[LoopRotate] Remove canRotateDeoptimizingLatchExit and multi-rotate (#162482) This patch removes canRotateDeoptimizingLatchExit check from loop roate and connected multi rotation option for loop roate (-loop-rotate-multi option). The heuristic in canRotateDeoptimizingLatchExit returns true if any of the loop exits are non-deoptimizing. This means if the loop has multiple deopt exits, then without multi-rotate, we may still end up having deopt exit at the latch. This multi-rotate option is introduced but it is off by default. We have not seen any improvements downstream as well, where we have frequent number of deoptimizations in IR. Since the original heuristic without the multi-rotate effectively ends up being "rotate under some conditions", but the loop may still not be in the form we want, we should remove the heuristic and multi-rotate framework entirely Note that the diff is big, but it's just removal of while loop and indentation change. After this patch I would like to continue here and propose adding a computability check for exit count, but that will be in a separate PR. Requests for review: @annamthomas @fhahn @davemgreen Co-authored-by: Marek Sedlacek <msedlacek@azul.com>
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.