ne float* %X, %X <i>; yields: result=false</i>
3913 <result> = icmp ult i16 4, 5 <i>; yields: result=true</i>
3914 <result> = icmp sgt i16 4, 5 <i>; yields: result=false</i>
3915 <result> = icmp ule i16 -4, 5 <i>; yields: result=false</i>
3916 <result> = icmp sge i16 4, 5 <i>; yields: result=false</i>
3920 <!-- _______________________________________________________________________ -->
3921 <div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
3923 <div class="doc_text">
3925 <pre> <result> = fcmp <cond> <ty> <op1>, <op2> <i>; yields {i1} or {<N x i1>}:result</i>
3928 <p>The '<tt>fcmp</tt>' instruction returns a boolean value
3929 or vector of boolean values based on comparison
3932 If the operands are floating point scalars, then the result
3933 type is a boolean (<a href="#t_primitive"><tt>i1</tt></a>).
3935 <p>If the operands are floating point vectors, then the result type
3936 is a vector of boolean with the same number of elements as the
3937 operands being compared.</p>
3939 <p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
3940 the condition code indicating the kind of comparison to perform. It is not
3941 a value, just a keyword. The possible condition code are:
3943 <li><tt>false</tt>: no comparison, always returns false</li>
3944 <li><tt>oeq</tt>: ordered and equal</li>
3945 <li><tt>ogt</tt>: ordered and greater than </li>
3946 <li><tt>oge</tt>: ordered and greater than or equal</li>
3947 <li><tt>olt</tt>: ordered and less than </li>
3948 <li><tt>ole</tt>: ordered and less than or equal</li>
3949 <li><tt>one</tt>: ordered and not equal</li>
3950 <li><tt>ord</tt>: ordered (no nans)</li>
3951 <li><tt>ueq</tt>: unordered or equal</li>
3952 <li><tt>ugt</tt>: unordered or greater than </li>
3953 <li><tt>uge</tt>: unordered or greater than or equal</li>
3954 <li><tt>ult</tt>: unordered or less than </li>
3955 <li><tt>ule</tt>: unordered or less than or equal</li>
3956 <li><tt>une</tt>: unordered or not equal</li>
3957 <li><tt>uno</tt>: unordered (either nans)</li>
3958 <li><tt>true</tt>: no comparison, always returns true</li>
3960 <p><i>Ordered</i> means that neither operand is a QNAN while
3961 <i>unordered</i> means that either operand may be a QNAN.</p>
3962 <p>Each of <tt>val1</tt> and <tt>val2</tt> arguments must be
3963 either a <a href="#t_floating">floating point</a> type
3964 or a <a href="#t_vector">vector</a> of floating point type.
3965 They must have identical types.</p>
3967 <p>The '<tt>fcmp</tt>' instruction compares <tt>op1</tt> and <tt>op2</tt>
3968 according to the condition code given as <tt>cond</tt>.
3969 If the operands are vectors, then the vectors are compared
3971 Each comparison performed
3972 always yields an <a href="#t_primitive">i1</a> result, as follows:
3974 <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
3975 <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3976 <tt>op1</tt> is equal to <tt>op2</tt>.</li>
3977 <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3978 <tt>op1</tt> is greather than <tt>op2</tt>.</li>
3979 <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3980 <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
3981 <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3982 <tt>op1</tt> is less than <tt>op2</tt>.</li>
3983 <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3984 <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
3985 <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
3986 <tt>op1</tt> is not equal to <tt>op2</tt>.</li>
3987 <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
3988 <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or
3989 <tt>op1</tt> is equal to <tt>op2</tt>.</li>
3990 <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
3991 <tt>op1</tt> is greater than <tt>op2</tt>.</li>
3992 <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
3993 <tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
3994 <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
3995 <tt>op1</tt> is less than <tt>op2</tt>.</li>
3996 <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
3997 <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
3998 <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
3999 <tt>op1</tt> is not equal to <tt>op2</tt>.</li>
4000 <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
4001 <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
4005 <pre> <result> = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
4006 <result> = fcmp one float 4.0, 5.0 <i>; yields: result=true</i>
4007 <result> = fcmp olt float 4.0, 5.0 <i>; yields: result=true</i>
4008 <result> = fcmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
4012 <!-- _______________________________________________________________________ -->
4013 <div class="doc_subsubsection">
4014 <a name="i_vicmp">'<tt>vicmp</tt>' Instruction</a>
4016 <div class="doc_text">
4018 <pre> <result> = vicmp <cond> <ty> <op1>, <op2> <i>; yields {ty}:result</i>
4021 <p>The '<tt>vicmp</tt>' instruction returns an integer vector value based on
4022 element-wise comparison of its two integer vector operands.</p>
4024 <p>The '<tt>vicmp</tt>' instruction takes three operands. The first operand is
4025 the condition code indicating the kind of comparison to perform. It is not
4026 a value, just a keyword. The possible condition code are:
4028 <li><tt>eq</tt>: equal</li>
4029 <li><tt>ne</tt>: not equal </li>
4030 <li><tt>ugt</tt>: unsigned greater than</li>
4031 <li><tt>uge</tt>: unsigned greater or equal</li>
4032 <li><tt>ult</tt>: unsigned less than</li>
4033 <li><tt>ule</tt>: unsigned less or equal</li>
4034 <li><tt>sgt</tt>: signed greater than</li>
4035 <li><tt>sge</tt>: signed greater or equal</li>
4036 <li><tt>slt</tt>: signed less than</li>
4037 <li><tt>sle</tt>: signed less or equal</li>
4039 <p>The remaining two arguments must be <a href="#t_vector">vector</a> or
4040 <a href="#t_integer">integer</a> typed. They must also be identical types.</p>
4042 <p>The '<tt>vicmp</tt>' instruction compares <tt>op1</tt> and <tt>op2</tt>
4043 according to the condition code given as <tt>cond</tt>. The comparison yields a
4044 <a href="#t_vector">vector</a> of <a href="#t_integer">integer</a> result, of
4045 identical type as the values being compared. The most significant bit in each
4046 element is 1 if the element-wise comparison evaluates to true, and is 0
4047 otherwise. All other bits of the result are undefined. The condition codes
4048 are evaluated identically to the <a href="#i_icmp">'<tt>icmp</tt>'
4053 <result> = vicmp eq <2 x i32> < i32 4, i32 0>, < i32 5, i32 0> <i>; yields: result=<2 x i32> < i32 0, i32 -1 ></i>
4054 <result> = vicmp ult <2 x i8 > < i8 1, i8 2>, < i8 2, i8 2 > <i>; yields: result=<2 x i8> < i8 -1, i8 0 ></i>
4058 <!-- _______________________________________________________________________ -->
4059 <div class="doc_subsubsection">
4060 <a name="i_vfcmp">'<tt>vfcmp</tt>' Instruction</a>
4062 <div class="doc_text">
4064 <pre> <result> = vfcmp <cond> <ty> <op1>, <op2></pre>
4066 <p>The '<tt>vfcmp</tt>' instruction returns an integer vector value based on
4067 element-wise comparison of its two floating point vector operands. The output
4068 elements have the same width as the input elements.</p>
4070 <p>The '<tt>vfcmp</tt>' instruction takes three operands. The first operand is
4071 the condition code indicating the kind of comparison to perform. It is not
4072 a value, just a keyword. The possible condition code are:
4074 <li><tt>false</tt>: no comparison, always returns false</li>
4075 <li><tt>oeq</tt>: ordered and equal</li>
4076 <li><tt>ogt</tt>: ordered and greater than </li>
4077 <li><tt>oge</tt>: ordered and greater than or equal</li>
4078 <li><tt>olt</tt>: ordered and less than </li>
4079 <li><tt>ole</tt>: ordered and less than or equal</li>
4080 <li><tt>one</tt>: ordered and not equal</li>
4081 <li><tt>ord</tt>: ordered (no nans)</li>
4082 <li><tt>ueq</tt>: unordered or equal</li>
4083 <li><tt>ugt</tt>: unordered or greater than </li>
4084 <li><tt>uge</tt>: unordered or greater than or equal</li>
4085 <li><tt>ult</tt>: unordered or less than </li>
4086 <li><tt>ule</tt>: unordered or less than or equal</li>
4087 <li><tt>une</tt>: unordered or not equal</li>
4088 <li><tt>uno</tt>: unordered (either nans)</li>
4089 <li><tt>true</tt>: no comparison, always returns true</li>
4091 <p>The remaining two arguments must be <a href="#t_vector">vector</a> of
4092 <a href="#t_floating">floating point</a> typed. They must also be identical
4095 <p>The '<tt>vfcmp</tt>' instruction compares <tt>op1</tt> and <tt>op2</tt>
4096 according to the condition code given as <tt>cond</tt>. The comparison yields a
4097 <a href="#t_vector">vector</a> of <a href="#t_integer">integer</a> result, with
4098 an identical number of elements as the values being compared, and each element
4099 having identical with to the width of the floating point elements. The most
4100 significant bit in each element is 1 if the element-wise comparison evaluates to
4101 true, and is 0 otherwise. All other bits of the result are undefined. The
4102 condition codes are evaluated identically to the
4103 <a href="#i_fcmp">'<tt>fcmp</tt>' instruction</a>.
