c587c24db5
Back-ports additional tests (eb9febb4a6b0, dc697de12792), refactoring (43c9c14577db) and functional change (18f1369297f4) in a single PR. https://github.com/llvm/llvm-project/pull/114990 allowed more aggressive tail duplication for computed-gotos in both pre- and post-regalloc tail duplication. In some cases, performing tail-duplication too early can lead to worse results, especially if we duplicate blocks with a number of phi nodes. This is causing a ~3% performance regression in some workloads using Python 3.12. This patch updates TailDup to delay aggressive tail-duplication for computed gotos to after register allocation. This means we can keep the non-duplicated version for a bit longer throughout the backend, which should reduce compile-time as well as allowing a number of optimizations and simplifications to trigger before drastically expanding the CFG. For the case in https://github.com/llvm/llvm-project/issues/106846, I get the same performance with and without this patch on Skylake. PR: https://github.com/llvm/llvm-project/pull/150911
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.