LLVM Language Reference Manual. Abstract; Introduction. History of docs / @. The LLVM compiler infrastructure project is a “collection of modular and reusable compiler and .. For the full documentation, refer to ^ Stellard, Tom (March 26, ). “[LLVMdev] RFC: R, a new backend for.
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If the global value is an alias, the Summary entry will look like:. This linkage type is only allowed on definitions, not declarations. Free software movement History Open-source software movement Organizations Events. This intrinsic indicates that after this point in the code, the value of the memory pointed to by ptr is dead.
If the cmpxchg is marked as volatilethen the optimizer is not allowed to modify the number or order of execution of this cmpxchg with other volatile operations. The LLVM representation aims to be light-weight and low-level while being expressive, typed, and extensible at the same time. This overrides the ssp function attribute. If a readonly function writes memory visible to the program, or has other side-effects, the behavior is undefined.
The code generator may select special instructions to save cache bandwidth, such as the MOVNT instruction on x A self-reference can be used to create globally unique domain names. That implies that the function has internal linkage and only has one call site, so the original call is dead after inlining. The function type can be thought of as a function signature.
Optionally, the parameter list may include a type There are no constants of type x86mmx. They can also occur when transformations cause uniquing collisions when metadata operands change.
The shuffle mask operand is required to be a constant vector with either constant integer or undef values.
Zero indicates the calling function, one indicates its caller, etc. Parameter attributes are simple keywords that follow the type specified. This is what allows a programmer to represent arrays, functions, pointers, and other useful types. The block of memory pointed to by tramp is filled with target dependent code, turning it into a function. Vector types are used when multiple primitive data are operated in parallel using a single instruction SIMD. For some more insight into how it works, see the getelementptr FAQ.
If op2 is statically or dynamically equal to or larger than the number of bits in op1the result is undefined. They cannot be intermingled. Additionally, the global can placed in a comdat if the target has the necessary support. Attributes in the metadata will be added to both the vectorized and epilogue loop. Pointer or vector of pointers types may only be converted to other pointer or vector of pointers types with this instruction. There are two forms of this instruction, corresponding to a conditional branch and an unconditional branch.
The method is target specific, but it is expected that the marker will use exported symbols to transmit the PC of the marker. This ordering cannot be specified for read-modify-write operations; it is not strong enough to make them atomic in any interesting way.
For a table of how this is implemented in various languages, please see Wikipedia: Metadata can be used as function arguments. If the isvolatile parameter is truethe llvm. The following example defines a thread-local global with the initialexec TLS model:. When link-time optimization is enabled, the compiler generates LLVM bitcode instead of native code, and native code generation is done by the linker.
The inalloca argument attribute allows the caller to take the address of outgoing stack arguments. The optional Refs field looks like:. Currently, loop metadata is implemented as metadata attached to the branch instruction in the loop latch block.
A DIExpresion attached to the intrinsic refines the first operand to produce a direct value. A pointer to an i32 value that resides in address space 5. The first argument is an integer value result of some expressionthe second is a pointer to a global string, the third is a pointer to a global string which is the source file name, and the last argument is the line number.
All records defined inside the braces via def and defm are collected in a globally accessible list of the given name in addition to being added to the global collection of records as usual.
TableGen Language Reference — LLVM 8 documentation
As long as the behavior of an operand bundle is describable within these restrictions, LLVM does not need to have special knowledge of the operand bundle to not miscompile programs containing it. This metadata defines which attributes the isolated loops with unsafe memory dependencies will have.
A store of an undefined value can be assumed to not have any effect; we can assume that the value is overwritten with bits that happen to match what was already there. Note that the size and the alignment are target-specific – LLVM currently provides no portable way of determining them, so a front-end that generates this intrinsic needs to have some target-specific knowledge.
Aggregate Types are a subset of derived types that can contain multiple member types. Any bit width from 1 bit to 2 23 -1 about 8 million can be specified.
Unary operators require a single operand, execute an operation on it, and produce a single value. LLVM supports a lanref instruction set and type system. A module may specify a target specific data layout string that specifies how data is to be laid out in memory.