The LLVM representation aims to be a light-weight and low-level +
The LLVM representation aims to be light-weight and low-level while being expressive, typed, and extensible at the same time. It aims to be a "universal IR" of sorts, by being at a low enough level that high-level ideas may be cleanly mapped to it (similar to how @@ -206,13 +250,13 @@ accepts and what is considered 'well formed'. For example, the following instruction is syntactically okay, but not well formed:
- %x = add int 1, %x + %x = add i32 1, %x
...because the definition of %x does not dominate all of its uses. The LLVM infrastructure provides a verification pass that may be used to verify that an LLVM module is well formed. This pass is -automatically run by the parser after parsing input assembly, and by +automatically run by the parser after parsing input assembly and by the optimizer before it outputs bytecode. The violations pointed out by the verifier pass indicate bugs in transformation passes or input to the parser.
@@ -233,7 +277,7 @@ purposes: For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual regular expression used is '%[a-zA-Z$._][a-zA-Z$._0-9]*'. Identifiers which require other characters in their names can be surrounded - with quotes. In this way, anything except a " character can be used + with quotes. In this way, anything except a " character can be used in a name.Reserved words in LLVM are very similar to reserved words in other -languages. There are keywords for different opcodes ('add', 'cast', 'ret', etc...), for primitive type names ('void', 'uint', etc...), +languages. There are keywords for different opcodes +('add', + 'bitcast', + 'ret', etc...), for primitive type names ('void', 'i32', etc...), and others. These reserved words cannot conflict with variable names, because none of them start with a '%' character.
@@ -263,21 +308,21 @@ none of them start with a '%' character.The easy way:
- %result = mul uint %X, 8 + %result = mul i32 %X, 8
After strength reduction:
- %result = shl uint %X, ubyte 3 + %result = shl i32 %X, i8 3
And the hard way:
- add uint %X, %X ; yields {uint}:%0 - add uint %0, %0 ; yields {uint}:%1 - %result = add uint %1, %1 + add i32 %X, %X ; yields {i32}:%0 + add i32 %0, %0 ; yields {i32}:%1 + %result = add i32 %1, %1
This last way of multiplying %X by 8 illustrates several @@ -295,7 +340,7 @@ important lexical features of LLVM:
-...and it also show a convention that we follow in this document. When +
...and it also shows a convention that we follow in this document. When demonstrating instructions, we will follow an instruction with a comment that defines the type and name of value produced. Comments are shown in italic text.
@@ -321,22 +366,25 @@ symbol table entries. Here is an example of the "hello world" module:; Declare the string constant as a global constant... %.LC0 = internal constant [13 x sbyte] c"hello world\0A\00" ; [13 x sbyte]* + href="#globalvars">constant [13 x i8 ] c"hello world\0A\00" ; [13 x i8 ]* ; External declaration of the puts function -declare int %puts(sbyte*) ; int(sbyte*)* +declare i32 %puts(i8 *) ; i32(i8 *)* + +; Global variable / Function body section separator +implementation ; Definition of main function -int %main() { ; int()* - ; Convert [13x sbyte]* to sbyte *... +define i32 %main() { ; i32()* + ; Convert [13x i8 ]* to i8 *... %cast210 = getelementptr [13 x sbyte]* %.LC0, long 0, long 0 ; sbyte* + href="#i_getelementptr">getelementptr [13 x i8 ]* %.LC0, i64 0, i64 0 ; i8 * ; Call puts function to write out the string to stdout... call int %puts(sbyte* %cast210) ; int + href="#i_call">call i32 %puts(i8 * %cast210) ; i32 ret int 0+ href="#i_ret">ret i32 0
}
This example is made up of a global variable named ".LC0", an external declaration of the "puts" @@ -349,6 +397,13 @@ represented by a pointer to a memory location (in this case, a pointer to an array of char, and a pointer to a function), and have one of the following linkage types.
+Due to a limitation in the current LLVM assembly parser (it is limited by +one-token lookahead), modules are split into two pieces by the "implementation" +keyword. Global variable prototypes and definitions must occur before the +keyword, and function definitions must occur after it. Function prototypes may +occur either before or after it. In the future, the implementation keyword may +become a noop, if the parser gets smarter.
+ @@ -371,23 +426,26 @@ All Global Variables and Functions have one of the following types of linkage: an internal global value may cause the internal to be renamed as necessary to avoid collisions. Because the symbol is internal to the module, all references can be updated. This corresponds to the notion of the - 'static' keyword in C, or the idea of "anonymous namespaces" in C++. + 'static' keyword in C.+ The next two types of linkage are targeted for Microsoft Windows platform + only. They are designed to support importing (exporting) symbols from (to) + DLLs. +
+ +_imp__ and the function or variable name.
+ _imp__ and the function or variable
+ name.
+ For example, since the ".LC0"
+ For example, since the ".LC0"
variable is defined to be internal, if another module defined a ".LC0"
variable and was linked with this one, one of the two would be renamed,
preventing a collision. Since "main" and "puts" are
external (i.e., lacking any linkage declarations), they are accessible
-outside of the current module. It is illegal for a function declaration
-to have any linkage type other than "externally visible".
It is illegal for a function declaration +to have any linkage type other than "externally visible", dllimport, +or extern_weak.
+ + + + + + +LLVM functions, calls +and invokes can all have an optional calling convention +specified for the call. The calling convention of any pair of dynamic +caller/callee must match, or the behavior of the program is undefined. The +following calling conventions are supported by LLVM, and more may be added in +the future:
+ +More calling conventions can be added/defined on an as-needed basis, to +support pascal conventions or any other well-known target-independent +convention.
+ ++All Global Variables and Functions have one of the following visibility styles: +
+ +Global variables define regions of memory allocated at compilation time -instead of run-time. Global variables may optionally be initialized. A -variable may be defined as a global "constant", which indicates that the +instead of run-time. Global variables may optionally be initialized, may have +an explicit section to be placed in, and may +have an optional explicit alignment specified. A +variable may be defined as a global "constant," which indicates that the contents of the variable will never be modified (enabling better optimization, allowing the global data to be placed in the read-only section of an executable, etc). Note that variables that need runtime initialization -cannot be marked "constant", as there is a store to the variable.
+cannot be marked "constant" as there is a store to the variable.LLVM explicitly allows declarations of global variables to be marked @@ -447,6 +633,22 @@ variables always define a pointer to their "content" type because they describe a region of memory, and all memory objects in LLVM are accessed through pointers.
+LLVM allows an explicit section to be specified for globals. If the target +supports it, it will emit globals to the section specified.
+ +An explicit alignment may be specified for a global. If not present, or if +the alignment is set to zero, the alignment of the global is set by the target +to whatever it feels convenient. If an explicit alignment is specified, the +global is forced to have at least that much alignment. All alignments must be +a power of 2.
+ +For example, the following defines a global with an initializer, section, + and alignment:
+ ++ %G = constant float 1.0, section "foo", align 4 ++
LLVM function definitions are composed of a (possibly empty) argument list, -an opening curly brace, a list of basic blocks, and a closing curly brace. LLVM -function declarations are defined with the "declare" keyword, a -function name, and a function signature.
+LLVM function definitions consist of the "define" keyord, +an optional linkage type, an optional +visibility style, an optional +calling convention, a return type, an optional +parameter attribute for the return type, a function +name, a (possibly empty) argument list (each with optional +parameter attributes), an optional section, an +optional alignment, an opening curly brace, a list of basic blocks, and a +closing curly brace. + +LLVM function declarations consist of the "declare" keyword, an +optional linkage type, an optional +visibility style, an optional +calling convention, a return type, an optional +parameter attribute for the return type, a function +name, a possibly empty list of arguments, and an optional alignment.
A function definition contains a list of basic blocks, forming the CFG for the function. Each basic block may optionally start with a label (giving the @@ -468,7 +682,7 @@ basic block a symbol table entry), contains a list of instructions, and ends with a terminator instruction (such as a branch or function return).
-The first basic block in program is special in two ways: it is immediately +
The first basic block in a program is special in two ways: it is immediately executed on entrance to the function, and it is not allowed to have predecessor basic blocks (i.e. there can not be any branches to the entry block of a function). Because the block can have no predecessors, it also cannot have any @@ -476,12 +690,172 @@ function). Because the block can have no predecessors, it also cannot have any
LLVM functions are identified by their name and type signature. Hence, two functions with the same name but different parameter lists or return values are -considered different functions, and LLVM will resolves references to each +considered different functions, and LLVM will resolve references to each appropriately.
+LLVM allows an explicit section to be specified for functions. If the target +supports it, it will emit functions to the section specified.
+ +An explicit alignment may be specified for a function. If not present, or if +the alignment is set to zero, the alignment of the function is set by the target +to whatever it feels convenient. If an explicit alignment is specified, the +function is forced to have at least that much alignment. All alignments must be +a power of 2.
+ +The return type and each parameter of a function type may have a set of + parameter attributes associated with them. Parameter attributes are + used to communicate additional information about the result or parameters of + a function. Parameter attributes are considered to be part of the function + type so two functions types that differ only by the parameter attributes + are different function types.
+ +Parameter attributes are simple keywords that follow the type specified. If + multiple parameter attributes are needed, they are space separated. For + example:
+ %someFunc = i16 (i8 sext %someParam) zext + %someFunc = i16 (i8 zext %someParam) zext+
Note that the two function types above are unique because the parameter has + a different attribute (sext in the first one, zext in the second). Also note + that the attribute for the function result (zext) comes immediately after the + argument list.
+ +Currently, only the following parameter attributes are defined:
++Modules may contain "module-level inline asm" blocks, which corresponds to the +GCC "file scope inline asm" blocks. These blocks are internally concatenated by +LLVM and treated as a single unit, but may be separated in the .ll file if +desired. The syntax is very simple: +
+ ++ module asm "inline asm code goes here" + module asm "more can go here" +
The strings can contain any character by escaping non-printable characters. + The escape sequence used is simply "\xx" where "xx" is the two digit hex code + for the number. +
+ ++ The inline asm code is simply printed to the machine code .s file when + assembly code is generated. +
A module may specify a target specific data layout string that specifies how
+data is to be laid out in memory. The syntax for the data layout is simply:
+
target datalayout = "layout specification" ++The layout specification consists of a list of specifications separated +by the minus sign character ('-'). Each specification starts with a letter +and may include other information after the letter to define some aspect of the +data layout. The specifications accepted are as follows: +
When constructing the data layout for a given target, LLVM starts with a +default set of specifications which are then (possibly) overriden by the +specifications in the datalayout keyword. The default specifications +are given in this list:
+When llvm is determining the alignment for a given type, it uses the +following rules: +
The primitive types are the fundamental building blocks of the LLVM -system. The current set of primitive types are as follows:
+system. The current set of primitive types is as follows:| Type | Description |
|---|---|
| void | No value |
| ubyte | Unsigned 8 bit value |
| ushort | Unsigned 16 bit value |
| uint | Unsigned 32 bit value |
| ulong | Unsigned 64 bit value |
| float | 32 bit floating point value |
| i8 | 8-bit value |
| i32 | 32-bit value |
| float | 32-bit floating point value |
| label | Branch destination |
| Type | Description |
|---|---|
| bool | True or False value |
| sbyte | Signed 8 bit value |
| short | Signed 16 bit value |
| int | Signed 32 bit value |
| long | Signed 64 bit value |
| double | 64 bit floating point value |
| i1 | True or False value |
| i16 | 16-bit value |
| i64 | 64-bit value |
| double | 64-bit floating point value |
| Classification | Types | |
|---|---|---|
| signed | -sbyte, short, int, long, float, double | -|
| unsigned | -ubyte, ushort, uint, ulong | -|
| integer | -ubyte, sbyte, ushort, short, uint, int, ulong, long | -|
| integral | -bool, ubyte, sbyte, ushort, short, uint, int, ulong, long - | +i1, i8, i16, i32, i64 |
| floating point | @@ -571,9 +928,9 @@ classifications:||
| first class | -bool, ubyte, sbyte, ushort, short, uint, int, ulong, long, - float, double, pointer, - packed |
+ i1, i8, i16, i32, i64, float, double, + pointer,vector + |
The number of elements is a constant integer value, elementtype may +
The number of elements is a constant integer value; elementtype may be any type with a size.
|
- [40 x int ] - [41 x int ] - [40 x uint] + [40 x i32 ] + [41 x i32 ] + [40 x i8] |
- Array of 40 integer values. - Array of 41 integer values. - Array of 40 unsigned integer values. + Array of 40 32-bit integer values. + Array of 41 32-bit integer values. + Array of 40 8-bit integer values. |
|
- [3 x [4 x int]] + [3 x [4 x i32]] [12 x [10 x float]] - [2 x [3 x [4 x uint]]] + [2 x [3 x [4 x i16]]] |
- 3x4 array integer values. + 3x4 array of 32-bit integer values. 12x10 array of single precision floating point values. - 2x3x4 array of unsigned integer values. + 2x3x4 array of 16-bit integer values. |
Note that 'variable sized arrays' can be implemented in LLVM with a zero +length array. Normally, accesses past the end of an array are undefined in +LLVM (e.g. it is illegal to access the 5th element of a 3 element array). +As a special case, however, zero length arrays are recognized to be variable +length. This allows implementation of 'pascal style arrays' with the LLVM +type "{ i32, [0 x float]}", for example.
