[all-commits] [llvm/llvm-project] ed299b: [GlobalISel] Optimize ULEB128 usage (#90565)

[Pierre van Houtryve via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ed299b3efd669c02fa37773d1ae49fca3556f729
      https://github.com/llvm/llvm-project/commit/ed299b3efd669c02fa37773d1ae49fca3556f729
  Author: Pierre van Houtryve <pierre.vanhoutryve at amd.com>
  Date:   2024-05-03 (Fri, 03 May 2024)

  Changed paths:
    M llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutor.h
    M llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h
    M llvm/include/llvm/Support/Compiler.h
    M llvm/unittests/CodeGen/GlobalISel/CMakeLists.txt
    A llvm/unittests/CodeGen/GlobalISel/GIMatchTableExecutorTest.cpp
    M llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.cpp

  Log Message:
  -----------
  [GlobalISel] Optimize ULEB128 usage (#90565)

- Remove some cases where ULEB128 isn't needed
- Add a fastDecodeULEB128 tailored for GlobalISel which does unchecked
decoding optimized for the common case, which is 1 byte values. We
rarely have >1 byte Inst IDs, OpIdx, etc. and those are the most common
ULEB users by far.

This specific LEB128 decode function generates almost 2x less
instructions than the generic one.



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