| commit | e100d2bf9ad89139efe5b3edc441c2c67cc42bf4 | [log] [tgz] |
|---|---|---|
| author | Piotr Fusik <p.fusik@samsung.com> | Fri Apr 11 15:00:40 2025 +0200 |
| committer | GitHub <noreply@github.com> | Fri Apr 11 15:00:40 2025 +0200 |
| tree | 6e2a7d230b62eda5f91b449397408c0a8f75a060 | |
| parent | c12cb0ccbb408c5e65801a6aa5a8e53b8b36c646 [diff] |
[DAGCombiner] Fold subtraction if above a constant threshold to `umin` (#135194)
Like #134235, but with a constant.
It's a pattern in Adler-32 checksum calculation in zlib.
Example:
unsigned adler32_mod(unsigned x) {
return x >= 65521u ? x - 65521u : x;
}
Before, on RISC-V:
lui a1, 16
lui a2, 1048560
addiw a1, a1, -16
sltu a1, a1, a0
negw a1, a1
addi a2, a2, 15
and a1, a1, a2
addw a0, a0, a1
Or, with Zicond:
lui a1, 16
lui a2, 1048560
addiw a1, a1, -16
sltu a1, a1, a0
addi a2, a2, 15
czero.eqz a1, a2, a1
addw a0, a0, a1
After, with Zbb:
lui a1, 1048560
addi a1, a1, 15
addw a1, a0, a1
minu a0, a1, a0
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.