+<returntype> (<parameter list>)-
Where '<parameter list>' is a comma-separated list of type +
...where '<parameter list>' is a comma-separated list of type specifiers. Optionally, the parameter list may include a type ..., which indicates that the function takes a variable number of arguments. Variable argument functions can access their arguments with the Examples:
|
- int (int) - float (int, int *) * - int (sbyte *, ...) + | i32 (i32) | +function taking an i32, returning an i32 | -
- function taking an int, returning an int - Pointer to a function that takes an - int and a pointer to int, - returning float. - A vararg function that takes at least one pointer - to sbyte (signed char in C), which returns an integer. This is - the signature for printf in LLVM. + |
| float (i16 sext, i32 *) * + | +Pointer to a function that takes + an i16 that should be sign extended and a + pointer to i32, returning + float. + | +||
| i32 (i8*, ...) | +A vararg function that takes at least one + pointer to i8 (char in C), + which returns an integer. This is the signature for printf in + LLVM. |
|
- { int, int, int } - { float, int (int) * } + { i32, i32, i32 } + { float, i32 (i32) * } + |
+
+ a triple of three i32 values + A pair, where the first element is a float and the second element + is a pointer to a function + that takes an i32, returning an i32. + |
+
The packed structure type is used to represent a collection of data members +together in memory. There is no padding between fields. Further, the alignment +of a packed structure is 1 byte. The elements of a packed structure may +be any type that has a size.
+Structures are accessed using 'load +and 'store' by getting a pointer to a +field with the 'getelementptr' +instruction.
+ < { <type list> } >
+|
+ < { i32, i32, i32 } > + < { float, i32 (i32) * } > |
- a triple of three int values + a triple of three i32 values A pair, where the first element is a float and the second element is a pointer to a function - that takes an int, returning an int. + that takes an i32, returning an i32. |
|
- [4x int]* - int (int *) * + [4x i32]* + i32 (i32 *) * |
A pointer to array of
- four int values + four i32 values A pointer to a function that takes an int*, returning an - int. + href="#t_function">function that takes an i32*, returning an + i32. |
A packed type is a simple derived type that represents a vector -of elements. Packed types are used when multiple primitive data + +
A vector type is a simple derived type that represents a vector +of elements. Vector types are used when multiple primitive data are operated in parallel using a single instruction (SIMD). -A packed type requires a size (number of -elements) and an underlying primitive data type. Packed types are +A vector type requires a size (number of +elements) and an underlying primitive data type. Vectors must have a power +of two length (1, 2, 4, 8, 16 ...). Vector types are considered first class.
+< <# elements> x <elementtype> >-
The number of elements is a constant integer value, elementtype may -be any integral or floating point type.
+ ++ < <# elements> x <elementtype> > ++ +
The number of elements is a constant integer value; elementtype may +be any integer or floating point type.
+|
- <4 x int> + <4 x i32> <8 x float> - <2 x uint> + <2 x i64> + |
+
+ Vector of 4 32-bit integer values. + Vector of 8 floating-point values. + Vector of 2 64-bit integer values. + |
+
Opaque types are used to represent unknown types in the system. This +corresponds (for example) to the C notion of a foward declared structure type. +In LLVM, opaque types can eventually be resolved to any type (not just a +structure type).
+ ++ opaque ++ +
| + opaque |
- Packed vector of 4 integer values. - Packed vector of 8 floating-point values. - Packed vector of 2 unsigned integer values. + An opaque type. |
Aggregate constants arise from aggregation of simple constants +and smaller aggregate constants.
- %X = global int 17 - %Y = global int 42 - %Z = global [2 x int*] [ int* %X, int* %Y ] + %X = global i32 17 + %Y = global i32 42 + %Z = global [2 x i32*] [ i32* %X, i32* %Y ]
The string 'undef' is recognized as a type-less constant that has - no specific value. Undefined values may be of any type, and be used anywhere + no specific value. Undefined values may be of any type and be used anywhere a constant is permitted.
Undefined values indicate to the compiler that the program is well defined @@ -923,14 +1368,71 @@ file:
Constant expressions are used to allow expressions involving other constants to be used as constants. Constant expressions may be of any first class type, and may involve any LLVM operation +href="#t_firstclass">first class type and may involve any LLVM operation that does not have side effects (e.g. load and call are not supported). The following is the syntax for constant expressions:
+LLVM supports inline assembler expressions (as opposed to +Module-Level Inline Assembly) through the use of a special value. This +value represents the inline assembler as a string (containing the instructions +to emit), a list of operand constraints (stored as a string), and a flag that +indicates whether or not the inline asm expression has side effects. An example +inline assembler expression is: +
+ ++ i32 (i32) asm "bswap $0", "=r,r" ++ +
+Inline assembler expressions may only be used as the callee operand of +a call instruction. Thus, typically we have: +
+ ++ %X = call i32 asm "bswap $0", "=r,r"(i32 %Y) ++ +
+Inline asms with side effects not visible in the constraint list must be marked +as having side effects. This is done through the use of the +'sideeffect' keyword, like so: +
+ ++ call void asm sideeffect "eieio", ""() ++ +
TODO: The format of the asm and constraints string still need to be +documented here. Constraints on what can be done (e.g. duplication, moving, etc +need to be documented). +
+ +The LLVM instruction set consists of several different classifications of instructions: terminator -instructions, binary instructions, , binary instructions, +bitwise binary instructions, memory instructions, and other instructions.
@@ -994,7 +1574,7 @@ InstructionThe 'ret' instruction is used to return control flow (and a -value) from a function, back to the caller.
+value) from a function back to the caller.There are two forms of the 'ret' instruction: one that returns a value and then causes control flow, and one that just causes control flow to occur.
@@ -1010,11 +1590,11 @@ returns back to the calling function's context. If the caller is a "call" instruction, execution continues at the instruction after the call. If the caller was an "invoke" instruction, execution continues -at the beginning "normal" of the destination block. If the instruction +at the beginning of the "normal" destination block. If the instruction returns a value, that value shall set the call or invoke instruction's return value.ret int 5 ; Return an integer value of 5 +ret i32 5 ; Return an integer value of 5 ret void ; Return from a void function@@ -1022,7 +1602,7 @@ return value.Syntax:
-br bool <cond>, label <iftrue>, label <iffalse>
br label <dest> ; Unconditional branch +br i1 <cond>, label <iftrue>, label <iffalse>
br label <dest> ; Unconditional branchOverview:
The 'br' instruction is used to cause control flow to @@ -1031,17 +1611,17 @@ two forms of this instruction, corresponding to a conditional branch and an unconditional branch.
Arguments:
The conditional branch form of the 'br' instruction takes a -single 'bool' value and two 'label' values. The -unconditional form of the 'br' instruction takes a single 'label' -value as a target.
+single 'i1' value and two 'label' values. The +unconditional form of the 'br' instruction takes a single +'label' value as a target.Semantics:
-Upon execution of a conditional 'br' instruction, the 'bool' +
Upon execution of a conditional 'br' instruction, the 'i1' argument is evaluated. If the value is true, control flows to the 'iftrue' label argument. If "cond" is false, control flows to the 'iffalse' label argument.
Example:
-Test:+
%cond = seteq int %a, %b
br bool %cond, label %IfEqual, label %IfUnequal
IfEqual:
ret int 1
IfUnequal:
ret int 0Test:
%cond = icmp eq, i32 %a, %b
br i1 %cond, label %IfEqual, label %IfUnequal
IfEqual:
ret i32 1
IfUnequal:
ret i32 0@@ -1089,63 +1669,94 @@ branches or with a lookup table.+ - + +; Emulate a conditional br instruction - %Val = cast bool %value to int - switch int %Val, label %truedest [int 0, label %falsedest ] + %Val = zext i1 %value to i32 + switch i32 %Val, label %truedest [i32 0, label %falsedest ] ; Emulate an unconditional br instruction - switch uint 0, label %dest [ ] + switch i32 0, label %dest [ ] ; Implement a jump table: - switch uint %val, label %otherwise [ uint 0, label %onzero - uint 1, label %onone - uint 2, label %ontwo ] + switch i32 %val, label %otherwise [ i32 0, label %onzero + i32 1, label %onone + i32 2, label %ontwo ]+@@ -1211,7 +1822,7 @@ no-return function cannot be reached, and other facts.Syntax:
-<result> = invoke <ptr to function ty> %<function ptr val>(<function args>)+ +
to label <normal label> except label <exception label>+ <result> = invoke [cconv] <ptr to function ty> %<function ptr val>(<function args>) + to label <normal label> unwind label <exception label> ++Overview:
-The 'invoke' instruction causes control to transfer to a -specified function, with the possibility of control flow transfer to -either the 'normal' label label or the 'exception'label. -If the callee function returns with the "ret" -instruction, control flow will return to the "normal" label. If the -callee (or any indirect callees) returns with the "unwind" -instruction, control is interrupted, and continued at the dynamically -nearest "except" label.
+ +The 'invoke' instruction causes control to transfer to a specified +function, with the possibility of control flow transfer to either the +'normal' label or the +'exception' label. If the callee function returns with the +"ret" instruction, control flow will return to the +"normal" label. If the callee (or any indirect callees) returns with the "unwind" instruction, control is interrupted and +continued at the dynamically nearest "exception" label.
+Arguments:
+This instruction requires several arguments:
+-
+- 'ptr to function ty': shall be the signature of the -pointer to function value being invoked. In most cases, this is a -direct function invocation, but indirect invokes are just as -possible, branching off an arbitrary pointer to function value.
-- 'function ptr val': An LLVM value containing a pointer -to a function to be invoked.
-- 'function args': argument list whose types match the -function signature argument types. If the function signature indicates -the function accepts a variable number of arguments, the extra -arguments can be specified.
-- 'normal label': the label reached when the called -function executes a 'ret' instruction.
-- 'exception label': the label reached when a callee -returns with the unwind instruction.
+- + The optional "cconv" marker indicates which calling + convention the call should use. If none is specified, the call defaults + to using C calling conventions. +
+- 'ptr to function ty': shall be the signature of the pointer to + function value being invoked. In most cases, this is a direct function + invocation, but indirect invokes are just as possible, branching off + an arbitrary pointer to function value. +
+ +- 'function ptr val': An LLVM value containing a pointer to a + function to be invoked.
+ +- 'function args': argument list whose types match the function + signature argument types. If the function signature indicates the function + accepts a variable number of arguments, the extra arguments can be + specified.
+ +- 'normal label': the label reached when the called function + executes a 'ret' instruction.
+ +- 'exception label': the label reached when a callee returns with + the unwind instruction.
+Semantics:
+This instruction is designed to operate as a standard 'call' instruction in most regards. The -primary difference is that it establishes an association with a label, -which is used by the runtime library to unwind the stack.
-This instruction is used in languages with destructors to ensure -that proper cleanup is performed in the case of either a longjmp -or a thrown exception. Additionally, this is important for -implementation of 'catch' clauses in high-level languages that -support them.
+href="#i_call">call' instruction in most regards. The primary +difference is that it establishes an association with a label, which is used by +the runtime library to unwind the stack. + +This instruction is used in languages with destructors to ensure that proper +cleanup is performed in the case of either a longjmp or a thrown +exception. Additionally, this is important for implementation of +'catch' clauses in high-level languages that support them.
+Example:
-%retval = invoke int %Test(int 15)
to label %Continue
except label %TestCleanup ; {int}:retval set ++ %retval = invoke i32 %Test(i32 15) to label %Continue + unwind label %TestCleanup ; {i32}:retval set + %retval = invoke coldcc i32 %Test(i32 15) to label %Continue + unwind label %TestCleanup ; {i32}:retval setBinary operators are used to do most of the computation in a program. They require two operands, execute an operation on them, and produce a single value. The operands might represent -multiple data, as is the case with the packed data type. +multiple data, as is the case with the vector data type. The result value of a binary operator is not necessarily the same type as its operands.
There are several different binary operators:
@@ -1228,13 +1839,13 @@ InstructionArguments:
The two arguments to the 'add' instruction must be either integer or floating point values. - This instruction can also take packed versions of the values. + This instruction can also take vector versions of the values. Both arguments must have identical types.
Semantics:
The value produced is the integer or floating point sum of the two operands.