4107 <result> = vfcmp oeq <2 x float> < float 4, float 0 >, < float 5, float 0 > <i>; yields: result=<2 x i32> < i32 0, i32 -1 ></i>
4108 <result> = vfcmp ult <2 x double> < double 1, double 2 >, < double 2, double 2> <i>; yields: result=<2 x i64> < i64 -1, i64 0 ></i>
4112 <!-- _______________________________________________________________________ -->
4113 <div class="doc_subsubsection">
4114 <a name="i_phi">'<tt>phi</tt>' Instruction</a>
4117 <div class="doc_text">
4121 <pre> <result> = phi <ty> [ <val0>, <label0>], ...<br></pre>
4123 <p>The '<tt>phi</tt>' instruction is used to implement the φ node in
4124 the SSA graph representing the function.</p>
4127 <p>The type of the incoming values is specified with the first type
4128 field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
4129 as arguments, with one pair for each predecessor basic block of the
4130 current block. Only values of <a href="#t_firstclass">first class</a>
4131 type may be used as the value arguments to the PHI node. Only labels
4132 may be used as the label arguments.</p>
4134 <p>There must be no non-phi instructions between the start of a basic
4135 block and the PHI instructions: i.e. PHI instructions must be first in
4140 <p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
4141 specified by the pair corresponding to the predecessor basic block that executed
4142 just prior to the current block.</p>
4146 Loop: ; Infinite loop that counts from 0 on up...
4147 %indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
4148 %nextindvar = add i32 %indvar, 1
4153 <!-- _______________________________________________________________________ -->
4154 <div class="doc_subsubsection">
4155 <a name="i_select">'<tt>select</tt>' Instruction</a>
4158 <div class="doc_text">
4163 <result> = select <i>selty</i> <cond>, <ty> <val1>, <ty> <val2> <i>; yields ty</i>
4165 <i>selty</i> is either i1 or {<N x i1>}
4171 The '<tt>select</tt>' instruction is used to choose one value based on a
4172 condition, without branching.
4179 The '<tt>select</tt>' instruction requires an 'i1' value or
4180 a vector of 'i1' values indicating the
4181 condition, and two values of the same <a href="#t_firstclass">first class</a>
4182 type. If the val1/val2 are vectors and
4183 the condition is a scalar, then entire vectors are selected, not
4184 individual elements.
4190 If the condition is an i1 and it evaluates to 1, the instruction returns the first
4191 value argument; otherwise, it returns the second value argument.
4194 If the condition is a vector of i1, then the value arguments must
4195 be vectors of the same size, and the selection is done element
4202 %X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
4207 <!-- _______________________________________________________________________ -->
4208 <div class="doc_subsubsection">
4209 <a name="i_call">'<tt>call</tt>' Instruction</a>
4212 <div class="doc_text">
4216 <result> = [tail] call [<a href="#callingconv">cconv</a>] <ty> [<fnty>*] <fnptrval>(<param list>)
4221 <p>The '<tt>call</tt>' instruction represents a simple function call.</p>
4225 <p>This instruction requires several arguments:</p>
4229 <p>The optional "tail" marker indicates whether the callee function accesses
4230 any allocas or varargs in the caller. If the "tail" marker is present, the
4231 function call is eligible for tail call optimization. Note that calls may
4232 be marked "tail" even if they do not occur before a <a
4233 href="#i_ret"><tt>ret</tt></a> instruction.
4236 <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
4237 convention</a> the call should use. If none is specified, the call defaults
4238 to using C calling conventions.
4241 <p>'<tt>ty</tt>': the type of the call instruction itself which is also
4242 the type of the return value. Functions that return no value are marked
4243 <tt><a href="#t_void">void</a></tt>.</p>
4246 <p>'<tt>fnty</tt>': shall be the signature of the pointer to function
4247 value being invoked. The argument types must match the types implied by
4248 this signature. This type can be omitted if the function is not varargs
4249 and if the function type does not return a pointer to a function.</p>
4252 <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
4253 be invoked. In most cases, this is a direct function invocation, but
4254 indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
4255 to function value.</p>
4258 <p>'<tt>function args</tt>': argument list whose types match the
4259 function signature argument types. All arguments must be of
4260 <a href="#t_firstclass">first class</a> type. If the function signature
4261 indicates the function accepts a variable number of arguments, the extra
4262 arguments can be specified.</p>
4268 <p>The '<tt>call</tt>' instruction is used to cause control flow to
4269 transfer to a specified function, with its incoming arguments bound to
4270 the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
4271 instruction in the called function, control flow continues with the
4272 instruction after the function call, and the return value of the
4273 function is bound to the result argument. If the callee returns multiple
4274 values then the return values of the function are only accessible through
4275 the '<tt><a href="#i_getresult">getresult</a></tt>' instruction.</p>
4280 %retval = call i32 @test(i32 %argc)
4281 call i32 (i8 *, ...)* @printf(i8 * %msg, i32 12, i8 42) <i>; yields i32</i>
4282 %X = tail call i32 @foo() <i>; yields i32</i>
4283 %Y = tail call <a href="#callingconv">fastcc</a> i32 @foo() <i>; yields i32</i>
4284 call void %foo(i8 97 signext)
4286 %struct.A = type { i32, i8 }
4287 %r = call %struct.A @foo() <i>; yields { 32, i8 }</i>
4288 %gr = getresult %struct.A %r, 0 <i>; yields i32</i>
4289 %gr1 = getresult %struct.A %r, 1 <i>; yields i8</i>
4294 <!-- _______________________________________________________________________ -->
4295 <div class="doc_subsubsection">
4296 <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
4299 <div class="doc_text">
4304 <resultval> = va_arg <va_list*> <arglist>, <argty>
4309 <p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
4310 the "variable argument" area of a function call. It is used to implement the
4311 <tt>va_arg</tt> macro in C.</p>
4315 <p>This instruction takes a <tt>va_list*</tt> value and the type of
4316 the argument. It returns a value of the specified argument type and
4317 increments the <tt>va_list</tt> to point to the next argument. The
4318 actual type of <tt>va_list</tt> is target specific.</p>
4322 <p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
4323 type from the specified <tt>va_list</tt> and causes the
4324 <tt>va_list</tt> to point to the next argument. For more information,
4325 see the variable argument handling <a href="#int_varargs">Intrinsic
4328 <p>It is legal for this instruction to be called in a function which does not
4329 take a variable number of arguments, for example, the <tt>vfprintf</tt>
4332 <p><tt>va_arg</tt> is an LLVM instruction instead of an <a
4333 href="#intrinsics">intrinsic function</a> because it takes a type as an
4338 <p>See the <a href="#int_varargs">variable argument processing</a> section.</p>
4342 <!-- _______________________________________________________________________ -->
4343 <div class="doc_subsubsection">
4344 <a name="i_getresult">'<tt>getresult</tt>' Instruction</a>
4347 <div class="doc_text">
4351 <resultval> = getresult <type> <retval>, <index>
4356 <p> The '<tt>getresult</tt>' instruction is used to extract individual values
4357 from a '<tt><a href="#i_call">call</a></tt>'
4358 or '<tt><a href="#i_invoke">invoke</a></tt>' instruction that returns multiple
4363 <p>The '<tt>getresult</tt>' instruction takes a call or invoke value as its
4364 first argument, or an undef value. The value must have <a
4365 href="#t_struct">structure type</a>. The second argument is a constant
4366 unsigned index value which must be in range for the number of values returned
4371 <p>The '<tt>getresult</tt>' instruction extracts the element identified by
4372 '<tt>index</tt>' from the aggregate value.</p>
4377 %struct.A = type { i32, i8 }
4379 %r = call %struct.A @foo()
4380 %gr = getresult %struct.A %r, 0 <i>; yields i32:%gr</i>
4381 %gr1 = getresult %struct.A %r, 1 <i>; yields i8:%gr1</i>
4388 <!-- *********************************************************************** -->
4389 <div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
4390 <!-- *********************************************************************** -->
4392 <div class="doc_text">
4394 <p>LLVM supports the notion of an "intrinsic function". These functions have
4395 well known names and semantics and are required to follow certain restrictions.
4396 Overall, these intrinsics represent an extension mechanism for the LLVM
4397 language that does not require changing all of the transformations in LLVM when
4398 adding to the language (or the bitcode reader/writer, the parser, etc...).</p>
4400 <p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
4401 prefix is reserved in LLVM for intrinsic names; thus, function names may not
4402 begin with this prefix. Intrinsic functions must always be external functions:
4403 you cannot define the body of intrinsic functions. Intrinsic functions may
4404 only be used in call or invoke instructions: it is illegal to take the address
4405 of an intrinsic function. Additionally, because intrinsic functions are part
4406 of the LLVM language, it is required if any are added that they be documented
4409 <p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents
4410 a family of functions that perform the same operation but on different data
4411 types. Because LLVM can represent over 8 million different integer types,
4412 overloading is used commonly to allow an intrinsic function to operate on any
4413 integer type. One or more of the argument types or the result type can be
4414 overloaded to accept any integer type. Argument types may also be defined as
4415 exactly matching a previous argument's type or the result type. This allows an
4416 intrinsic function which accepts multiple arguments, but needs all of them to
4417 be of the same type, to only be overloaded with respect to a single argument or
4420 <p>Overloaded intrinsics will have the names of its overloaded argument types
4421 encoded into its function name, each preceded by a period. Only those types
4422 which are overloaded result in a name suffix. Arguments whose type is matched
4423 against another type do not. For example, the <tt>llvm.ctpop</tt> function can
4424 take an integer of any width and returns an integer of exactly the same integer
4425 width. This leads to a family of functions such as
4426 <tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29 %val)</tt>.
