2330fd2f73
LoopPeel currently considers PHI nodes that become loop invariants
through peeling. However, in some cases, peeling transforms PHI nodes
into induction variables (IVs), potentially enabling further
optimizations such as loop vectorization. For example:
```c
// TSVC s292
int im = N-1;
for (int i=0; i<N; i++) {
a[i] = b[i] + b[im];
im = i;
}
```
In this case, peeling one iteration converts `im` into an IV, allowing
it to be handled by the loop vectorizer.
This patch adds a new feature to peel loops when to convert PHIs into
IVs. At the moment this feature is disabled by default.
Enabling it allows to vectorize the above example. I have measured on
neoverse-v2 and observed a speedup of more than 60% (options: `-O3
-ffast-math -mcpu=neoverse-v2 -mllvm -enable-peeling-for-iv`).
This PR is taken over from #94900
Related #81851
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.