Example:
-<result> = add int 4, %var ; yields {int}:result = 4 + %var +<result> = add i32 4, %var ; yields {i32}:result = 4 + %var@@ -1253,14 +1864,14 @@ instruction present in most other intermediate representations.The two arguments to the 'sub' instruction must be either integer or floating point values. -This instruction can also take packed versions of the values. +This instruction can also take vector versions of the values. Both arguments must have identical types.
Semantics:
The value produced is the integer or floating point difference of the two operands.
Example:
-<result> = sub int 4, %var ; yields {int}:result = 4 - %var - <result> = sub int 0, %val ; yields {int}:result = -%var +<result> = sub i32 4, %var ; yields {i32}:result = 4 - %var + <result> = sub i32 0, %val ; yields {i32}:result = -%var@@ -1277,111 +1888,157 @@ operands.The two arguments to the 'mul' instruction must be either integer or floating point values. -This instruction can also take packed versions of the values. +This instruction can also take vector versions of the values. Both arguments must have identical types.
Semantics:
The value produced is the integer or floating point product of the two operands.
-There is no signed vs unsigned multiplication. The appropriate -action is taken based on the type of the operand.
+Because the operands are the same width, the result of an integer +multiplication is the same whether the operands should be deemed unsigned or +signed.
Example:
-<result> = mul int 4, %var ; yields {int}:result = 4 * %var +<result> = mul i32 4, %var ; yields {i32}:result = 4 * %var- +- +Syntax:
-<result> = div <ty> <var1>, <var2> ; yields {ty}:result +<result> = udiv <ty> <var1>, <var2> ; yields {ty}:resultOverview:
-The 'div' instruction returns the quotient of its two +
The 'udiv' instruction returns the quotient of its two operands.
Arguments:
-The two arguments to the 'div' instruction must be either integer or floating point -values. -This instruction can also take packed versions of the values. -Both arguments must have identical types.
+The two arguments to the 'udiv' instruction must be +integer values. Both arguments must have identical +types. This instruction can also take vector versions +of the values in which case the elements must be integers.
Semantics:
-The value produced is the integer or floating point quotient of the -two operands.
+The value produced is the unsigned integer quotient of the two operands. This +instruction always performs an unsigned division operation, regardless of +whether the arguments are unsigned or not.
Example:
-<result> = div int 4, %var ; yields {int}:result = 4 / %var +<result> = udiv i32 4, %var ; yields {i32}:result = 4 / %var- + +Syntax:
-<result> = rem <ty> <var1>, <var2> ; yields {ty}:result +<result> = sdiv <ty> <var1>, <var2> ; yields {ty}:resultOverview:
-The 'rem' instruction returns the remainder from the -division of its two operands.
+The 'sdiv' instruction returns the quotient of its two +operands.
Arguments:
-The two arguments to the 'rem' instruction must be either integer or floating point -values. -This instruction can also take packed versions of the values. -Both arguments must have identical types.
+The two arguments to the 'sdiv' instruction must be +integer values. Both arguments must have identical +types. This instruction can also take vector versions +of the values in which case the elements must be integers.
Semantics:
-This returns the remainder of a division (where the result -has the same sign as the divisor), not the modulus (where the -result has the same sign as the dividend) of a value. For more -information about the difference, see: The -Math Forum.
+The value produced is the signed integer quotient of the two operands. This +instruction always performs a signed division operation, regardless of whether +the arguments are signed or not.
Example:
-<result> = rem int 4, %var ; yields {int}:result = 4 % %var +<result> = sdiv i32 4, %var ; yields {i32}:result = 4 / %var++ + +Syntax:
+<result> = fdiv <ty> <var1>, <var2> ; yields {ty}:result ++Overview:
+The 'fdiv' instruction returns the quotient of its two +operands.
+Arguments:
+The two arguments to the 'div' instruction must be +floating point values. Both arguments must have +identical types. This instruction can also take vector +versions of the values in which case the elements must be floating point.
+Semantics:
+The value produced is the floating point quotient of the two operands.
+Example:
+<result> = fdiv float 4.0, %var ; yields {float}:result = 4.0 / %var ++++ +Syntax:
+<result> = urem <ty> <var1>, <var2> ; yields {ty}:result ++Overview:
+The 'urem' instruction returns the remainder from the +unsigned division of its two arguments.
+Arguments:
+The two arguments to the 'urem' instruction must be +integer values. Both arguments must have identical +types.
+Semantics:
+This instruction returns the unsigned integer remainder of a division. +This instruction always performs an unsigned division to get the remainder, +regardless of whether the arguments are unsigned or not.
+Example:
+<result> = urem i32 4, %var ; yields {i32}:result = 4 % %var ++ ++ + +Syntax:
-<result> = seteq <ty> <var1>, <var2> ; yields {bool}:result - <result> = setne <ty> <var1>, <var2> ; yields {bool}:result - <result> = setlt <ty> <var1>, <var2> ; yields {bool}:result - <result> = setgt <ty> <var1>, <var2> ; yields {bool}:result - <result> = setle <ty> <var1>, <var2> ; yields {bool}:result - <result> = setge <ty> <var1>, <var2> ; yields {bool}:result +<result> = srem <ty> <var1>, <var2> ; yields {ty}:resultOverview:
-The 'setcc' family of instructions returns a boolean -value based on a comparison of their two operands.
+The 'srem' instruction returns the remainder from the +signed division of its two operands.
Arguments:
-The two arguments to the 'setcc' instructions must -be of first class type (it is not possible -to compare 'label's, 'array's, 'structure' -or 'void' values, etc...). Both arguments must have identical +
The two arguments to the 'srem' instruction must be +integer values. Both arguments must have identical types.
Semantics:
-The 'seteq' instruction yields a true 'bool' -value if both operands are equal.
+
-The 'setne' instruction yields a true 'bool' -value if both operands are unequal.
-The 'setlt' instruction yields a true 'bool' -value if the first operand is less than the second operand.
-The 'setgt' instruction yields a true 'bool' -value if the first operand is greater than the second operand.
-The 'setle' instruction yields a true 'bool' -value if the first operand is less than or equal to the second operand.
-The 'setge' instruction yields a true 'bool' -value if the first operand is greater than or equal to the second -operand.This instruction returns the remainder of a division (where the result +has the same sign as the dividend, var1), not the modulo +operator (where the result has the same sign as the divisor, var2) of +a value. For more information about the difference, see The +Math Forum. For a table of how this is implemented in various languages, +please see +Wikipedia: modulo operation.
+Example:
+<result> = srem i32 4, %var ; yields {i32}:result = 4 % %var ++ +++ @@ -1393,6 +2050,89 @@ instructions. They require two operands, execute an operation on them, and produce a single value. The resulting value of the bitwise binary operators is always the same type as its first operand. + + + +Syntax:
+<result> = frem <ty> <var1>, <var2> ; yields {ty}:result ++Overview:
+The 'frem' instruction returns the remainder from the +division of its two operands.
+Arguments:
+The two arguments to the 'frem' instruction must be +floating point values. Both arguments must have +identical types.
+Semantics:
+This instruction returns the remainder of a division.
Example:
-<result> = seteq int 4, 5 ; yields {bool}:result = false - <result> = setne float 4, 5 ; yields {bool}:result = true - <result> = setlt uint 4, 5 ; yields {bool}:result = true - <result> = setgt sbyte 4, 5 ; yields {bool}:result = false - <result> = setle sbyte 4, 5 ; yields {bool}:result = true - <result> = setge sbyte 4, 5 ; yields {bool}:result = false +<result> = frem float 4.0, %var ; yields {float}:result = 4.0 % %var++ + +Syntax:
+<result> = shl <ty> <var1>, <var2> ; yields {ty}:result ++Overview:
+The 'shl' instruction returns the first operand shifted to +the left a specified number of bits.
+Arguments:
+Both arguments to the 'shl' instruction must be the same integer type.
+Semantics:
+The value produced is var1 * 2var2.
+Example:
+ <result> = shl i32 4, %var ; yields {i32}: 4 << %var + <result> = shl i32 4, 2 ; yields {i32}: 16 + <result> = shl i32 1, 10 ; yields {i32}: 1024 ++++ + + +Syntax:
+<result> = lshr <ty> <var1>, <var2> ; yields {ty}:result ++ +Overview:
+The 'lshr' instruction (logical shift right) returns the first +operand shifted to the right a specified number of bits.
+ +Arguments:
+Both arguments to the 'lshr' instruction must be the same +integer type.
+ +Semantics:
+This instruction always performs a logical shift right operation. The most +significant bits of the result will be filled with zero bits after the +shift.
+ +Example:
++ <result> = lshr i32 4, 1 ; yields {i32}:result = 2 + <result> = lshr i32 4, 2 ; yields {i32}:result = 1 + <result> = lshr i8 4, 3 ; yields {i8}:result = 0 + <result> = lshr i8 -2, 1 ; yields {i8}:result = 0x7FFFFFFF +++ ++ @@ -1405,7 +2145,7 @@ Instruction its two operands.Syntax:
+<result> = ashr <ty> <var1>, <var2> ; yields {ty}:result ++ +Overview:
+The 'ashr' instruction (arithmetic shift right) returns the first +operand shifted to the right a specified number of bits.
+ +Arguments:
+Both arguments to the 'ashr' instruction must be the same +integer type.
+ +Semantics:
+This instruction always performs an arithmetic shift right operation, +The most significant bits of the result will be filled with the sign bit +of var1.
+ +Example:
++ <result> = ashr i32 4, 1 ; yields {i32}:result = 2 + <result> = ashr i32 4, 2 ; yields {i32}:result = 1 + <result> = ashr i8 4, 3 ; yields {i8}:result = 0 + <result> = ashr i8 -2, 1 ; yields {i8}:result = -1 ++Arguments:
The two arguments to the 'and' instruction must be integral values. Both arguments must have + href="#t_integer">integer values. Both arguments must have identical types.
Semantics:
The truth table used for the 'and' instruction is:
@@ -1442,9 +2182,9 @@ identical types.Example:
-<result> = and int 4, %var ; yields {int}:result = 4 & %var - <result> = and int 15, 40 ; yields {int}:result = 8 - <result> = and int 4, 8 ; yields {int}:result = 0 +<result> = and i32 4, %var ; yields {i32}:result = 4 & %var + <result> = and i32 15, 40 ; yields {i32}:result = 8 + <result> = and i32 4, 8 ; yields {i32}:result = 0@@ -1458,7 +2198,7 @@ identical types. or of its two operands.Arguments:
The two arguments to the 'or' instruction must be integral values. Both arguments must have + href="#t_integer">integer values. Both arguments must have identical types.
Semantics:
The truth table used for the 'or' instruction is:
@@ -1495,9 +2235,9 @@ identical types.Example:
-<result> = or int 4, %var ; yields {int}:result = 4 | %var - <result> = or int 15, 40 ; yields {int}:result = 47 - <result> = or int 4, 8 ; yields {int}:result = 12 +<result> = or i32 4, %var ; yields {i32}:result = 4 | %var + <result> = or i32 15, 40 ; yields {i32}:result = 47 + <result> = or i32 4, 8 ; yields {i32}:result = 12@@ -1513,7 +2253,7 @@ or of its two operands. The xor is used to implement the "one's complement" operation, which is the "~" operator in C.Arguments:
The two arguments to the 'xor' instruction must be integral values. Both arguments must have + href="#t_integer">integer values. Both arguments must have identical types.
Semantics:
The truth table used for the 'xor' instruction is:
@@ -1551,153 +2291,326 @@ identical types.
Example:
-<result> = xor int 4, %var ; yields {int}:result = 4 ^ %var - <result> = xor int 15, 40 ; yields {int}:result = 39 - <result> = xor int 4, 8 ; yields {int}:result = 12 - <result> = xor int %V, -1 ; yields {int}:result = ~%V +<result> = xor i32 4, %var ; yields {i32}:result = 4 ^ %var + <result> = xor i32 15, 40 ; yields {i32}:result = 39 + <result> = xor i32 4, 8 ; yields {i32}:result = 12 + <result> = xor i32 %V, -1 ; yields {i32}:result = ~%V+ + + + ++ ++ - + +LLVM supports several instructions to represent vector operations in a +target-independent manner. This instructions cover the element-access and +vector-specific operations needed to process vectors effectively. While LLVM +does directly support these vector operations, many sophisticated algorithms +will want to use target-specific intrinsics to take full advantage of a specific +target.
+ +++ + - + + +Syntax:
-<result> = shl <ty> <var1>, ubyte <var2> ; yields {ty}:result + ++ <result> = extractelement <n x <ty>> <val>, i32 <idx> ; yields <ty>+Overview:
-The 'shl' instruction returns the first operand shifted to -the left a specified number of bits.
+ ++The 'extractelement' instruction extracts a single scalar +element from a vector at a specified index. +
+ +Arguments:
-The first argument to the 'shl' instruction must be an integer type. The second argument must be an 'ubyte' -type.