4427 Only one type, the return type, is overloaded, and only one type suffix is
4428 required. Because the argument's type is matched against the return type, it
4429 does not require its own name suffix.</p>
4431 <p>To learn how to add an intrinsic function, please see the
4432 <a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
4437 <!-- ======================================================================= -->
4438 <div class="doc_subsection">
4439 <a name="int_varargs">Variable Argument Handling Intrinsics</a>
4442 <div class="doc_text">
4444 <p>Variable argument support is defined in LLVM with the <a
4445 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
4446 intrinsic functions. These functions are related to the similarly
4447 named macros defined in the <tt><stdarg.h></tt> header file.</p>
4449 <p>All of these functions operate on arguments that use a
4450 target-specific value type "<tt>va_list</tt>". The LLVM assembly
4451 language reference manual does not define what this type is, so all
4452 transformations should be prepared to handle these functions regardless of
4455 <p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
4456 instruction and the variable argument handling intrinsic functions are
4459 <div class="doc_code">
4461 define i32 @test(i32 %X, ...) {
4462 ; Initialize variable argument processing
4464 %ap2 = bitcast i8** %ap to i8*
4465 call void @llvm.va_start(i8* %ap2)
4467 ; Read a single integer argument
4468 %tmp = va_arg i8** %ap, i32
4470 ; Demonstrate usage of llvm.va_copy and llvm.va_end
4472 %aq2 = bitcast i8** %aq to i8*
4473 call void @llvm.va_copy(i8* %aq2, i8* %ap2)
4474 call void @llvm.va_end(i8* %aq2)
4476 ; Stop processing of arguments.
4477 call void @llvm.va_end(i8* %ap2)
4481 declare void @llvm.va_start(i8*)
4482 declare void @llvm.va_copy(i8*, i8*)
4483 declare void @llvm.va_end(i8*)
4489 <!-- _______________________________________________________________________ -->
4490 <div class="doc_subsubsection">
4491 <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
4495 <div class="doc_text">
4497 <pre> declare void %llvm.va_start(i8* <arglist>)<br></pre>
4499 <P>The '<tt>llvm.va_start</tt>' intrinsic initializes
4500 <tt>*<arglist></tt> for subsequent use by <tt><a
4501 href="#i_va_arg">va_arg</a></tt>.</p>
4505 <P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>
4509 <P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
4510 macro available in C. In a target-dependent way, it initializes the
4511 <tt>va_list</tt> element to which the argument points, so that the next call to
4512 <tt>va_arg</tt> will produce the first variable argument passed to the function.
4513 Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
4514 last argument of the function as the compiler can figure that out.</p>
4518 <!-- _______________________________________________________________________ -->
4519 <div class="doc_subsubsection">
4520 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
4523 <div class="doc_text">
4525 <pre> declare void @llvm.va_end(i8* <arglist>)<br></pre>
4528 <p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*<arglist></tt>,
4529 which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
4530 or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>
4534 <p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>
4538 <p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
4539 macro available in C. In a target-dependent way, it destroys the
4540 <tt>va_list</tt> element to which the argument points. Calls to <a
4541 href="#int_va_start"><tt>llvm.va_start</tt></a> and <a href="#int_va_copy">
4542 <tt>llvm.va_copy</tt></a> must be matched exactly with calls to
4543 <tt>llvm.va_end</tt>.</p>
4547 <!-- _______________________________________________________________________ -->
4548 <div class="doc_subsubsection">
4549 <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
4552 <div class="doc_text">
4557 declare void @llvm.va_copy(i8* <destarglist>, i8* <srcarglist>)
4562 <p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
4563 from the source argument list to the destination argument list.</p>
4567 <p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
4568 The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>
4573 <p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
4574 macro available in C. In a target-dependent way, it copies the source
4575 <tt>va_list</tt> element into the destination <tt>va_list</tt> element. This
4576 intrinsic is necessary because the <tt><a href="#int_va_start">
4577 llvm.va_start</a></tt> intrinsic may be arbitrarily complex and require, for
4578 example, memory allocation.</p>
4582 <!-- ======================================================================= -->
4583 <div class="doc_subsection">
4584 <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
4587 <div class="doc_text">
4590 LLVM support for <a href="GarbageCollection.html">Accurate Garbage
4591 Collection</a> (GC) requires the implementation and generation of these
4593 These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
4594 stack</a>, as well as garbage collector implementations that require <a
4595 href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
4596 Front-ends for type-safe garbage collected languages should generate these
4597 intrinsics to make use of the LLVM garbage collectors. For more details, see <a
4598 href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
4601 <p>The garbage collection intrinsics only operate on objects in the generic
4602 address space (address space zero).</p>
4606 <!-- _______________________________________________________________________ -->
4607 <div class="doc_subsubsection">
4608 <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
4611 <div class="doc_text">
4616 declare void @llvm.gcroot(i8** %ptrloc, i8* %metadata)
4621 <p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
4622 the code generator, and allows some metadata to be associated with it.</p>
4626 <p>The first argument specifies the address of a stack object that contains the
4627 root pointer. The second pointer (which must be either a constant or a global
4628 value address) contains the meta-data to be associated with the root.</p>
4632 <p>At runtime, a call to this intrinsic stores a null pointer into the "ptrloc"
4633 location. At compile-time, the code generator generates information to allow
4634 the runtime to find the pointer at GC safe points. The '<tt>llvm.gcroot</tt>'
4635 intrinsic may only be used in a function which <a href="#gc">specifies a GC
4641 <!-- _______________________________________________________________________ -->
4642 <div class="doc_subsubsection">
4643 <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
4646 <div class="doc_text">
4651 declare i8* @llvm.gcread(i8* %ObjPtr, i8** %Ptr)
4656 <p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
4657 locations, allowing garbage collector implementations that require read
4662 <p>The second argument is the address to read from, which should be an address
4663 allocated from the garbage collector. The first object is a pointer to the
4664 start of the referenced object, if needed by the language runtime (otherwise
4669 <p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
4670 instruction, but may be replaced with substantially more complex code by the
4671 garbage collector runtime, as needed. The '<tt>llvm.gcread</tt>' intrinsic
4672 may only be used in a function which <a href="#gc">specifies a GC
4678 <!-- _______________________________________________________________________ -->
4679 <div class="doc_subsubsection">
4680 <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
4683 <div class="doc_text">
4688 declare void @llvm.gcwrite(i8* %P1, i8* %Obj, i8** %P2)
4693 <p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
4694 locations, allowing garbage collector implementations that require write
4695 barriers (such as generational or reference counting collectors).</p>
4699 <p>The first argument is the reference to store, the second is the start of the
4700 object to store it to, and the third is the address of the field of Obj to
4701 store to. If the runtime does not require a pointer to the object, Obj may be
4706 <p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
4707 instruction, but may be replaced with substantially more complex code by the
4708 garbage collector runtime, as needed. The '<tt>llvm.gcwrite</tt>' intrinsic
4709 may only be used in a function which <a href="#gc">specifies a GC
4716 <!-- ======================================================================= -->
4717 <div class="doc_subsection">
4718 <a name="int_codegen">Code Generator Intrinsics</a>
4721 <div class="doc_text">
4723 These intrinsics are provided by LLVM to expose special features that may only
4724 be implemented with code generator support.
4729 <!-- _______________________________________________________________________ -->
4730 <div class="doc_subsubsection">
4731 <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
4734 <div class="doc_text">
4738 declare i8 *@llvm.returnaddress(i32 <level>)
4744 The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a
4745 target-specific value indicating the return address of the current function
4746 or one of its callers.
4752 The argument to this intrinsic indicates which function to return the address
4753 for. Zero indicates the calling function, one indicates its caller, etc. The
4754 argument is <b>required</b> to be a constant integer value.
4760 The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
4761 the return address of the specified call frame, or zero if it cannot be
4762 identified. The value returned by this intrinsic is likely to be incorrect or 0
4763 for arguments other than zero, so it should only be used for debugging purposes.
4767 Note that calling this intrinsic does not prevent function inlining or other
4768 aggressive transformations, so the value returned may not be that of the obvious
4769 source-language caller.
4774 <!-- _______________________________________________________________________ -->
4775 <div class="doc_subsubsection">
4776 <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
4779 <div class="doc_text">
4783 declare i8 *@llvm.frameaddress(i32 <level>)
4789 The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the
4790 target-specific frame pointer value for the specified stack frame.
4796 The argument to this intrinsic indicates which function to return the frame
4797 pointer for. Zero indicates the calling function, one indicates its caller,
4798 etc. The argument is <b>required</b> to be a constant integer value.
