[X86] Correctly call 16 byte atomic helpers on x86_64 Windows (#181356) On x86_64 Windows, i128 values are returned in xmm0, and as arguments to functions, they are passed indirectly (rather than in a GPR pair) - see WinX86_64ABIInfo::classify in Clang [1]. When AtomicExpandPass generates a libcall, it normally generates one with i128 arguments and return types. This type isn't lowered correctly (it ends up passed or returned in a pair of GPRs). To fix this issue, make AtomicExpandPass use the v2i64 type instead of i128 here, just like Clang would do for an explicit function call; this type ends up lowered correctly. This fixes https://github.com/mstorsjo/llvm-mingw/issues/538 and https://github.com/llvm/llvm-project/issues/136428. [1] https://github.com/llvm/llvm-project/blob/llvmorg-21.1.8/clang/lib/CodeGen/Targets/X86.cpp#L3390-L3408
Welcome to the LLVM project!
This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.
The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.
C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.
Other components include: the libc++ C++ standard library, the LLD linker, and more.
Consult the Getting Started with LLVM page for information on building and running LLVM.
For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.
Join the LLVM Discourse forums, Discord chat, LLVM Office Hours or Regular sync-ups.
The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.