+ ++The first operand of an 'extractelement' instruction is a +value of vector type. The second operand is +an index indicating the position from which to extract the element. +The index may be a variable.
+Semantics:
-The value produced is var1 * 2var2.
+ ++The result is a scalar of the same type as the element type of +val. Its value is the value at position idx of +val. If idx exceeds the length of val, the +results are undefined. +
+Example:
-<result> = shl int 4, ubyte %var ; yields {int}:result = 4 << %var - <result> = shl int 4, ubyte 2 ; yields {int}:result = 16 - <result> = shl int 1, ubyte 10 ; yields {int}:result = 1024 + ++ %result = extractelement <4 x i32> %vec, i32 0 ; yields i32+ ++ + + +Syntax:
+ ++ <result> = insertelement <n x <ty>> <val>, <ty> <elt>, i32 <idx> ; yields <n x <ty>> ++ +Overview:
+ ++The 'insertelement' instruction inserts a scalar +element into a vector at a specified index. +
+ + +Arguments:
+ ++The first operand of an 'insertelement' instruction is a +value of vector type. The second operand is a +scalar value whose type must equal the element type of the first +operand. The third operand is an index indicating the position at +which to insert the value. The index may be a variable.
+ +Semantics:
+ ++The result is a vector of the same type as val. Its +element values are those of val except at position +idx, where it gets the value elt. If idx +exceeds the length of val, the results are undefined. +
+ +Example:
+ ++ %result = insertelement <4 x i32> %vec, i32 1, i32 0 ; yields <4 x i32> ++++ + - + +Syntax:
-<result> = shr <ty> <var1>, ubyte <var2> ; yields {ty}:result + ++ <result> = shufflevector <n x <ty>> <v1>, <n x <ty>> <v2>, <n x i32> <mask> ; yields <n x <ty>>+Overview:
-The 'shr' instruction returns the first operand shifted to -the right a specified number of bits.
+ ++The 'shufflevector' instruction constructs a permutation of elements +from two input vectors, returning a vector of the same type. +
+Arguments:
-The first argument to the 'shr' instruction must be an integer type. The second argument must be an 'ubyte' -type.
+ ++The first two operands of a 'shufflevector' instruction are vectors +with types that match each other and types that match the result of the +instruction. The third argument is a shuffle mask, which has the same number +of elements as the other vector type, but whose element type is always 'i32'. +
+ ++The shuffle mask operand is required to be a constant vector with either +constant integer or undef values. +
+Semantics:
-If the first argument is a signed type, the -most significant bit is duplicated in the newly free'd bit positions. -If the first argument is unsigned, zero bits shall fill the empty -positions.
+ ++The elements of the two input vectors are numbered from left to right across +both of the vectors. The shuffle mask operand specifies, for each element of +the result vector, which element of the two input registers the result element +gets. The element selector may be undef (meaning "don't care") and the second +operand may be undef if performing a shuffle from only one vector. +
+Example:
-<result> = shr int 4, ubyte %var ; yields {int}:result = 4 >> %var - <result> = shr uint 4, ubyte 1 ; yields {uint}:result = 2 - <result> = shr int 4, ubyte 2 ; yields {int}:result = 1 - <result> = shr sbyte 4, ubyte 3 ; yields {sbyte}:result = 0 - <result> = shr sbyte -2, ubyte 1 ; yields {sbyte}:result = -1 + ++ %result = shufflevector <4 x i32> %v1, <4 x i32> %v2, + <4 x i32> <i32 0, i32 4, i32 1, i32 5> ; yields <4 x i32> + %result = shufflevector <4 x i32> %v1, <4 x i32> undef, + <4 x i32> <i32 0, i32 1, i32 2, i32 3> ; yields <4 x i32> - Identity shuffle.++ - + +A key design point of an SSA-based representation is how it represents memory. In LLVM, no memory locations are in SSA form, which makes things very simple. This section describes how to read, write, allocate, and free memory in LLVM.
+++ - + +Syntax:
-<result> = malloc <type>, uint <NumElements> ; yields {type*}:result - <result> = malloc <type> ; yields {type*}:result + ++ <result> = malloc <type>[, i32 <NumElements>][, align <alignment>] ; yields {type*}:result+Overview:
+The 'malloc' instruction allocates memory from the system heap and returns a pointer to it.
+Arguments:
-The 'malloc' instruction allocates sizeof(<type>)*NumElements + +
The 'malloc' instruction allocates +sizeof(<type>)*NumElements bytes of memory from the operating system and returns a pointer of the -appropriate type to the program. The second form of the instruction is -a shorter version of the first instruction that defaults to allocating -one element.
+appropriate type to the program. If "NumElements" is specified, it is the +number of elements allocated. If an alignment is specified, the value result +of the allocation is guaranteed to be aligned to at least that boundary. If +not specified, or if zero, the target can choose to align the allocation on any +convenient boundary. +'type' must be a sized type.
+Semantics:
+Memory is allocated using the system "malloc" function, and a pointer is returned.
+Example:
-%array = malloc [4 x ubyte ] ; yields {[%4 x ubyte]*}:array - %size = add uint 2, 2 ; yields {uint}:size = uint 4 - %array1 = malloc ubyte, uint 4 ; yields {ubyte*}:array1 - %array2 = malloc [12 x ubyte], uint %size ; yields {[12 x ubyte]*}:array2 ++ %array = malloc [4 x i8 ] ; yields {[%4 x i8]*}:array + + %size = add i32 2, 2 ; yields {i32}:size = i32 4 + %array1 = malloc i8, i32 4 ; yields {i8*}:array1 + %array2 = malloc [12 x i8], i32 %size ; yields {[12 x i8]*}:array2 + %array3 = malloc i32, i32 4, align 1024 ; yields {i32*}:array3 + %array4 = malloc i32, align 1024 ; yields {i32*}:array4++ - + +Syntax:
-free <type> <value> ; yields {void} + ++ free <type> <value> ; yields {void}+Overview:
+The 'free' instruction returns memory back to the unused -memory heap, to be reallocated in the future.
-+memory heap to be reallocated in the future. +
Arguments:
+'value' shall be a pointer value that points to a value that was allocated with the 'malloc' instruction.
+Semantics:
+Access to the memory pointed to by the pointer is no longer defined after this instruction executes.
+Example:
-%array = malloc [4 x ubyte] ; yields {[4 x ubyte]*}:array - free [4 x ubyte]* %array + ++ %array = malloc [4 x i8] ; yields {[4 x i8]*}:array + free [4 x i8]* %array++ @@ -1708,24 +2621,25 @@ InstructionSyntax:
-<result> = alloca <type>, uint <NumElements> ; yields {type*}:result - <result> = alloca <type> ; yields {type*}:result + ++ <result> = alloca <type>[, i32 <NumElements>][, align <alignment>] ; yields {type*}:result+Overview:
+The 'alloca' instruction allocates memory on the current stack frame of the procedure that is live until the current function returns to its caller.
+Arguments:
+The 'alloca' instruction allocates sizeof(<type>)*NumElements bytes of memory on the runtime stack, returning a pointer of the -appropriate type to the program. The second form of the instruction is -a shorter version of the first that defaults to allocating one element.
+appropriate type to the program. If "NumElements" is specified, it is the +number of elements allocated. If an alignment is specified, the value result +of the allocation is guaranteed to be aligned to at least that boundary. If +not specified, or if zero, the target can choose to align the allocation on any +convenient boundary. +'type' may be any sized type.
+Semantics:
-Memory is allocated, a pointer is returned. 'alloca'd + +
Memory is allocated; a pointer is returned. 'alloca'd memory is automatically released when the function returns. The 'alloca' instruction is commonly used to represent automatic variables that must have an address available. When the function returns (either with the ret or invoke + href="#i_ret">ret or unwind instructions), the memory is reclaimed.
+Example:
-%ptr = alloca int ; yields {int*}:ptr - %ptr = alloca int, uint 4 ; yields {int*}:ptr + ++ %ptr = alloca i32 ; yields {i32*}:ptr + %ptr = alloca i32, i32 4 ; yields {i32*}:ptr + %ptr = alloca i32, i32 4, align 1024 ; yields {i32*}:ptr + %ptr = alloca i32, align 1024 ; yields {i32*}:ptrThe 'load' instruction is used to read from memory.
Arguments:
The argument to the 'load' instruction specifies the memory -address to load from. The pointer must point to a first class type. If the load is -marked as volatile then the optimizer is not allowed to modify +marked as volatile, then the optimizer is not allowed to modify the number or order of execution of this load with other volatile load and store instructions.
Semantics:
The location of memory pointed to is loaded.
Examples:
-%ptr = alloca int ; yields {int*}:ptr ++ +%ptr = alloca i32 ; yields {i32*}:ptr store int 3, int* %ptr ; yields {void} - %val = load int* %ptr ; yields {int}:val = int 3 + href="#i_store">store i32 3, i32* %ptr ; yields {void} + %val = load i32* %ptr ; yields {i32}:val = i32 3+Syntax:
store <ty> <value>, <ty>* <pointer> ; yields {void} volatile store <ty> <value>, <ty>* <pointer> ; yields {void} @@ -1734,9 +2648,9 @@ InstructionThe 'store' instruction is used to write to memory.
Arguments:
There are two arguments to the 'store' instruction: a value -to store and an address to store it into. The type of the '<pointer>' +to store and an address in which to store it. The type of the '<pointer>' operand must be a pointer to the type of the '<value>' -operand. If the store is marked as volatile then the +operand. If the store is marked as volatile, then the optimizer is not allowed to modify the number or order of execution of this store with other volatile load and store instructions.
@@ -1744,11 +2658,13 @@ this store with other volatile load and The contents of memory are updated to contain '<value>' at the location specified by the '<pointer>' operand.Example:
-%ptr = alloca int ; yields {int*}:ptr +i32 3, i32* %ptr ; yields {void} + %val = load i32* %ptr ; yields {i32}:val = i32 3%ptr = alloca i32 ; yields {i32*}:ptr store int 3, int* %ptr ; yields {void} - %val = load int* %ptr ; yields {int}:val = int 3 + href="#i_store">store'getelementptr' Instruction @@ -1768,13 +2684,14 @@ subelement of an aggregate data structure.+ - +Arguments:
-This instruction takes a list of integer constants that indicate what +
This instruction takes a list of integer operands that indicate what elements of the aggregate object to index to. The actual types of the arguments provided depend on the type of the first pointer argument. The 'getelementptr' instruction is used to index down through the type -levels of a structure. When indexing into a structure, only uint -integer constants are allowed. When indexing into an array or pointer -int and long indexes are allowed of any sign.
+levels of a structure or to a specific index in an array. When indexing into a +structure, only i32 integer constants are allowed. When indexing +into an array or pointer, only integers of 32 or 64 bits are allowed, and will +be sign extended to 64-bit values.For example, let's consider a C code fragment and how it gets compiled to LLVM:
@@ -1782,16 +2699,16 @@ compiled to LLVM:struct RT { char A; - int B[10][20]; + i32 B[10][20]; char C; }; struct ST { - int X; + i32 X; double Y; struct RT Z; }; - int *foo(struct ST *s) { + define i32 *foo(struct ST *s) { return &s[1].Z.B[5][13]; }@@ -1799,152 +2716,199 @@ compiled to LLVM:The LLVM code generated by the GCC frontend is:
- %RT = type { sbyte, [10 x [20 x int]], sbyte } - %ST = type { int, double, %RT } + %RT = type { i8 , [10 x [20 x i32]], i8 } + %ST = type { i32, double, %RT } implementation - int* %foo(%ST* %s) { + define i32* %foo(%ST* %s) { entry: - %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13 - ret int* %reg + %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13 + ret i32* %reg }Semantics:
The index types specified for the 'getelementptr' instruction depend -on the pointer type that is being index into. Pointer -and array types require uint, int, -ulong, or long values, and structure -types require uint constants.
+on the pointer type that is being indexed into. Pointer +and array types can use a 32-bit or 64-bit +integer type but the value will always be sign extended +to 64-bits. Structure types, require i32 +constants.In the example above, the first index is indexing into the '%ST*' -type, which is a pointer, yielding a '%ST' = '{ int, double, %RT +type, which is a pointer, yielding a '%ST' = '{ i32, double, %RT }' type, a structure. The second index indexes into the third element of -the structure, yielding a '%RT' = '{ sbyte, [10 x [20 x int]], -sbyte }' type, another structure. The third index indexes into the second -element of the structure, yielding a '[10 x [20 x int]]' type, an +the structure, yielding a '%RT' = '{ i8 , [10 x [20 x i32]], +i8 }' type, another structure. The third index indexes into the second +element of the structure, yielding a '[10 x [20 x i32]]' type, an array. The two dimensions of the array are subscripted into, yielding an -'int' type. The 'getelementptr' instruction return a pointer -to this element, thus computing a value of 'int*' type.