4804 The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
4805 the frame address of the specified call frame, or zero if it cannot be
4806 identified. The value returned by this intrinsic is likely to be incorrect or 0
4807 for arguments other than zero, so it should only be used for debugging purposes.
4811 Note that calling this intrinsic does not prevent function inlining or other
4812 aggressive transformations, so the value returned may not be that of the obvious
4813 source-language caller.
4817 <!-- _______________________________________________________________________ -->
4818 <div class="doc_subsubsection">
4819 <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
4822 <div class="doc_text">
4826 declare i8 *@llvm.stacksave()
4832 The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
4833 the function stack, for use with <a href="#int_stackrestore">
4834 <tt>llvm.stackrestore</tt></a>. This is useful for implementing language
4835 features like scoped automatic variable sized arrays in C99.
4841 This intrinsic returns a opaque pointer value that can be passed to <a
4842 href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>. When an
4843 <tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from
4844 <tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
4845 state it was in when the <tt>llvm.stacksave</tt> intrinsic executed. In
4846 practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
4847 that were allocated after the <tt>llvm.stacksave</tt> was executed.
4852 <!-- _______________________________________________________________________ -->
4853 <div class="doc_subsubsection">
4854 <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
4857 <div class="doc_text">
4861 declare void @llvm.stackrestore(i8 * %ptr)
4867 The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
4868 the function stack to the state it was in when the corresponding <a
4869 href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed. This is
4870 useful for implementing language features like scoped automatic variable sized
4877 See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
4883 <!-- _______________________________________________________________________ -->
4884 <div class="doc_subsubsection">
4885 <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
4888 <div class="doc_text">
4892 declare void @llvm.prefetch(i8* <address>, i32 <rw>, i32 <locality>)
4899 The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
4900 a prefetch instruction if supported; otherwise, it is a noop. Prefetches have
4902 effect on the behavior of the program but can change its performance
4909 <tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
4910 determining if the fetch should be for a read (0) or write (1), and
4911 <tt>locality</tt> is a temporal locality specifier ranging from (0) - no
4912 locality, to (3) - extremely local keep in cache. The <tt>rw</tt> and
4913 <tt>locality</tt> arguments must be constant integers.
4919 This intrinsic does not modify the behavior of the program. In particular,
4920 prefetches cannot trap and do not produce a value. On targets that support this
4921 intrinsic, the prefetch can provide hints to the processor cache for better
4927 <!-- _______________________________________________________________________ -->
4928 <div class="doc_subsubsection">
4929 <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
4932 <div class="doc_text">
4936 declare void @llvm.pcmarker(i32 <id>)
4943 The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
4945 code to simulators and other tools. The method is target specific, but it is
4946 expected that the marker will use exported symbols to transmit the PC of the
4948 The marker makes no guarantees that it will remain with any specific instruction
4949 after optimizations. It is possible that the presence of a marker will inhibit
4950 optimizations. The intended use is to be inserted after optimizations to allow
4951 correlations of simulation runs.
4957 <tt>id</tt> is a numerical id identifying the marker.
4963 This intrinsic does not modify the behavior of the program. Backends that do not
4964 support this intrinisic may ignore it.
4969 <!-- _______________________________________________________________________ -->
4970 <div class="doc_subsubsection">
4971 <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
4974 <div class="doc_text">
4978 declare i64 @llvm.readcyclecounter( )
4985 The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle
4986 counter register (or similar low latency, high accuracy clocks) on those targets
4987 that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC.
4988 As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
4989 should only be used for small timings.
4995 When directly supported, reading the cycle counter should not modify any memory.
4996 Implementations are allowed to either return a application specific value or a
4997 system wide value. On backends without support, this is lowered to a constant 0.
5002 <!-- ======================================================================= -->
5003 <div class="doc_subsection">
5004 <a name="int_libc">Standard C Library Intrinsics</a>
5007 <div class="doc_text">
5009 LLVM provides intrinsics for a few important standard C library functions.
5010 These intrinsics allow source-language front-ends to pass information about the
5011 alignment of the pointer arguments to the code generator, providing opportunity
5012 for more efficient code generation.
5017 <!-- _______________________________________________________________________ -->
5018 <div class="doc_subsubsection">
5019 <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
5022 <div class="doc_text">
5026 declare void @llvm.memcpy.i32(i8 * <dest>, i8 * <src>,
5027 i32 <len>, i32 <align>)
5028 declare void @llvm.memcpy.i64(i8 * <dest>, i8 * <src>,
5029 i64 <len>, i32 <align>)
5035 The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
5036 location to the destination location.
5040 Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt>
5041 intrinsics do not return a value, and takes an extra alignment argument.
5047 The first argument is a pointer to the destination, the second is a pointer to
5048 the source. The third argument is an integer argument
5049 specifying the number of bytes to copy, and the fourth argument is the alignment
5050 of the source and destination locations.
5054 If the call to this intrinisic has an alignment value that is not 0 or 1, then
5055 the caller guarantees that both the source and destination pointers are aligned
5062 The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
5063 location to the destination location, which are not allowed to overlap. It
5064 copies "len" bytes of memory over. If the argument is known to be aligned to
5065 some boundary, this can be specified as the fourth argument, otherwise it should
5071 <!-- _______________________________________________________________________ -->
5072 <div class="doc_subsubsection">
5073 <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
5076 <div class="doc_text">
5080 declare void @llvm.memmove.i32(i8 * <dest>, i8 * <src>,
5081 i32 <len>, i32 <align>)
5082 declare void @llvm.memmove.i64(i8 * <dest>, i8 * <src>,
5083 i64 <len>, i32 <align>)
5089 The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
5090 location to the destination location. It is similar to the
5091 '<tt>llvm.memcpy</tt>' intrinsic but allows the two memory locations to overlap.
5095 Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt>
5096 intrinsics do not return a value, and takes an extra alignment argument.
5102 The first argument is a pointer to the destination, the second is a pointer to
5103 the source. The third argument is an integer argument
5104 specifying the number of bytes to copy, and the fourth argument is the alignment
5105 of the source and destination locations.
5109 If the call to this intrinisic has an alignment value that is not 0 or 1, then
5110 the caller guarantees that the source and destination pointers are aligned to
5117 The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
5118 location to the destination location, which may overlap. It
5119 copies "len" bytes of memory over. If the argument is known to be aligned to
5120 some boundary, this can be specified as the fourth argument, otherwise it should
5126 <!-- _______________________________________________________________________ -->
5127 <div class="doc_subsubsection">
5128 <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
5131 <div class="doc_text">
5135 declare void @llvm.memset.i32(i8 * <dest>, i8 <val>,
5136 i32 <len>, i32 <align>)
5137 declare void @llvm.memset.i64(i8 * <dest>, i8 <val>,
5138 i64 <len>, i32 <align>)
5144 The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
5149 Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
5150 does not return a value, and takes an extra alignment argument.
5156 The first argument is a pointer to the destination to fill, the second is the
5157 byte value to fill it with, the third argument is an integer
5158 argument specifying the number of bytes to fill, and the fourth argument is the
5159 known alignment of destination location.
5163 If the call to this intrinisic has an alignment value that is not 0 or 1, then
5164 the caller guarantees that the destination pointer is aligned to that boundary.
5170 The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
5172 destination location. If the argument is known to be aligned to some boundary,
5173 this can be specified as the fourth argument, otherwise it should be set to 0 or
5179 <!-- _______________________________________________________________________ -->
5180 <div class="doc_subsubsection">
5181 <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
5184 <div class="doc_text">
5187 <p>This is an overloaded intrinsic. You can use <tt>llvm.sqrt</tt> on any
5188 floating point or vector of floating point type. Not all targets support all
5191 declare float @llvm.sqrt.f32(float %Val)
5192 declare double @llvm.sqrt.f64(double %Val)
5193 declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
5194 declare fp128 @llvm.sqrt.f128(fp128 %Val)
5195 declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %Val)
5201 The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
5202 returning the same value as the libm '<tt>sqrt</tt>' functions would. Unlike
5203 <tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
5204 negative numbers other than -0.0 (which allows for better optimization, because
5205 there is no need to worry about errno being set). <tt>llvm.sqrt(-0.0)</tt> is
5206 defined to return -0.0 like IEEE sqrt.
5212 The argument and return value are floating point numbers of the same type.
5218 This function returns the sqrt of the specified operand if it is a nonnegative
5219 floating point number.
5223 <!-- _______________________________________________________________________ -->
5224 <div class="doc_subsubsection">
5225 <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
5228 <div class="doc_text">
5231 <p>This is an overloaded intrinsic. You can use <tt>llvm.powi</tt> on any
5232 floating point or vector of floating point type. Not all targets support all
5235 declare float @llvm.powi.f32(float %Val, i32 %power)
5236 declare double @llvm.powi.f64(double %Val, i32 %power)
5237 declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
5238 declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
5239 declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %Val, i32 %power)
5245 The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
5246 specified (positive or negative) power. The order of evaluation of
5247 multiplications is not defined. When a vector of floating point type is
5248 used, the second argument remains a scalar integer value.
