b830bcfde3
Fixes #182677 The `BFE_I32` case in `ComputeNumSignBitsForTargetNode` was not masking the width operand with `& 0x1f`, unlike other BFE operations in the same file. Since the hardware instruction only uses the low 5 bits of the width field, values >= 32 passed via `@llvm.amdgcn.sbfe.i32` caused unsigned integer underflow in the calculation: unsigned SignBits = 32 - Width->getZExtValue() + 1; When width > 33, this underflows, producing incorrect SignBits values. When width == 33, SignBits becomes 0, violating the expected return range of [1, BitWidth]. This led to assertion failures and miscompilation where subsequent BFE narrowing operations were incorrectly eliminated. This patch: - Masks the width value with `& 0x1f` to match hardware behavior - Handles width == 0 (after masking) by returning 32 sign bits - Adds regression tests for width values >= 32
The LLVM Compiler Infrastructure
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.
Getting the Source Code and Building LLVM
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.
Getting in touch
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.