+'i32' type. The 'getelementptr' instruction returns a pointer +to this element, thus computing a value of 'i32*' type.Note that it is perfectly legal to index partially through a structure, returning a pointer to an inner element. Because of this, the LLVM code for the given testcase is equivalent to:
- int* "foo"(%ST* %s) { - %t1 = getelementptr %ST* %s, int 1 ; yields %ST*:%t1 - %t2 = getelementptr %ST* %t1, int 0, uint 2 ; yields %RT*:%t2 - %t3 = getelementptr %RT* %t2, int 0, uint 1 ; yields [10 x [20 x int]]*:%t3 - %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 ; yields [20 x int]*:%t4 - %t5 = getelementptr [20 x int]* %t4, int 0, int 13 ; yields int*:%t5 - ret int* %t5 + define i32* %foo(%ST* %s) { + %t1 = getelementptr %ST* %s, i32 1 ; yields %ST*:%t1 + %t2 = getelementptr %ST* %t1, i32 0, i32 2 ; yields %RT*:%t2 + %t3 = getelementptr %RT* %t2, i32 0, i32 1 ; yields [10 x [20 x i32]]*:%t3 + %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 ; yields [20 x i32]*:%t4 + %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 ; yields i32*:%t5 + ret i32* %t5 }+ +Note that it is undefined to access an array out of bounds: array and +pointer indexes must always be within the defined bounds of the array type. +The one exception for this rules is zero length arrays. These arrays are +defined to be accessible as variable length arrays, which requires access +beyond the zero'th element.
+ +The getelementptr instruction is often confusing. For some more insight +into how it works, see the getelementptr +FAQ.
+Example:
+- ; yields [12 x ubyte]*:aptr - %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1 + ; yields [12 x i8]*:aptr + %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1--+ - +The instructions in this category are the "miscellaneous" -instructions, which defy better classification.
+The instructions in this category are the conversion instructions (casting) +which all take a single operand and a type. They perform various bit conversions +on the operand.
+-Syntax:
-<result> = phi <ty> [ <val0>, <label0>], ...++ <result> = trunc <ty> <value> to <ty2> ; yields ty2 ++Overview:
-The 'phi' instruction is used to implement the φ node in -the SSA graph representing the function.
++The 'trunc' instruction truncates its operand to the type ty2. +
+Arguments:
-The type of the incoming values are specified with the first type -field. After this, the 'phi' instruction takes a list of pairs -as arguments, with one pair for each predecessor basic block of the -current block. Only values of first class -type may be used as the value arguments to the PHI node. Only labels -may be used as the label arguments.
-There must be no non-phi instructions between the start of a basic -block and the PHI instructions: i.e. PHI instructions must be first in -a basic block.
++The 'trunc' instruction takes a value to trunc, which must +be an integer type, and a type that specifies the size +and type of the result, which must be an integer +type. The bit size of value must be larger than the bit size of +ty2. Equal sized types are not allowed.
+Semantics:
-At runtime, the 'phi' instruction logically takes on the -value specified by the parameter, depending on which basic block we -came from in the last terminator instruction.
++The 'trunc' instruction truncates the high order bits in value +and converts the remaining bits to ty2. Since the source size must be +larger than the destination size, trunc cannot be a no-op cast. +It will always truncate bits.
+Example:
-Loop: ; Infinite loop that counts from 0 on up...+
%indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
%nextindvar = add uint %indvar, 1
br label %Loop+ %X = trunc i32 257 to i8 ; yields i8:1 + %Y = trunc i32 123 to i1 ; yields i1:true + %Y = trunc i32 122 to i1 ; yields i1:false ++ + + +Syntax:
-- <result> = cast <ty> <value> to <ty2> ; yields ty2 + <result> = zext <ty> <value> to <ty2> ; yields ty2Overview:
- --The 'cast' instruction is used as the primitive means to convert -integers to floating point, change data type sizes, and break type safety (by -casting pointers). -
+The 'zext' instruction zero extends its operand to type +ty2.
Arguments:
- --The 'cast' instruction takes a value to cast, which must be a first -class value, and a type to cast it to, which must also be a first class type. -
+The 'zext' instruction takes a value to cast, which must be of +integer type, and a type to cast it to, which must +also be of integer type. The bit size of the +value must be smaller than the bit size of the destination type, +ty2.
Semantics:
+The zext fills the high order bits of the value with zero +bits until it reaches the size of the destination type, ty2. When the +the operand and the type are the same size, no bit filling is done and the +cast is considered a no-op cast because no bits change (only the type +changes).
--This instruction follows the C rules for explicit casts when determining how the -data being cast must change to fit in its new container. -
+When zero extending from i1, the result will always be either 0 or 1.
+ +Example:
++ %X = zext i32 257 to i64 ; yields i64:257 + %Y = zext i1 true to i32 ; yields i32:1 +++ +Syntax:
++ <result> = sext <ty> <value> to <ty2> ; yields ty2 ++ +Overview:
+The 'sext' sign extends value to the type ty2.
+Arguments:
-When casting to bool, any value that would be considered true in the context of -a C 'if' condition is converted to the boolean 'true' values, -all else are 'false'. -
+The 'sext' instruction takes a value to cast, which must be of +integer type, and a type to cast it to, which must +also be of integer type. The bit size of the +value must be smaller than the bit size of the destination type, +ty2. +Semantics:
-When extending an integral value from a type of one signness to another (for -example 'sbyte' to 'ulong'), the value is sign-extended if the -source value is signed, and zero-extended if the source value is -unsigned. bool values are always zero extended into either zero or -one. -
+The 'sext' instruction performs a sign extension by copying the sign +bit (highest order bit) of the value until it reaches the bit size of +the type ty2. When the the operand and the type are the same size, +no bit filling is done and the cast is considered a no-op cast because +no bits change (only the type changes). -Example:
+When sign extending from i1, the extension always results in -1 or 0.
+Example:
- %X = cast int 257 to ubyte ; yields ubyte:1 - %Y = cast int 123 to bool ; yields bool:true + %X = sext i8 -1 to i16 ; yields i16 :65535 + %Y = sext i1 true to i32 ; yields i32:-1@@ -1952,137 +2916,630 @@ one.+ + + +Syntax:
- <result> = select bool <cond>, <ty> <val1>, <ty> <val2> ; yields ty + <result> = fptrunc <ty> <value> to <ty2> ; yields ty2Overview:
+The 'fptrunc' instruction truncates value to type +ty2.
--The 'select' instruction is used to choose one value based on a -condition, without branching. -
+Arguments:
+The 'fptrunc' instruction takes a floating + point value to cast and a floating point type to +cast it to. The size of value must be larger than the size of +ty2. This implies that fptrunc cannot be used to make a +no-op cast.
+ +Semantics:
+The 'fptrunc' instruction truncates a value from a larger +floating point type to a smaller +floating point type. If the value cannot fit within +the destination type, ty2, then the results are undefined.
+ +Example:
++ %X = fptrunc double 123.0 to float ; yields float:123.0 + %Y = fptrunc double 1.0E+300 to float ; yields undefined +++ ++ + + +Syntax:
++ <result> = fpext <ty> <value> to <ty2> ; yields ty2 ++ +Overview:
+The 'fpext' extends a floating point value to a larger +floating point value.
Arguments:
+The 'fpext' instruction takes a +floating point value to cast, +and a floating point type to cast it to. The source +type must be smaller than the destination type.
--The 'select' instruction requires a boolean value indicating the condition, and two values of the same first class type. +
Semantics:
+The 'fpext' instruction extends the value from a smaller +floating point type to a larger +floating point type. The fpext cannot be +used to make a no-op cast because it always changes bits. Use +bitcast to make a no-op cast for a floating point cast.
+ +Example:
++ %X = fpext float 3.1415 to double ; yields double:3.1415 + %Y = fpext float 1.0 to float ; yields float:1.0 (no-op) +++ ++ + + +Syntax:
++ <result> = fp2uint <ty> <value> to <ty2> ; yields ty2 ++ +Overview:
+The 'fp2uint' converts a floating point value to its +unsigned integer equivalent of type ty2.
+Arguments:
+The 'fp2uint' instruction takes a value to cast, which must be a +floating point value, and a type to cast it to, which +must be an integer type.
+Semantics:
+The 'fp2uint' instruction converts its +floating point operand into the nearest (rounding +towards zero) unsigned integer value. If the value cannot fit in ty2, +the results are undefined.
--If the boolean condition evaluates to true, the instruction returns the first -value argument, otherwise it returns the second value argument. +
When converting to i1, the conversion is done as a comparison against +zero. If the value was zero, the i1 result will be false. +If the value was non-zero, the i1 result will be true.
+ +Example:
++ %X = fp2uint double 123.0 to i32 ; yields i32:123 + %Y = fp2uint float 1.0E+300 to i1 ; yields i1:true + %X = fp2uint float 1.04E+17 to i8 ; yields undefined:1 +++ ++ + + +Syntax:
++ <result> = fptosi <ty> <value> to <ty2> ; yields ty2 ++ +Overview:
+The 'fptosi' instruction converts +floating point value to type ty2.
+ +Arguments:
+The 'fptosi' instruction takes a value to cast, which must be a +floating point value, and a type to cast it to, which +must also be an integer type.
+ +Semantics:
+The 'fptosi' instruction converts its +floating point operand into the nearest (rounding +towards zero) signed integer value. If the value cannot fit in ty2, +the results are undefined.
+ +When converting to i1, the conversion is done as a comparison against +zero. If the value was zero, the i1 result will be false. +If the value was non-zero, the i1 result will be true.
+Example:
++ %X = fptosi double -123.0 to i32 ; yields i32:-123 + %Y = fptosi float 1.0E-247 to i1 ; yields i1:true + %X = fptosi float 1.04E+17 to i8 ; yields undefined:1 +++ ++ + +Syntax:
++ <result> = uitofp <ty> <value> to <ty2> ; yields ty2 ++ +Overview:
+The 'uitofp' instruction regards value as an unsigned +integer and converts that value to the ty2 type.
+ +Arguments:
+The 'uitofp' instruction takes a value to cast, which must be an +integer value, and a type to cast it to, which must +be a floating point type.
+ +Semantics:
+The 'uitofp' instruction interprets its operand as an unsigned +integer quantity and converts it to the corresponding floating point value. If +the value cannot fit in the floating point value, the results are undefined.
+ + +Example:
- %X = select bool true, ubyte 17, ubyte 42 ; yields ubyte:17 + %X = uitofp i32 257 to float ; yields float:257.0 + %Y = uitofp i8 -1 to double ; yields double:255.0+- +Syntax:
++ <result> = sitofp <ty> <value> to <ty2> ; yields ty2 ++Overview:
+The 'sitofp' instruction regards value as a signed +integer and converts that value to the ty2 type.
+Arguments:
+The 'sitofp' instruction takes a value to cast, which must be an +integer value, and a type to cast it to, which must be +a floating point type.
+ +Semantics:
+The 'sitofp' instruction interprets its operand as a signed +integer quantity and converts it to the corresponding floating point value. If +the value cannot fit in the floating point value, the results are undefined.
+ +Example:
++ %X = sitofp i32 257 to float ; yields float:257.0 + %Y = sitofp i8 -1 to double ; yields double:-1.0 ++++ + + +Syntax:
-<result> = call <ty>* <fnptrval>(<param list>)++ <result> = ptrtoint <ty> <value> to <ty2> ; yields ty2 ++Overview:
-The 'call' instruction represents a simple function call.
+The 'ptrtoint' instruction converts the pointer value to +the integer type ty2.
+Arguments:
-This instruction requires several arguments:
+The 'ptrtoint' instruction takes a value to cast, which +must be a pointer value, and a type to cast it to +ty2, which must be an integer type. + +
Semantics:
+The 'ptrtoint' instruction converts value to integer type +ty2 by interpreting the pointer value as an integer and either +truncating or zero extending that value to the size of the integer type. If +value is smaller than ty2 then a zero extension is done. If +value is larger than ty2 then a truncation is done. If they +are the same size, then nothing is done (no-op cast).
+ +Example:
++ %X = ptrtoint i32* %X to i8 ; yields truncation on 32-bit + %Y = ptrtoint i32* %x to i64 ; yields zero extend on 32-bit +++ ++ + + +Syntax:
++ <result> = inttoptr <ty> <value> to <ty2> ; yields ty2 ++ +Overview:
+The 'inttoptr' instruction converts an integer value to +a pointer type, ty2.
+ +Arguments:
+The 'inttoptr' instruction takes an integer +value to cast, and a type to cast it to, which must be a +pointer type. + +
Semantics:
+The 'inttoptr' instruction converts value to type +ty2 by applying either a zero extension or a truncation depending on +the size of the integer value. If value is larger than the +size of a pointer then a truncation is done. If value is smaller than +the size of a pointer then a zero extension is done. If they are the same size, +nothing is done (no-op cast).