5254 The second argument is an integer power, and the first is a value to raise to
5261 This function returns the first value raised to the second power with an
5262 unspecified sequence of rounding operations.</p>
5265 <!-- _______________________________________________________________________ -->
5266 <div class="doc_subsubsection">
5267 <a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
5270 <div class="doc_text">
5273 <p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
5274 floating point or vector of floating point type. Not all targets support all
5277 declare float @llvm.sin.f32(float %Val)
5278 declare double @llvm.sin.f64(double %Val)
5279 declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
5280 declare fp128 @llvm.sin.f128(fp128 %Val)
5281 declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
5287 The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.
5293 The argument and return value are floating point numbers of the same type.
5299 This function returns the sine of the specified operand, returning the
5300 same values as the libm <tt>sin</tt> functions would, and handles error
5301 conditions in the same way.</p>
5304 <!-- _______________________________________________________________________ -->
5305 <div class="doc_subsubsection">
5306 <a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
5309 <div class="doc_text">
5312 <p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
5313 floating point or vector of floating point type. Not all targets support all
5316 declare float @llvm.cos.f32(float %Val)
5317 declare double @llvm.cos.f64(double %Val)
5318 declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
5319 declare fp128 @llvm.cos.f128(fp128 %Val)
5320 declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
5326 The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.
5332 The argument and return value are floating point numbers of the same type.
5338 This function returns the cosine of the specified operand, returning the
5339 same values as the libm <tt>cos</tt> functions would, and handles error
5340 conditions in the same way.</p>
5343 <!-- _______________________________________________________________________ -->
5344 <div class="doc_subsubsection">
5345 <a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
5348 <div class="doc_text">
5351 <p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
5352 floating point or vector of floating point type. Not all targets support all
5355 declare float @llvm.pow.f32(float %Val, float %Power)
5356 declare double @llvm.pow.f64(double %Val, double %Power)
5357 declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
5358 declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
5359 declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
5365 The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
5366 specified (positive or negative) power.
5372 The second argument is a floating point power, and the first is a value to
5373 raise to that power.
5379 This function returns the first value raised to the second power,
5381 same values as the libm <tt>pow</tt> functions would, and handles error
5382 conditions in the same way.</p>
5386 <!-- ======================================================================= -->
5387 <div class="doc_subsection">
5388 <a name="int_manip">Bit Manipulation Intrinsics</a>
5391 <div class="doc_text">
5393 LLVM provides intrinsics for a few important bit manipulation operations.
5394 These allow efficient code generation for some algorithms.
5399 <!-- _______________________________________________________________________ -->
5400 <div class="doc_subsubsection">
5401 <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
5404 <div class="doc_text">
5407 <p>This is an overloaded intrinsic function. You can use bswap on any integer
5408 type that is an even number of bytes (i.e. BitWidth % 16 == 0).
5410 declare i16 @llvm.bswap.i16(i16 <id>)
5411 declare i32 @llvm.bswap.i32(i32 <id>)
5412 declare i64 @llvm.bswap.i64(i64 <id>)
5418 The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer
5419 values with an even number of bytes (positive multiple of 16 bits). These are
5420 useful for performing operations on data that is not in the target's native
5427 The <tt>llvm.bswap.i16</tt> intrinsic returns an i16 value that has the high
5428 and low byte of the input i16 swapped. Similarly, the <tt>llvm.bswap.i32</tt>
5429 intrinsic returns an i32 value that has the four bytes of the input i32
5430 swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned
5431 i32 will have its bytes in 3, 2, 1, 0 order. The <tt>llvm.bswap.i48</tt>,
5432 <tt>llvm.bswap.i64</tt> and other intrinsics extend this concept to
5433 additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
5438 <!-- _______________________________________________________________________ -->
5439 <div class="doc_subsubsection">
5440 <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
5443 <div class="doc_text">
5446 <p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
5447 width. Not all targets support all bit widths however.
5449 declare i8 @llvm.ctpop.i8 (i8 <src>)
5450 declare i16 @llvm.ctpop.i16(i16 <src>)
5451 declare i32 @llvm.ctpop.i32(i32 <src>)
5452 declare i64 @llvm.ctpop.i64(i64 <src>)
5453 declare i256 @llvm.ctpop.i256(i256 <src>)
5459 The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a
5466 The only argument is the value to be counted. The argument may be of any
5467 integer type. The return type must match the argument type.
5473 The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
5477 <!-- _______________________________________________________________________ -->
5478 <div class="doc_subsubsection">
5479 <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
5482 <div class="doc_text">
5485 <p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
5486 integer bit width. Not all targets support all bit widths however.
5488 declare i8 @llvm.ctlz.i8 (i8 <src>)
5489 declare i16 @llvm.ctlz.i16(i16 <src>)
5490 declare i32 @llvm.ctlz.i32(i32 <src>)
5491 declare i64 @llvm.ctlz.i64(i64 <src>)
5492 declare i256 @llvm.ctlz.i256(i256 <src>)
5498 The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of
5499 leading zeros in a variable.
5505 The only argument is the value to be counted. The argument may be of any
5506 integer type. The return type must match the argument type.
5512 The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
5513 in a variable. If the src == 0 then the result is the size in bits of the type
5514 of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
5520 <!-- _______________________________________________________________________ -->
5521 <div class="doc_subsubsection">
5522 <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
5525 <div class="doc_text">
5528 <p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
5529 integer bit width. Not all targets support all bit widths however.
5531 declare i8 @llvm.cttz.i8 (i8 <src>)
5532 declare i16 @llvm.cttz.i16(i16 <src>)
5533 declare i32 @llvm.cttz.i32(i32 <src>)
5534 declare i64 @llvm.cttz.i64(i64 <src>)
5535 declare i256 @llvm.cttz.i256(i256 <src>)
5541 The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of
5548 The only argument is the value to be counted. The argument may be of any
5549 integer type. The return type must match the argument type.
5555 The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
5556 in a variable. If the src == 0 then the result is the size in bits of the type
5557 of src. For example, <tt>llvm.cttz(2) = 1</tt>.
5561 <!-- _______________________________________________________________________ -->
5562 <div class="doc_subsubsection">
5563 <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
5566 <div class="doc_text">
5569 <p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt>
5570 on any integer bit width.
5572 declare i17 @llvm.part.select.i17 (i17 %val, i32 %loBit, i32 %hiBit)
5573 declare i29 @llvm.part.select.i29 (i29 %val, i32 %loBit, i32 %hiBit)
5577 <p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
5578 range of bits from an integer value and returns them in the same bit width as
5579 the original value.</p>
5582 <p>The first argument, <tt>%val</tt> and the result may be integer types of
5583 any bit width but they must have the same bit width. The second and third
5584 arguments must be <tt>i32</tt> type since they specify only a bit index.</p>
5587 <p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
5588 of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
5589 <tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
5590 operates in forward mode.</p>
5591 <p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
5592 right by <tt>%loBit</tt> bits and then ANDing it with a mask with
5593 only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
5595 <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
5596 by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
5597 <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
5598 to determine the number of bits to retain.</li>
5599 <li>A mask of the retained bits is created by shifting a -1 value.</li>
5600 <li>The mask is ANDed with <tt>%val</tt> to produce the result.
5602 <p>In reverse mode, a similar computation is made except that the bits are
5603 returned in the reverse order. So, for example, if <tt>X</tt> has the value
5604 <tt>i16 0x0ACF (101011001111)</tt> and we apply
5605 <tt>part.select(i16 X, 8, 3)</tt> to it, we get back the value
5606 <tt>i16 0x0026 (000000100110)</tt>.</p>
5609 <div class="doc_subsubsection">
5610 <a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
5613 <div class="doc_text">
5616 <p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt>
5617 on any integer bit width.
5619 declare i17 @llvm.part.set.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
5620 declare i29 @llvm.part.set.i29.i9 (i29 %val, i9 %repl, i32 %lo, i32 %hi)
5624 <p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
5625 of bits in an integer value with another integer value. It returns the integer
5626 with the replaced bits.</p>
5629 <p>The first argument, <tt>%val</tt> and the result may be integer types of
5630 any bit width but they must have the same bit width. <tt>%val</tt> is the value
5631 whose bits will be replaced. The second argument, <tt>%repl</tt> may be an
5632 integer of any bit width. The third and fourth arguments must be <tt>i32</tt>
5633 type since they specify only a bit index.</p>
5636 <p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
5637 of operation: forwards and reverse. If <tt>%lo</tt> is greater than
5638 <tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
5639 operates in forward mode.</p>
5640 <p>For both modes, the <tt>%repl</tt> value is prepared for use by either
5641 truncating it down to the size of the replacement area or zero extending it
5642 up to that size.</p>
5643 <p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
5644 are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
5645 in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
5646 to the <tt>%hi</tt>th bit.
5647 <p>In reverse mode, a similar computation is made except that the bits are
5648 reversed. That is, the <tt>0</tt>th bit in <tt>%repl</tt> replaces the
5649 <tt>%hi</tt> bit in <tt>%val</tt> and etc. down to the <tt>%lo</tt>th bit.