+ +Example:
++ %X = inttoptr i32 255 to i32* ; yields zero extend on 64-bit + %X = inttoptr i32 255 to i32* ; yields no-op on 32-bit + %Y = inttoptr i16 0 to i32* ; yields zero extend on 32-bit +++ ++ + + +Syntax:
++ <result> = bitcast <ty> <value> to <ty2> ; yields ty2 ++ +Overview:
+The 'bitcast' instruction converts value to type +ty2 without changing any bits.
+ +Arguments:
+The 'bitcast' instruction takes a value to cast, which must be +a first class value, and a type to cast it to, which must also be a first class type. The bit sizes of value +and the destination type, ty2, must be identical. If the source +type is a pointer, the destination type must also be a pointer.
+ +Semantics:
+The 'bitcast' instruction converts value to type +ty2. It is always a no-op cast because no bits change with +this conversion. The conversion is done as if the value had been +stored to memory and read back as type ty2. Pointer types may only be +converted to other pointer types with this instruction. To convert pointers to +other types, use the inttoptr or +ptrtoint instructions first.
+ +Example:
++ %X = bitcast i8 255 to i8 ; yields i8 :-1 + %Y = bitcast i32* %x to sint* ; yields sint*:%x + %Z = bitcast <2xint> %V to i64; ; yields i64: %V ++++ + + +The instructions in this category are the "miscellaneous" +instructions, which defy better classification.
+++ + + +Syntax:
+<result> = icmp <cond> <ty> <var1>, <var2> +; yields {i1}:result ++Overview:
+The 'icmp' instruction returns a boolean value based on comparison +of its two integer operands.
+Arguments:
+The 'icmp' instruction takes three operands. The first operand is +the condition code which indicates the kind of comparison to perform. It is not +a value, just a keyword. The possibilities for the condition code are:
-
+- -
-'ty': shall be the signature of the pointer to function -value being invoked. The argument types must match the types implied -by this signature.
-- -
-'fnptrval': An LLVM value containing a pointer to a -function to be invoked. In most cases, this is a direct function -invocation, but indirect calls are just as possible, -calling an arbitrary pointer to function values.
-- -
'function args': argument list whose types match the -function signature argument types. If the function signature -indicates the function accepts a variable number of arguments, the -extra arguments can be specified.
+- eq: equal
+- ne: not equal
+- ugt: unsigned greater than
+- uge: unsigned greater or equal
+- ult: unsigned less than
+- ule: unsigned less or equal
+- sgt: signed greater than
+- sge: signed greater or equal
+- slt: signed less than
+- sle: signed less or equal
+The remaining two arguments must be integer or +pointer typed. They must also be identical types.
+Semantics:
+The 'icmp' compares var1 and var2 according to +the condition code given as cond. The comparison performed always +yields a i1 result, as follows: +
+
+- eq: yields true if the operands are equal, + false otherwise. No sign interpretation is necessary or performed.
+- ne: yields true if the operands are unequal, + false otherwise. No sign interpretation is necessary or performed. +
- ugt: interprets the operands as unsigned values and yields + true if var1 is greater than var2.
+- uge: interprets the operands as unsigned values and yields + true if var1 is greater than or equal to var2.
+- ult: interprets the operands as unsigned values and yields + true if var1 is less than var2.
+- ule: interprets the operands as unsigned values and yields + true if var1 is less than or equal to var2.
+- sgt: interprets the operands as signed values and yields + true if var1 is greater than var2.
+- sge: interprets the operands as signed values and yields + true if var1 is greater than or equal to var2.
+- slt: interprets the operands as signed values and yields + true if var1 is less than var2.
+- sle: interprets the operands as signed values and yields + true if var1 is less than or equal to var2.
If the operands are pointer typed, the pointer +values are treated as integers and then compared.
+ +Example:
+<result> = icmp eq i32 4, 5 ; yields: result=false + <result> = icmp ne float* %X, %X ; yields: result=false + <result> = icmp ult i16 4, 5 ; yields: result=true + <result> = icmp sgt i16 4, 5 ; yields: result=false + <result> = icmp ule i16 -4, 5 ; yields: result=false + <result> = icmp sge i16 4, 5 ; yields: result=false ++++ + + +Syntax:
+<result> = fcmp <cond> <ty> <var1>, <var2> +; yields {i1}:result ++Overview:
+The 'fcmp' instruction returns a boolean value based on comparison +of its floating point operands.
+Arguments:
+The 'fcmp' instruction takes three operands. The first operand is +the condition code which indicates the kind of comparison to perform. It is not +a value, just a keyword. The possibilities for the condition code are: +
+
+- false: no comparison, always returns false
+- oeq: ordered and equal
+- ogt: ordered and greater than
+- oge: ordered and greater than or equal
+- olt: ordered and less than
+- ole: ordered and less than or equal
+- one: ordered and not equal
+- ord: ordered (no nans)
+- ueq: unordered or equal
+- ugt: unordered or greater than
+- uge: unordered or greater than or equal
+- ult: unordered or less than
+- ule: unordered or less than or equal
+- une: unordered or not equal
+- uno: unordered (either nans)
+- true: no comparison, always returns true
+In the preceding, ordered means that neither operand is a QNAN while +unordered means that either operand may be a QNAN.
+The val1 and val2 arguments must be +floating point typed. They must have identical +types.
+In the foregoing, ordered means that neither operand is a QNAN and +unordered means that either operand is a QNAN.
Semantics:
-The 'call' instruction is used to cause control flow to -transfer to a specified function, with its incoming arguments bound to -the specified values. Upon a 'ret' -instruction in the called function, control flow continues with the -instruction after the function call, and the return value of the -function is bound to the result argument. This is a simpler case of -the invoke instruction.
+The 'fcmp' compares var1 and var2 according to +the condition code given as cond. The comparison performed always +yields a i1 result, as follows: +
+
+- false: always yields false, regardless of operands.
+- oeq: yields true if both operands are not a QNAN and + var1 is equal to var2.
+- ogt: yields true if both operands are not a QNAN and + var1 is greather than var2.
+- oge: yields true if both operands are not a QNAN and + var1 is greater than or equal to var2.
+- olt: yields true if both operands are not a QNAN and + var1 is less than var2.
+- ole: yields true if both operands are not a QNAN and + var1 is less than or equal to var2.
+- one: yields true if both operands are not a QNAN and + var1 is not equal to var2.
+- ord: yields true if both operands are not a QNAN.
+- ueq: yields true if either operand is a QNAN or + var1 is equal to var2.
+- ugt: yields true if either operand is a QNAN or + var1 is greater than var2.
+- uge: yields true if either operand is a QNAN or + var1 is greater than or equal to var2.
+- ult: yields true if either operand is a QNAN or + var1 is less than var2.
+- ule: yields true if either operand is a QNAN or + var1 is less than or equal to var2.
+- une: yields true if either operand is a QNAN or + var1 is not equal to var2.
+- uno: yields true if either operand is a QNAN.
+- true: always yields true, regardless of operands.
+Example:
-%retval = call int %test(int %argc)+
call int(sbyte*, ...) *%printf(sbyte* %msg, int 12, sbyte 42);<result> = fcmp oeq float 4.0, 5.0 ; yields: result=false + <result> = icmp one float 4.0, 5.0 ; yields: result=true + <result> = icmp olt float 4.0, 5.0 ; yields: result=true + <result> = icmp ueq double 1.0, 2.0 ; yields: result=false ++++ + + + +Syntax:
+<result> = phi <ty> [ <val0>, <label0>], ...+Overview:
+The 'phi' instruction is used to implement the φ node in +the SSA graph representing the function.
+Arguments:
+The type of the incoming values are specified with the first type +field. After this, the 'phi' instruction takes a list of pairs +as arguments, with one pair for each predecessor basic block of the +current block. Only values of first class +type may be used as the value arguments to the PHI node. Only labels +may be used as the label arguments.
+There must be no non-phi instructions between the start of a basic +block and the PHI instructions: i.e. PHI instructions must be first in +a basic block.
+Semantics:
+At runtime, the 'phi' instruction logically takes on the +value specified by the parameter, depending on which basic block we +came from in the last terminator instruction.
+Example:
+Loop: ; Infinite loop that counts from 0 on up...+
%indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
%nextindvar = add i32 %indvar, 1
br label %Loop+ ++Syntax:
+ ++ <result> = select i1 <cond>, <ty> <val1>, <ty> <val2> ; yields ty ++ +Overview:
+ ++The 'select' instruction is used to choose one value based on a +condition, without branching. +
+ + +Arguments:
+ ++The 'select' instruction requires a boolean value indicating the condition, and two values of the same first class type. +
+ +Semantics:
+ ++If the boolean condition evaluates to true, the instruction returns the first +value argument; otherwise, it returns the second value argument. +
+ +Example:
+ ++ %X = select i1 true, i8 17, i8 42 ; yields i8:17 +Syntax:
-- <resultarglist> = vanext <va_list> <arglist>, <argty> + <result> = [tail] call [cconv] <ty>* <fnptrval>(<param list>)Overview:
-The 'vanext' instruction is used to access arguments passed -through the "variable argument" area of a function call. It is used to -implement the va_arg macro in C.
+The 'call' instruction represents a simple function call.
Arguments:
-This instruction takes a va_list value and the type of the -argument. It returns another va_list. The actual type of -va_list may be defined differently for different targets. Most targets -use a va_list type of sbyte* or some other pointer type.
- -Semantics:
+This instruction requires several arguments:
-The 'vanext' instruction advances the specified va_list -past an argument of the specified type. In conjunction with the vaarg instruction, it is used to implement -the va_arg macro available in C. For more information, see -the variable argument handling Intrinsic -Functions.
++
-- +
+The optional "tail" marker indicates whether the callee function accesses + any allocas or varargs in the caller. If the "tail" marker is present, the + function call is eligible for tail call optimization. Note that calls may + be marked "tail" even if they do not occur before a ret instruction. +
- +
+The optional "cconv" marker indicates which calling + convention the call should use. If none is specified, the call defaults + to using C calling conventions. +
- +
+'ty': shall be the signature of the pointer to function value + being invoked. The argument types must match the types implied by this + signature. This type can be omitted if the function is not varargs and + if the function type does not return a pointer to a function.
+- +
+'fnptrval': An LLVM value containing a pointer to a function to + be invoked. In most cases, this is a direct function invocation, but + indirect calls are just as possible, calling an arbitrary pointer + to function value.
+- +
+'function args': argument list whose types match the + function signature argument types. All arguments must be of + first class type. If the function signature + indicates the function accepts a variable number of arguments, the extra + arguments can be specified.
+It is legal for this instruction to be called in a function which -does not take a variable number of arguments, for example, the vfprintf -function.
+Semantics:
-vanext is an LLVM instruction instead of an intrinsic function because it takes a type as an -argument. The type refers to the current argument in the va_list, it -tells the compiler how far on the stack it needs to advance to find the next -argument
+The 'call' instruction is used to cause control flow to +transfer to a specified function, with its incoming arguments bound to +the specified values. Upon a 'ret' +instruction in the called function, control flow continues with the +instruction after the function call, and the return value of the +function is bound to the result argument. This is a simpler case of +the invoke instruction.
Example:
-See the variable argument processing -section.
++ %retval = call i32 %test(i32 %argc) + call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42); + %X = tail call i32 %foo() + %Y = tail call fastcc i32 %foo() +@@ -2090,35 +3547,36 @@ section.@@ -2309,7 +3782,7 @@ href="GarbageCollection.html">Accurate Garbage Collection with LLVM.Syntax:
- <resultval> = vaarg <va_list> <arglist>, <argty> + <resultval> = va_arg <va_list*> <arglist>, <argty>Overview:
-The 'vaarg' instruction is used to access arguments passed through +
The 'va_arg' instruction is used to access arguments passed through the "variable argument" area of a function call. It is used to implement the va_arg macro in C.
Arguments:
-This instruction takes a va_list value and the type of the -argument. It returns a value of the specified argument type. Again, the actual -type of va_list is target specific.
+This instruction takes a va_list* value and the type of +the argument. It returns a value of the specified argument type and +increments the va_list to point to the next argument. Again, the +actual type of va_list is target specific.
Semantics:
-The 'vaarg' instruction loads an argument of the specified type from -the specified va_list. In conjunction with the vanext instruction, it is used to implement the -va_arg macro available in C. For more information, see the variable -argument handling Intrinsic Functions.
+The 'va_arg' instruction loads an argument of the specified +type from the specified va_list and causes the +va_list to point to the next argument. For more information, +see the variable argument handling Intrinsic +Functions.
It is legal for this instruction to be called in a function which does not take a variable number of arguments, for example, the vfprintf function.