5652 llvm.part.set(0xFFFF, 0, 4, 7) -> 0xFF0F
5653 llvm.part.set(0xFFFF, 0, 7, 4) -> 0xFF0F
5654 llvm.part.set(0xFFFF, 1, 7, 4) -> 0xFF8F
5655 llvm.part.set(0xFFFF, F, 8, 3) -> 0xFFE7
5656 llvm.part.set(0xFFFF, 0, 3, 8) -> 0xFE07
5660 <!-- ======================================================================= -->
5661 <div class="doc_subsection">
5662 <a name="int_debugger">Debugger Intrinsics</a>
5665 <div class="doc_text">
5667 The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
5668 are described in the <a
5669 href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
5670 Debugging</a> document.
5675 <!-- ======================================================================= -->
5676 <div class="doc_subsection">
5677 <a name="int_eh">Exception Handling Intrinsics</a>
5680 <div class="doc_text">
5681 <p> The LLVM exception handling intrinsics (which all start with
5682 <tt>llvm.eh.</tt> prefix), are described in the <a
5683 href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
5684 Handling</a> document. </p>
5687 <!-- ======================================================================= -->
5688 <div class="doc_subsection">
5689 <a name="int_trampoline">Trampoline Intrinsic</a>
5692 <div class="doc_text">
5694 This intrinsic makes it possible to excise one parameter, marked with
5695 the <tt>nest</tt> attribute, from a function. The result is a callable
5696 function pointer lacking the nest parameter - the caller does not need
5697 to provide a value for it. Instead, the value to use is stored in
5698 advance in a "trampoline", a block of memory usually allocated
5699 on the stack, which also contains code to splice the nest value into the
5700 argument list. This is used to implement the GCC nested function address
5704 For example, if the function is
5705 <tt>i32 f(i8* nest %c, i32 %x, i32 %y)</tt> then the resulting function
5706 pointer has signature <tt>i32 (i32, i32)*</tt>. It can be created as follows:</p>
5708 %tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
5709 %tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
5710 %p = call i8* @llvm.init.trampoline( i8* %tramp1, i8* bitcast (i32 (i8* nest , i32, i32)* @f to i8*), i8* %nval )
5711 %fp = bitcast i8* %p to i32 (i32, i32)*
5713 <p>The call <tt>%val = call i32 %fp( i32 %x, i32 %y )</tt> is then equivalent
5714 to <tt>%val = call i32 %f( i8* %nval, i32 %x, i32 %y )</tt>.</p>
5717 <!-- _______________________________________________________________________ -->
5718 <div class="doc_subsubsection">
5719 <a name="int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a>
5721 <div class="doc_text">
5724 declare i8* @llvm.init.trampoline(i8* <tramp>, i8* <func>, i8* <nval>)
5728 This fills the memory pointed to by <tt>tramp</tt> with code
5729 and returns a function pointer suitable for executing it.
5733 The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
5734 pointers. The <tt>tramp</tt> argument must point to a sufficiently large
5735 and sufficiently aligned block of memory; this memory is written to by the
5736 intrinsic. Note that the size and the alignment are target-specific - LLVM
5737 currently provides no portable way of determining them, so a front-end that
5738 generates this intrinsic needs to have some target-specific knowledge.
5739 The <tt>func</tt> argument must hold a function bitcast to an <tt>i8*</tt>.
5743 The block of memory pointed to by <tt>tramp</tt> is filled with target
5744 dependent code, turning it into a function. A pointer to this function is
5745 returned, but needs to be bitcast to an
5746 <a href="#int_trampoline">appropriate function pointer type</a>
5747 before being called. The new function's signature is the same as that of
5748 <tt>func</tt> with any arguments marked with the <tt>nest</tt> attribute
5749 removed. At most one such <tt>nest</tt> argument is allowed, and it must be
5750 of pointer type. Calling the new function is equivalent to calling
5751 <tt>func</tt> with the same argument list, but with <tt>nval</tt> used for the
5752 missing <tt>nest</tt> argument. If, after calling
5753 <tt>llvm.init.trampoline</tt>, the memory pointed to by <tt>tramp</tt> is
5754 modified, then the effect of any later call to the returned function pointer is
5759 <!-- ======================================================================= -->
5760 <div class="doc_subsection">
5761 <a name="int_atomics">Atomic Operations and Synchronization Intrinsics</a>
5764 <div class="doc_text">
5766 These intrinsic functions expand the "universal IR" of LLVM to represent
5767 hardware constructs for atomic operations and memory synchronization. This
5768 provides an interface to the hardware, not an interface to the programmer. It
5769 is aimed at a low enough level to allow any programming models or APIs
5770 (Application Programming Interfaces) which
5771 need atomic behaviors to map cleanly onto it. It is also modeled primarily on
5772 hardware behavior. Just as hardware provides a "universal IR" for source
5773 languages, it also provides a starting point for developing a "universal"
5774 atomic operation and synchronization IR.
5777 These do <em>not</em> form an API such as high-level threading libraries,
5778 software transaction memory systems, atomic primitives, and intrinsic
5779 functions as found in BSD, GNU libc, atomic_ops, APR, and other system and
5780 application libraries. The hardware interface provided by LLVM should allow
5781 a clean implementation of all of these APIs and parallel programming models.
5782 No one model or paradigm should be selected above others unless the hardware
5783 itself ubiquitously does so.
5788 <!-- _______________________________________________________________________ -->
5789 <div class="doc_subsubsection">
5790 <a name="int_memory_barrier">'<tt>llvm.memory.barrier</tt>' Intrinsic</a>
5792 <div class="doc_text">
5795 declare void @llvm.memory.barrier( i1 <ll>, i1 <ls>, i1 <sl>, i1 <ss>,
5801 The <tt>llvm.memory.barrier</tt> intrinsic guarantees ordering between
5802 specific pairs of memory access types.
5806 The <tt>llvm.memory.barrier</tt> intrinsic requires five boolean arguments.
5807 The first four arguments enables a specific barrier as listed below. The fith
5808 argument specifies that the barrier applies to io or device or uncached memory.
5812 <li><tt>ll</tt>: load-load barrier</li>
5813 <li><tt>ls</tt>: load-store barrier</li>
5814 <li><tt>sl</tt>: store-load barrier</li>
5815 <li><tt>ss</tt>: store-store barrier</li>
5816 <li><tt>device</tt>: barrier applies to device and uncached memory also.
5820 This intrinsic causes the system to enforce some ordering constraints upon
5821 the loads and stores of the program. This barrier does not indicate
5822 <em>when</em> any events will occur, it only enforces an <em>order</em> in
5823 which they occur. For any of the specified pairs of load and store operations
5824 (f.ex. load-load, or store-load), all of the first operations preceding the
5825 barrier will complete before any of the second operations succeeding the
5826 barrier begin. Specifically the semantics for each pairing is as follows:
5829 <li><tt>ll</tt>: All loads before the barrier must complete before any load
5830 after the barrier begins.</li>
5832 <li><tt>ls</tt>: All loads before the barrier must complete before any
5833 store after the barrier begins.</li>
5834 <li><tt>ss</tt>: All stores before the barrier must complete before any
5835 store after the barrier begins.</li>
5836 <li><tt>sl</tt>: All stores before the barrier must complete before any
5837 load after the barrier begins.</li>
5840 These semantics are applied with a logical "and" behavior when more than one
5841 is enabled in a single memory barrier intrinsic.
5844 Backends may implement stronger barriers than those requested when they do not
5845 support as fine grained a barrier as requested. Some architectures do not
5846 need all types of barriers and on such architectures, these become noops.
5853 %result1 = load i32* %ptr <i>; yields {i32}:result1 = 4</i>
5854 call void @llvm.memory.barrier( i1 false, i1 true, i1 false, i1 false )
5855 <i>; guarantee the above finishes</i>
5856 store i32 8, %ptr <i>; before this begins</i>
5860 <!-- _______________________________________________________________________ -->
5861 <div class="doc_subsubsection">
5862 <a name="int_atomic_cmp_swap">'<tt>llvm.atomic.cmp.swap.*</tt>' Intrinsic</a>
5864 <div class="doc_text">
5867 This is an overloaded intrinsic. You can use <tt>llvm.atomic.cmp.swap</tt> on
5868 any integer bit width and for different address spaces. Not all targets
5869 support all bit widths however.</p>
5872 declare i8 @llvm.atomic.cmp.swap.i8.p0i8( i8* <ptr>, i8 <cmp>, i8 <val> )
5873 declare i16 @llvm.atomic.cmp.swap.i16.p0i16( i16* <ptr>, i16 <cmp>, i16 <val> )
5874 declare i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* <ptr>, i32 <cmp>, i32 <val> )
5875 declare i64 @llvm.atomic.cmp.swap.i64.p0i64( i64* <ptr>, i64 <cmp>, i64 <val> )
5880 This loads a value in memory and compares it to a given value. If they are
5881 equal, it stores a new value into the memory.
5885 The <tt>llvm.atomic.cmp.swap</tt> intrinsic takes three arguments. The result as
5886 well as both <tt>cmp</tt> and <tt>val</tt> must be integer values with the
5887 same bit width. The <tt>ptr</tt> argument must be a pointer to a value of
5888 this integer type. While any bit width integer may be used, targets may only
5889 lower representations they support in hardware.