-vaarg is an LLVM instruction instead of an intrinsic function because it takes an type as an +
va_arg is an LLVM instruction instead of an intrinsic function because it takes a type as an argument.
Example:
@@ -2134,14 +3592,14 @@ argument.@@ -2167,7 +3621,7 @@ understand to raw LLVM instructions that they do.LLVM supports the notion of an "intrinsic function". These functions have -well known names and semantics, and are required to follow certain +well known names and semantics and are required to follow certain restrictions. Overall, these instructions represent an extension mechanism for the LLVM language that does not require changing all of the transformations in LLVM to add to the language (or the bytecode reader/writer, the parser, etc...).
-Intrinsic function names must all start with an "llvm." prefix, this -prefix is reserved in LLVM for intrinsic names, thus functions may not be named +
Intrinsic function names must all start with an "llvm." prefix. This +prefix is reserved in LLVM for intrinsic names; thus, functions may not be named this. Intrinsic functions must always be external functions: you cannot define the body of intrinsic functions. Intrinsic functions may only be used in call or invoke instructions: it is illegal to take the address of an intrinsic @@ -2149,12 +3607,8 @@ function. Additionally, because intrinsic functions are part of the LLVM language, it is required that they all be documented here if any are added.
--Adding an intrinsic to LLVM is straight-forward if it is possible to express the -concept in LLVM directly (ie, code generator support is not _required_). To do -this, extend the default implementation of the IntrinsicLowering class to handle -the intrinsic. Code generators use this class to lower intrinsics they do not -understand to raw LLVM instructions that they do. +
To learn how to add an intrinsic function, please see the Extending LLVM Guide.
@@ -2211,19 +3670,25 @@ int %test(int %X, ...) {Variable argument support is defined in LLVM with the vanext instruction and these three + href="#i_va_arg">va_arg instruction and these three intrinsic functions. These functions are related to the similarly named macros defined in the <stdarg.h> header file.
@@ -2177,29 +3631,34 @@ language reference manual does not define what this type is, so all transformations should be prepared to handle intrinsics with any type used. -This example shows how the vanext +
This example shows how the va_arg instruction and the variable argument handling intrinsic functions are used.
-int %test(int %X, ...) { +define i32 @test(i32 %X, ...) { ; Initialize variable argument processing - %ap = call sbyte* %llvm.va_start() + %ap = alloca i8 * + %ap2 = bitcast i8** %ap to i8* + call void @llvm.va_start(i8* %ap2) ; Read a single integer argument - %tmp = vaarg sbyte* %ap, int - - ; Advance to the next argument - %ap2 = vanext sbyte* %ap, int + %tmp = va_arg i8 ** %ap, i32 ; Demonstrate usage of llvm.va_copy and llvm.va_end - %aq = call sbyte* %llvm.va_copy(sbyte* %ap2) - call void %llvm.va_end(sbyte* %aq) + %aq = alloca i8 * + %aq2 = bitcast i8** %aq to i8* + call void @llvm.va_copy(i8 *%aq2, i8* %ap2) + call void @llvm.va_end(i8* %aq2) ; Stop processing of arguments. - call void %llvm.va_end(sbyte* %ap2) - ret int %tmp + call void @llvm.va_end(i8* %ap2) + ret i32 %tmp } + +declare void @llvm.va_start(i8*) +declare void @llvm.va_copy(i8*, i8*) +declare void @llvm.va_end(i8*)@@ -2233,19 +3698,25 @@ within the body of a variable argument function.Syntax:
-call <va_list> ()* %llvm.va_start()+declare void %llvm.va_start(i8* <arglist>)Overview:
-The 'llvm.va_start' intrinsic returns a new <arglist> -for subsequent use by the variable argument intrinsics.
+The 'llvm.va_start' intrinsic initializes +*<arglist> for subsequent use by va_arg.
+ +Arguments:
+ +The argument is a pointer to a va_list element to initialize.
+Semantics:
-The 'llvm.va_start' intrinsic works just like the va_start -macro available in C. In a target-dependent way, it initializes and -returns a va_list element, so that the next vaarg -will produce the first variable argument passed to the function. Unlike -the C va_start macro, this intrinsic does not need to know the + +
The 'llvm.va_start' intrinsic works just like the va_start +macro available in C. In a target-dependent way, it initializes the +va_list element the argument points to, so that the next call to +va_arg will produce the first variable argument passed to the function. +Unlike the C va_start macro, this intrinsic does not need to know the last argument of the function, the compiler can figure that out.
-Note that this intrinsic function is only legal to be called from -within the body of a variable argument function.
+@@ -2258,24 +3729,26 @@ with calls to llvm.va_end.Syntax:
-call void (<va_list>)* %llvm.va_end(<va_list> <arglist>)+declare void @llvm.va_end(i8* <arglist>)Overview:
+The 'llvm.va_end' intrinsic destroys <arglist> which has been initialized previously with llvm.va_start or llvm.va_copy.
+Arguments:
+The argument is a va_list to destroy.
+Semantics:
+The 'llvm.va_end' intrinsic works just like the va_end macro available in C. In a target-dependent way, it destroys the va_list. Calls to llvm.va_start and llvm.va_copy must be matched exactly with calls to llvm.va_end.
+Syntax:
- call <va_list> (<va_list>)* %llvm.va_copy(<va_list> <destarglist>) + declare void @llvm.va_copy(i8* <destarglist>, i8* <srcarglist>)Overview:
-The 'llvm.va_copy' intrinsic copies the current argument position -from the source argument list to the destination argument list.
+The 'llvm.va_copy' intrinsic copies the current argument position from +the source argument list to the destination argument list.
Arguments:
-The argument is the va_list to copy.
+The first argument is a pointer to a va_list element to initialize. +The second argument is a pointer to a va_list element to copy from.
+Semantics:
-The 'llvm.va_copy' intrinsic works just like the va_copy -macro available in C. In a target-dependent way, it copies the source -va_list element into the returned list. This intrinsic is necessary -because the llvm.va_start intrinsic may be +
The 'llvm.va_copy' intrinsic works just like the va_copy macro +available in C. In a target-dependent way, it copies the source +va_list element into the destination list. This intrinsic is necessary +because the llvm.va_begin intrinsic may be arbitrarily complex and require memory allocation, for example.
Syntax:
- call void (<ty>**, <ty2>*)* %llvm.gcroot(<ty>** %ptrloc, <ty2>* %metadata) + declare void @llvm.gcroot(<ty>** %ptrloc, <ty2>* %metadata)Overview:
@@ -2343,7 +3816,7 @@ the runtime to find the pointer at GC safe points.Syntax:
- call sbyte* (sbyte**)* %llvm.gcread(sbyte** %Ptr) + declare i8 * @llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)Overview:
@@ -2354,8 +3827,10 @@ barriers.Arguments:
-The argument is the address to read from, which should be an address -allocated from the garbage collector.
+The second argument is the address to read from, which should be an address +allocated from the garbage collector. The first object is a pointer to the +start of the referenced object, if needed by the language runtime (otherwise +null).
Semantics:
@@ -2376,7 +3851,7 @@ garbage collector runtime, as needed.Syntax:
- call void (sbyte*, sbyte**)* %llvm.gcwrite(sbyte* %P1, sbyte** %P2) + declare void @llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)Overview:
@@ -2387,8 +3862,10 @@ barriers (such as generational or reference counting collectors).Arguments:
-The first argument is the reference to store, and the second is the heap -location to store to.
+The first argument is the reference to store, the second is the start of the +object to store it to, and the third is the address of the field of Obj to +store to. If the runtime does not require a pointer to the object, Obj may be +null.
Semantics:
@@ -2422,14 +3899,15 @@ be implemented with code generator support.Syntax:
- call void* ()* %llvm.returnaddress(uint <level>) + declare i8 *@llvm.returnaddress(i32 <level>)Overview:
-The 'llvm.returnaddress' intrinsic returns a target-specific value -indicating the return address of the current function or one of its callers. +The 'llvm.returnaddress' intrinsic attempts to compute a +target-specific value indicating the return address of the current function +or one of its callers.
Arguments:
@@ -2466,14 +3944,14 @@ source-language caller.Syntax:
- call void* ()* %llvm.frameaddress(uint <level>) + declare i8 *@llvm.frameaddress(i32 <level>)Overview:
-The 'llvm.frameaddress' intrinsic returns the target-specific frame -pointer value for the specified stack frame. +The 'llvm.frameaddress' intrinsic attempts to return the +target-specific frame pointer value for the specified stack frame.
Arguments:
@@ -2502,238 +3980,185 @@ source-language caller.- - - - - -Syntax:
- call void (sbyte *, uint, uint)* %llvm.prefetch(sbyte * <address>, - uint <rw>, - uint <locality>) + declare i8 *@llvm.stacksave()Overview:
- --The 'llvm.prefetch' intrinsic is a hint to the code generator to insert -a prefetch instruction if supported, otherwise it is a noop. Prefetches have no -effect on the behavior of the program, but can change its performance -characteristics. -
- -Arguments:
--address is the address to be prefetched, rw is the specifier -determining if the fetch should be for a read (0) or write (1), and -locality is a temporal locality specifier ranging from (0) - no -locality, to (3) - exteremely local keep in cache. The rw and -locality arguments must be constant integers. +The 'llvm.stacksave' intrinsic is used to remember the current state of +the function stack, for use with +llvm.stackrestore. This is useful for implementing language +features like scoped automatic variable sized arrays in C99.
Semantics:
-This intrinsic does not modify the behavior of the program. In particular, -prefetches cannot trap and do not produce a value. On targets that support this -intrinsic, the prefetch can provide hints to the processor cache for better -performance. -
- ---These intrinsics are provided by LLVM to support the implementation of -operating system level code. +This intrinsic returns a opaque pointer value that can be passed to llvm.stackrestore. When an +llvm.stackrestore intrinsic is executed with a value saved from +llvm.stacksave, it effectively restores the state of the stack to the +state it was in when the llvm.stacksave intrinsic executed. In +practice, this pops any alloca blocks from the stack +that were allocated after the llvm.stacksave was executed.
+Syntax:
- call <integer type> (<integer type>)* %llvm.readport (<integer type> <address>) + declare void @llvm.stackrestore(i8 * %ptr)Overview:
-The 'llvm.readport' intrinsic reads data from the specified hardware -I/O port. -
- -Arguments:
- --The argument to this intrinsic indicates the hardware I/O address from which -to read the data. The address is in the hardware I/O address namespace (as -opposed to being a memory location for memory mapped I/O). +The 'llvm.stackrestore' intrinsic is used to restore the state of +the function stack to the state it was in when the corresponding llvm.stacksave intrinsic executed. This is +useful for implementing language features like scoped automatic variable sized +arrays in C99.
Semantics:
-The 'llvm.readport' intrinsic reads data from the hardware I/O port -specified by address and returns the value. The address and return -value must be integers, but the size is dependent upon the platform upon which -the program is code generated. For example, on x86, the address must be an -unsigned 16 bit value, and the return value must be 8, 16, or 32 bits. +See the description for llvm.stacksave.
Syntax:
- call void (<integer type>, <integer type>)* - %llvm.writeport (<integer type> <value>, - <integer type> <address>) + declare void @llvm.prefetch(i8 * <address>, + i32 <rw>, i32 <locality>)Overview:
+-The 'llvm.writeport' intrinsic writes data to the specified hardware -I/O port. +The 'llvm.prefetch' intrinsic is a hint to the code generator to insert +a prefetch instruction if supported; otherwise, it is a noop. Prefetches have +no +effect on the behavior of the program but can change its performance +characteristics.
Arguments:
-The first argument is the value to write to the I/O port. -
- --The second argument indicates the hardware I/O address to which data should be -written. The address is in the hardware I/O address namespace (as opposed to -being a memory location for memory mapped I/O). +address is the address to be prefetched, rw is the specifier +determining if the fetch should be for a read (0) or write (1), and +locality is a temporal locality specifier ranging from (0) - no +locality, to (3) - extremely local keep in cache. The rw and +locality arguments must be constant integers.
Semantics:
-The 'llvm.writeport' intrinsic writes value to the I/O port -specified by address. The address and value must be integers, but the -size is dependent upon the platform upon which the program is code generated. -For example, on x86, the address must be an unsigned 16 bit value, and the -value written must be 8, 16, or 32 bits in length. +This intrinsic does not modify the behavior of the program. In particular, +prefetches cannot trap and do not produce a value. On targets that support this +intrinsic, the prefetch can provide hints to the processor cache for better +performance.
Syntax:
- call <result> (<ty>*)* %llvm.readio (<ty> * <pointer>) + declare void @llvm.pcmarker( i32 <id> )Overview:
+-The 'llvm.readio' intrinsic reads data from a memory mapped I/O -address. +The 'llvm.pcmarker' intrinsic is a method to export a Program Counter +(PC) in a region of +code to simulators and other tools. The method is target specific, but it is +expected that the marker will use exported symbols to transmit the PC of the marker. +The marker makes no guarantees that it will remain with any specific instruction +after optimizations. It is possible that the presence of a marker will inhibit +optimizations. The intended use is to be inserted after optimizations to allow +correlations of simulation runs.