5894 This entire intrinsic must be executed atomically. It first loads the value
5895 in memory pointed to by <tt>ptr</tt> and compares it with the value
5896 <tt>cmp</tt>. If they are equal, <tt>val</tt> is stored into the memory. The
5897 loaded value is yielded in all cases. This provides the equivalent of an
5898 atomic compare-and-swap operation within the SSA framework.
5906 %val1 = add i32 4, 4
5907 %result1 = call i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* %ptr, i32 4, %val1 )
5908 <i>; yields {i32}:result1 = 4</i>
5909 %stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
5910 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
5912 %val2 = add i32 1, 1
5913 %result2 = call i32 @llvm.atomic.cmp.swap.i32.p0i32( i32* %ptr, i32 5, %val2 )
5914 <i>; yields {i32}:result2 = 8</i>
5915 %stored2 = icmp eq i32 %result2, 5 <i>; yields {i1}:stored2 = false</i>
5917 %memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 8</i>
5921 <!-- _______________________________________________________________________ -->
5922 <div class="doc_subsubsection">
5923 <a name="int_atomic_swap">'<tt>llvm.atomic.swap.*</tt>' Intrinsic</a>
5925 <div class="doc_text">
5929 This is an overloaded intrinsic. You can use <tt>llvm.atomic.swap</tt> on any
5930 integer bit width. Not all targets support all bit widths however.</p>
5932 declare i8 @llvm.atomic.swap.i8.p0i8( i8* <ptr>, i8 <val> )
5933 declare i16 @llvm.atomic.swap.i16.p0i16( i16* <ptr>, i16 <val> )
5934 declare i32 @llvm.atomic.swap.i32.p0i32( i32* <ptr>, i32 <val> )
5935 declare i64 @llvm.atomic.swap.i64.p0i64( i64* <ptr>, i64 <val> )
5940 This intrinsic loads the value stored in memory at <tt>ptr</tt> and yields
5941 the value from memory. It then stores the value in <tt>val</tt> in the memory
5947 The <tt>llvm.atomic.swap</tt> intrinsic takes two arguments. Both the
5948 <tt>val</tt> argument and the result must be integers of the same bit width.
5949 The first argument, <tt>ptr</tt>, must be a pointer to a value of this
5950 integer type. The targets may only lower integer representations they
5955 This intrinsic loads the value pointed to by <tt>ptr</tt>, yields it, and
5956 stores <tt>val</tt> back into <tt>ptr</tt> atomically. This provides the
5957 equivalent of an atomic swap operation within the SSA framework.
5965 %val1 = add i32 4, 4
5966 %result1 = call i32 @llvm.atomic.swap.i32.p0i32( i32* %ptr, i32 %val1 )
5967 <i>; yields {i32}:result1 = 4</i>
5968 %stored1 = icmp eq i32 %result1, 4 <i>; yields {i1}:stored1 = true</i>
5969 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 8</i>
5971 %val2 = add i32 1, 1
5972 %result2 = call i32 @llvm.atomic.swap.i32.p0i32( i32* %ptr, i32 %val2 )
5973 <i>; yields {i32}:result2 = 8</i>
5975 %stored2 = icmp eq i32 %result2, 8 <i>; yields {i1}:stored2 = true</i>
5976 %memval2 = load i32* %ptr <i>; yields {i32}:memval2 = 2</i>
5980 <!-- _______________________________________________________________________ -->
5981 <div class="doc_subsubsection">
5982 <a name="int_atomic_load_add">'<tt>llvm.atomic.load.add.*</tt>' Intrinsic</a>
5985 <div class="doc_text">
5988 This is an overloaded intrinsic. You can use <tt>llvm.atomic.load.add</tt> on any
5989 integer bit width. Not all targets support all bit widths however.</p>
5991 declare i8 @llvm.atomic.load.add.i8..p0i8( i8* <ptr>, i8 <delta> )
5992 declare i16 @llvm.atomic.load.add.i16..p0i16( i16* <ptr>, i16 <delta> )
5993 declare i32 @llvm.atomic.load.add.i32..p0i32( i32* <ptr>, i32 <delta> )
5994 declare i64 @llvm.atomic.load.add.i64..p0i64( i64* <ptr>, i64 <delta> )
5999 This intrinsic adds <tt>delta</tt> to the value stored in memory at
6000 <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
6005 The intrinsic takes two arguments, the first a pointer to an integer value
6006 and the second an integer value. The result is also an integer value. These
6007 integer types can have any bit width, but they must all have the same bit
6008 width. The targets may only lower integer representations they support.
6012 This intrinsic does a series of operations atomically. It first loads the
6013 value stored at <tt>ptr</tt>. It then adds <tt>delta</tt>, stores the result
6014 to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.
6021 %result1 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 4 )
6022 <i>; yields {i32}:result1 = 4</i>
6023 %result2 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 2 )
6024 <i>; yields {i32}:result2 = 8</i>
6025 %result3 = call i32 @llvm.atomic.load.add.i32.p0i32( i32* %ptr, i32 5 )
6026 <i>; yields {i32}:result3 = 10</i>
6027 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 15</i>
6031 <!-- _______________________________________________________________________ -->
6032 <div class="doc_subsubsection">
6033 <a name="int_atomic_load_sub">'<tt>llvm.atomic.load.sub.*</tt>' Intrinsic</a>
6036 <div class="doc_text">
6039 This is an overloaded intrinsic. You can use <tt>llvm.atomic.load.sub</tt> on
6040 any integer bit width and for different address spaces. Not all targets
6041 support all bit widths however.</p>
6043 declare i8 @llvm.atomic.load.sub.i8.p0i32( i8* <ptr>, i8 <delta> )
6044 declare i16 @llvm.atomic.load.sub.i16.p0i32( i16* <ptr>, i16 <delta> )
6045 declare i32 @llvm.atomic.load.sub.i32.p0i32( i32* <ptr>, i32 <delta> )
6046 declare i64 @llvm.atomic.load.sub.i64.p0i32( i64* <ptr>, i64 <delta> )
6051 This intrinsic subtracts <tt>delta</tt> to the value stored in memory at
6052 <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
6057 The intrinsic takes two arguments, the first a pointer to an integer value
6058 and the second an integer value. The result is also an integer value. These
6059 integer types can have any bit width, but they must all have the same bit
6060 width. The targets may only lower integer representations they support.
6064 This intrinsic does a series of operations atomically. It first loads the
6065 value stored at <tt>ptr</tt>. It then subtracts <tt>delta</tt>, stores the
6066 result to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.
6073 %result1 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 4 )
6074 <i>; yields {i32}:result1 = 8</i>
6075 %result2 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 2 )
6076 <i>; yields {i32}:result2 = 4</i>
6077 %result3 = call i32 @llvm.atomic.load.sub.i32.p0i32( i32* %ptr, i32 5 )
6078 <i>; yields {i32}:result3 = 2</i>
6079 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = -3</i>
6083 <!-- _______________________________________________________________________ -->
6084 <div class="doc_subsubsection">
6085 <a name="int_atomic_load_and">'<tt>llvm.atomic.load.and.*</tt>' Intrinsic</a><br>
6086 <a name="int_atomic_load_nand">'<tt>llvm.atomic.load.nand.*</tt>' Intrinsic</a><br>
6087 <a name="int_atomic_load_or">'<tt>llvm.atomic.load.or.*</tt>' Intrinsic</a><br>
6088 <a name="int_atomic_load_xor">'<tt>llvm.atomic.load.xor.*</tt>' Intrinsic</a><br>
6091 <div class="doc_text">
6094 These are overloaded intrinsics. You can use <tt>llvm.atomic.load_and</tt>,
6095 <tt>llvm.atomic.load_nand</tt>, <tt>llvm.atomic.load_or</tt>, and
6096 <tt>llvm.atomic.load_xor</tt> on any integer bit width and for different
6097 address spaces. Not all targets support all bit widths however.</p>
6099 declare i8 @llvm.atomic.load.and.i8.p0i8( i8* <ptr>, i8 <delta> )
6100 declare i16 @llvm.atomic.load.and.i16.p0i16( i16* <ptr>, i16 <delta> )
6101 declare i32 @llvm.atomic.load.and.i32.p0i32( i32* <ptr>, i32 <delta> )
6102 declare i64 @llvm.atomic.load.and.i64.p0i64( i64* <ptr>, i64 <delta> )
6107 declare i8 @llvm.atomic.load.or.i8.p0i8( i8* <ptr>, i8 <delta> )
6108 declare i16 @llvm.atomic.load.or.i16.p0i16( i16* <ptr>, i16 <delta> )
6109 declare i32 @llvm.atomic.load.or.i32.p0i32( i32* <ptr>, i32 <delta> )
6110 declare i64 @llvm.atomic.load.or.i64.p0i64( i64* <ptr>, i64 <delta> )
6115 declare i8 @llvm.atomic.load.nand.i8.p0i32( i8* <ptr>, i8 <delta> )
6116 declare i16 @llvm.atomic.load.nand.i16.p0i32( i16* <ptr>, i16 <delta> )
6117 declare i32 @llvm.atomic.load.nand.i32.p0i32( i32* <ptr>, i32 <delta> )
6118 declare i64 @llvm.atomic.load.nand.i64.p0i32( i64* <ptr>, i64 <delta> )
6123 declare i8 @llvm.atomic.load.xor.i8.p0i32( i8* <ptr>, i8 <delta> )
6124 declare i16 @llvm.atomic.load.xor.i16.p0i32( i16* <ptr>, i16 <delta> )
6125 declare i32 @llvm.atomic.load.xor.i32.p0i32( i32* <ptr>, i32 <delta> )
6126 declare i64 @llvm.atomic.load.xor.i64.p0i32( i64* <ptr>, i64 <delta> )
6131 These intrinsics bitwise the operation (and, nand, or, xor) <tt>delta</tt> to
6132 the value stored in memory at <tt>ptr</tt>. It yields the original value
6138 These intrinsics take two arguments, the first a pointer to an integer value
6139 and the second an integer value. The result is also an integer value. These
6140 integer types can have any bit width, but they must all have the same bit
6141 width. The targets may only lower integer representations they support.