Arguments:
-The argument to this intrinsic is a pointer indicating the memory address from -which to read the data. The data must be a -first class type. +id is a numerical id identifying the marker.
Semantics:
-The 'llvm.readio' intrinsic reads data from a memory mapped I/O -location specified by pointer and returns the value. The argument must -be a pointer, and the return value must be a -first class type. However, certain architectures -may not support I/O on all first class types. For example, 32 bit processors -may only support I/O on data types that are 32 bits or less. -
- --This intrinsic enforces an in-order memory model for llvm.readio and -llvm.writeio calls on machines that use dynamic scheduling. Dynamically -scheduled processors may execute loads and stores out of order, re-ordering at -run time accesses to memory mapped I/O registers. Using these intrinsics -ensures that accesses to memory mapped I/O registers occur in program order. +This intrinsic does not modify the behavior of the program. Backends that do not +support this intrinisic may ignore it.
@@ -2762,41 +4187,43 @@ for more efficient code generation.Syntax:
- call void (<ty1>, <ty2>*)* %llvm.writeio (<ty1> <value>, <ty2> * <pointer>) + declare i64 @llvm.readcyclecounter( )Overview:
--The 'llvm.writeio' intrinsic writes data to the specified memory -mapped I/O address. -
- -Arguments:
-The first argument is the value to write to the memory mapped I/O location. -The second argument is a pointer indicating the memory address to which the -data should be written. +The 'llvm.readcyclecounter' intrinsic provides access to the cycle +counter register (or similar low latency, high accuracy clocks) on those targets +that support it. On X86, it should map to RDTSC. On Alpha, it should map to RPCC. +As the backing counters overflow quickly (on the order of 9 seconds on alpha), this +should only be used for small timings.
Semantics:
-The 'llvm.writeio' intrinsic writes value to the memory mapped -I/O address specified by pointer. The value must be a -first class type. However, certain architectures -may not support I/O on all first class types. For example, 32 bit processors -may only support I/O on data types that are 32 bits or less. -
- --This intrinsic enforces an in-order memory model for llvm.readio and -llvm.writeio calls on machines that use dynamic scheduling. Dynamically -scheduled processors may execute loads and stores out of order, re-ordering at -run time accesses to memory mapped I/O registers. Using these intrinsics -ensures that accesses to memory mapped I/O registers occur in program order. +When directly supported, reading the cycle counter should not modify any memory. +Implementations are allowed to either return a application specific value or a +system wide value. On backends without support, this is lowered to a constant 0.
Syntax:
- call void (sbyte*, sbyte*, uint, uint)* %llvm.memcpy(sbyte* <dest>, sbyte* <src>, - uint <len>, uint <align>) + declare void @llvm.memcpy.i32(i8 * <dest>, i8 * <src>, + i32 <len>, i32 <align>) + declare void @llvm.memcpy.i64(i8 * <dest>, i8 * <src>, + i64 <len>, i32 <align>)Overview:
-The 'llvm.memcpy' intrinsic copies a block of memory from the source +The 'llvm.memcpy.*' intrinsics copy a block of memory from the source location to the destination location.
-Note that, unlike the standard libc function, the llvm.memcpy intrinsic -does not return a value, and takes an extra alignment argument. +Note that, unlike the standard libc function, the llvm.memcpy.* +intrinsics do not return a value, and takes an extra alignment argument.
Arguments:
The first argument is a pointer to the destination, the second is a pointer to -the source. The third argument is an (arbitrarily sized) integer argument +the source. The third argument is an integer argument specifying the number of bytes to copy, and the fourth argument is the alignment of the source and destination locations.
If the call to this intrinisic has an alignment value that is not 0 or 1, then -the caller guarantees that the size of the copy is a multiple of the alignment -and that both the source and destination pointers are aligned to that boundary. +the caller guarantees that both the source and destination pointers are aligned +to that boundary.
Semantics:
-The 'llvm.memcpy' intrinsic copies a block of memory from the source +The 'llvm.memcpy.*' intrinsics copy a block of memory from the source location to the destination location, which are not allowed to overlap. It copies "len" bytes of memory over. If the argument is known to be aligned to some boundary, this can be specified as the fourth argument, otherwise it should @@ -2814,42 +4241,44 @@ be set to 0 or 1.
Syntax:
- call void (sbyte*, sbyte*, uint, uint)* %llvm.memmove(sbyte* <dest>, sbyte* <src>, - uint <len>, uint <align>) + declare void @llvm.memmove.i32(i8 * <dest>, i8 * <src>, + i32 <len>, i32 <align>) + declare void @llvm.memmove.i64(i8 * <dest>, i8 * <src>, + i64 <len>, i32 <align>)Overview:
-The 'llvm.memmove' intrinsic moves a block of memory from the source -location to the destination location. It is similar to the 'llvm.memcpy' -intrinsic but allows the two memory locations to overlap. +The 'llvm.memmove.*' intrinsics move a block of memory from the source +location to the destination location. It is similar to the +'llvm.memcmp' intrinsic but allows the two memory locations to overlap.
-Note that, unlike the standard libc function, the llvm.memmove intrinsic -does not return a value, and takes an extra alignment argument. +Note that, unlike the standard libc function, the llvm.memmove.* +intrinsics do not return a value, and takes an extra alignment argument.
Arguments:
The first argument is a pointer to the destination, the second is a pointer to -the source. The third argument is an (arbitrarily sized) integer argument +the source. The third argument is an integer argument specifying the number of bytes to copy, and the fourth argument is the alignment of the source and destination locations.
If the call to this intrinisic has an alignment value that is not 0 or 1, then -the caller guarantees that the size of the copy is a multiple of the alignment -and that both the source and destination pointers are aligned to that boundary. +the caller guarantees that the source and destination pointers are aligned to +that boundary.
Semantics:
-The 'llvm.memmove' intrinsic copies a block of memory from the source +The 'llvm.memmove.*' intrinsics copy a block of memory from the source location to the destination location, which may overlap. It copies "len" bytes of memory over. If the argument is known to be aligned to some boundary, this can be specified as the fourth argument, otherwise it should @@ -2860,21 +4289,23 @@ be set to 0 or 1.
Syntax:
- call void (sbyte*, ubyte, uint, uint)* %llvm.memset(sbyte* <dest>, ubyte <val>, - uint <len>, uint <align>) + declare void @llvm.memset.i32(i8 * <dest>, i8 <val>, + i32 <len>, i32 <align>) + declare void @llvm.memset.i64(i8 * <dest>, i8 <val>, + i64 <len>, i32 <align>)Overview:
-The 'llvm.memset' intrinsic fills a block of memory with a particular +The 'llvm.memset.*' intrinsics fill a block of memory with a particular byte value.
@@ -2887,21 +4318,21 @@ does not return a value, and takes an extra alignment argument.The first argument is a pointer to the destination to fill, the second is the -byte value to fill it with, the third argument is an (arbitrarily sized) integer +byte value to fill it with, the third argument is an integer argument specifying the number of bytes to fill, and the fourth argument is the known alignment of destination location.
If the call to this intrinisic has an alignment value that is not 0 or 1, then -the caller guarantees that the size of the copy is a multiple of the alignment -and that the destination pointer is aligned to that boundary. +the caller guarantees that the destination pointer is aligned to that boundary.
Semantics:
-The 'llvm.memset' intrinsic fills "len" bytes of memory starting at the +The 'llvm.memset.*' intrinsics fill "len" bytes of memory starting at +the destination location. If the argument is known to be aligned to some boundary, this can be specified as the fourth argument, otherwise it should be set to 0 or 1. @@ -2911,40 +4342,237 @@ this can be specified as the fourth argument, otherwise it should be set to 0 or
+ ++ ++ + + + +Syntax:
++ declare float @llvm.sqrt.f32(float %Val) + declare double @llvm.sqrt.f64(double %Val) ++ +Overview:
+ ++The 'llvm.sqrt' intrinsics return the sqrt of the specified operand, +returning the same value as the libm 'sqrt' function would. Unlike +sqrt in libm, however, llvm.sqrt has undefined behavior for +negative numbers (which allows for better optimization). +
+ +Arguments:
+ ++The argument and return value are floating point numbers of the same type. +
+ +Semantics:
+ ++This function returns the sqrt of the specified operand if it is a positive +floating point number. +
++ ++ + + + + +Syntax:
++ declare float @llvm.powi.f32(float %Val, i32 %power) + declare double @llvm.powi.f64(double %Val, i32 %power) ++ +Overview:
+ ++The 'llvm.powi.*' intrinsics return the first operand raised to the +specified (positive or negative) power. The order of evaluation of +multiplications is not defined. +
+ +Arguments:
+ ++The second argument is an integer power, and the first is a value to raise to +that power. +
+ +Semantics:
+ ++This function returns the first value raised to the second power with an +unspecified sequence of rounding operations.
+++ + + + ++LLVM provides intrinsics for a few important bit manipulation operations. +These allow efficient code generation for some algorithms. +
+ ++ ++ + + + +Syntax:
++ declare i16 @llvm.bswap.i16(i16 <id>) + declare i32 @llvm.bswap.i32(i32 <id>) + declare i64 @llvm.bswap.i64(i64 <id>) ++ +Overview:
+ ++The 'llvm.bwsap' family of intrinsics is used to byteswap a 16, 32 or +64 bit quantity. These are useful for performing operations on data that is not +in the target's native byte order. +
+ +Semantics:
+ ++The llvm.bswap.16 intrinsic returns an i16 value that has the high +and low byte of the input i16 swapped. Similarly, the llvm.bswap.i32 +intrinsic returns an i32 value that has the four bytes of the input i32 +swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned +i32 will have its bytes in 3, 2, 1, 0 order. The llvm.bswap.i64 +intrinsic extends this concept to 64 bits. +
+ ++ ++ + +Syntax:
++ declare i8 @llvm.ctpop.i8 (i8 <src>) + declare i16 @llvm.ctpop.i16(i16 <src>) + declare i32 @llvm.ctpop.i32(i32 <src>) + declare i64 @llvm.ctpop.i64(i64 <src>) ++ +Overview:
+ ++The 'llvm.ctpop' family of intrinsics counts the number of bits set in a +value. +
+ +Arguments:
+ ++The only argument is the value to be counted. The argument may be of any +integer type. The return type must match the argument type. +
+ +Semantics:
+ ++The 'llvm.ctpop' intrinsic counts the 1's in a variable. +
++ + + +Syntax:
- call bool (<float or double>, <float or double>)* %llvm.isunordered(<float or double> Val1, - <float or double> Val2) + declare i8 @llvm.ctlz.i8 (i8 <src>) + declare i16 @llvm.ctlz.i16(i16 <src>) + declare i32 @llvm.ctlz.i32(i32 <src>) + declare i64 @llvm.ctlz.i64(i64 <src>)Overview:
-The 'llvm.isunordered' intrinsic returns true if either or both of the -specified floating point values is a NAN. +The 'llvm.ctlz' family of intrinsic functions counts the number of +leading zeros in a variable.
Arguments:
-The arguments are floating point numbers of the same type. +The only argument is the value to be counted. The argument may be of any +integer type. The return type must match the argument type.
Semantics:
-If either or both of the arguments is a SNAN or QNAN, it returns true, otherwise -false. +The 'llvm.ctlz' intrinsic counts the leading (most significant) zeros +in a variable. If the src == 0 then the result is the size in bits of the type +of src. For example, llvm.ctlz(i32 2) = 30.
+ +Syntax:
++ declare i8 @llvm.cttz.i8 (i8 <src>) + declare i16 @llvm.cttz.i16(i16 <src>) + declare i32 @llvm.cttz.i32(i32 <src>) + declare i64 @llvm.cttz.i64(i64 <src>) ++ +Overview:
+ ++The 'llvm.cttz' family of intrinsic functions counts the number of +trailing zeros. +
+ +Arguments:
+ ++The only argument is the value to be counted. The argument may be of any +integer type. The return type must match the argument type. +
+ +Semantics:
+ ++The 'llvm.cttz' intrinsic counts the trailing (least significant) zeros +in a variable. If the src == 0 then the result is the size in bits of the type +of src. For example, llvm.cttz(2) = 1. +
+@@ -2961,6 +4589,19 @@ Debugging document.+ + + +++ +The LLVM exception handling intrinsics (which all start with +llvm.eh. prefix), are described in the LLVM Exception +Handling document.
+
@@ -2970,7 +4611,7 @@ Debugging document. src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /> Chris Lattner
- The LLVM Compiler Infrastructure
+ The LLVM Compiler Infrastructure
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