6145 These intrinsics does a series of operations atomically. They first load the
6146 value stored at <tt>ptr</tt>. They then do the bitwise operation
6147 <tt>delta</tt>, store the result to <tt>ptr</tt>. They yield the original
6148 value stored at <tt>ptr</tt>.
6154 store i32 0x0F0F, %ptr
6155 %result0 = call i32 @llvm.atomic.load.nand.i32.p0i32( i32* %ptr, i32 0xFF )
6156 <i>; yields {i32}:result0 = 0x0F0F</i>
6157 %result1 = call i32 @llvm.atomic.load.and.i32.p0i32( i32* %ptr, i32 0xFF )
6158 <i>; yields {i32}:result1 = 0xFFFFFFF0</i>
6159 %result2 = call i32 @llvm.atomic.load.or.i32.p0i32( i32* %ptr, i32 0F )
6160 <i>; yields {i32}:result2 = 0xF0</i>
6161 %result3 = call i32 @llvm.atomic.load.xor.i32.p0i32( i32* %ptr, i32 0F )
6162 <i>; yields {i32}:result3 = FF</i>
6163 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = F0</i>
6168 <!-- _______________________________________________________________________ -->
6169 <div class="doc_subsubsection">
6170 <a name="int_atomic_load_max">'<tt>llvm.atomic.load.max.*</tt>' Intrinsic</a><br>
6171 <a name="int_atomic_load_min">'<tt>llvm.atomic.load.min.*</tt>' Intrinsic</a><br>
6172 <a name="int_atomic_load_umax">'<tt>llvm.atomic.load.umax.*</tt>' Intrinsic</a><br>
6173 <a name="int_atomic_load_umin">'<tt>llvm.atomic.load.umin.*</tt>' Intrinsic</a><br>
6176 <div class="doc_text">
6179 These are overloaded intrinsics. You can use <tt>llvm.atomic.load_max</tt>,
6180 <tt>llvm.atomic.load_min</tt>, <tt>llvm.atomic.load_umax</tt>, and
6181 <tt>llvm.atomic.load_umin</tt> on any integer bit width and for different
6182 address spaces. Not all targets
6183 support all bit widths however.</p>
6185 declare i8 @llvm.atomic.load.max.i8.p0i8( i8* <ptr>, i8 <delta> )
6186 declare i16 @llvm.atomic.load.max.i16.p0i16( i16* <ptr>, i16 <delta> )
6187 declare i32 @llvm.atomic.load.max.i32.p0i32( i32* <ptr>, i32 <delta> )
6188 declare i64 @llvm.atomic.load.max.i64.p0i64( i64* <ptr>, i64 <delta> )
6193 declare i8 @llvm.atomic.load.min.i8.p0i8( i8* <ptr>, i8 <delta> )
6194 declare i16 @llvm.atomic.load.min.i16.p0i16( i16* <ptr>, i16 <delta> )
6195 declare i32 @llvm.atomic.load.min.i32..p0i32( i32* <ptr>, i32 <delta> )
6196 declare i64 @llvm.atomic.load.min.i64..p0i64( i64* <ptr>, i64 <delta> )
6201 declare i8 @llvm.atomic.load.umax.i8.p0i8( i8* <ptr>, i8 <delta> )
6202 declare i16 @llvm.atomic.load.umax.i16.p0i16( i16* <ptr>, i16 <delta> )
6203 declare i32 @llvm.atomic.load.umax.i32.p0i32( i32* <ptr>, i32 <delta> )
6204 declare i64 @llvm.atomic.load.umax.i64.p0i64( i64* <ptr>, i64 <delta> )
6209 declare i8 @llvm.atomic.load.umin.i8..p0i8( i8* <ptr>, i8 <delta> )
6210 declare i16 @llvm.atomic.load.umin.i16.p0i16( i16* <ptr>, i16 <delta> )
6211 declare i32 @llvm.atomic.load.umin.i32..p0i32( i32* <ptr>, i32 <delta> )
6212 declare i64 @llvm.atomic.load.umin.i64..p0i64( i64* <ptr>, i64 <delta> )
6217 These intrinsics takes the signed or unsigned minimum or maximum of
6218 <tt>delta</tt> and the value stored in memory at <tt>ptr</tt>. It yields the
6219 original value at <tt>ptr</tt>.
6224 These intrinsics take two arguments, the first a pointer to an integer value
6225 and the second an integer value. The result is also an integer value. These
6226 integer types can have any bit width, but they must all have the same bit
6227 width. The targets may only lower integer representations they support.
6231 These intrinsics does a series of operations atomically. They first load the
6232 value stored at <tt>ptr</tt>. They then do the signed or unsigned min or max
6233 <tt>delta</tt> and the value, store the result to <tt>ptr</tt>. They yield
6234 the original value stored at <tt>ptr</tt>.
6241 %result0 = call i32 @llvm.atomic.load.min.i32.p0i32( i32* %ptr, i32 -2 )
6242 <i>; yields {i32}:result0 = 7</i>
6243 %result1 = call i32 @llvm.atomic.load.max.i32.p0i32( i32* %ptr, i32 8 )
6244 <i>; yields {i32}:result1 = -2</i>
6245 %result2 = call i32 @llvm.atomic.load.umin.i32.p0i32( i32* %ptr, i32 10 )
6246 <i>; yields {i32}:result2 = 8</i>
6247 %result3 = call i32 @llvm.atomic.load.umax.i32.p0i32( i32* %ptr, i32 30 )
6248 <i>; yields {i32}:result3 = 8</i>
6249 %memval1 = load i32* %ptr <i>; yields {i32}:memval1 = 30</i>
6253 <!-- ======================================================================= -->
6254 <div class="doc_subsection">
6255 <a name="int_general">General Intrinsics</a>
6258 <div class="doc_text">
6259 <p> This class of intrinsics is designed to be generic and has
6260 no specific purpose. </p>
6263 <!-- _______________________________________________________________________ -->
6264 <div class="doc_subsubsection">
6265 <a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
6268 <div class="doc_text">
6272 declare void @llvm.var.annotation(i8* <val>, i8* <str>, i8* <str>, i32 <int> )
6278 The '<tt>llvm.var.annotation</tt>' intrinsic
6284 The first argument is a pointer to a value, the second is a pointer to a
6285 global string, the third is a pointer to a global string which is the source
6286 file name, and the last argument is the line number.
6292 This intrinsic allows annotation of local variables with arbitrary strings.
6293 This can be useful for special purpose optimizations that want to look for these
6294 annotations. These have no other defined use, they are ignored by code
6295 generation and optimization.
6299 <!-- _______________________________________________________________________ -->
6300 <div class="doc_subsubsection">
6301 <a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
6304 <div class="doc_text">
6307 <p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
6308 any integer bit width.
6311 declare i8 @llvm.annotation.i8(i8 <val>, i8* <str>, i8* <str>, i32 <int> )
6312 declare i16 @llvm.annotation.i16(i16 <val>, i8* <str>, i8* <str>, i32 <int> )
6313 declare i32 @llvm.annotation.i32(i32 <val>, i8* <str>, i8* <str>, i32 <int> )
6314 declare i64 @llvm.annotation.i64(i64 <val>, i8* <str>, i8* <str>, i32 <int> )
6315 declare i256 @llvm.annotation.i256(i256 <val>, i8* <str>, i8* <str>, i32 <int> )
6321 The '<tt>llvm.annotation</tt>' intrinsic.
6327 The first argument is an integer value (result of some expression),
6328 the second is a pointer to a global string, the third is a pointer to a global
6329 string which is the source file name, and the last argument is the line number.
6330 It returns the value of the first argument.
6336 This intrinsic allows annotations to be put on arbitrary expressions
6337 with arbitrary strings. This can be useful for special purpose optimizations
6338 that want to look for these annotations. These have no other defined use, they
6339 are ignored by code generation and optimization.
6342 <!-- _______________________________________________________________________ -->
6343 <div class="doc_subsubsection">
6344 <a name="int_trap">'<tt>llvm.trap</tt>' Intrinsic</a>
6347 <div class="doc_text">
6351 declare void @llvm.trap()
6357 The '<tt>llvm.trap</tt>' intrinsic
6369 This intrinsics is lowered to the target dependent trap instruction. If the
6370 target does not have a trap instruction, this intrinsic will be lowered to the
6371 call of the abort() function.
6375 <!-- *********************************************************************** -->
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