[all-commits] [llvm/llvm-project] 77e513: [CodeGen] Use RegUnits in RegisterClassInfo::getLa...

[Jay Foad via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 77e5136ce4221a9f02e905e6079f01d497cfe79e
      https://github.com/llvm/llvm-project/commit/77e5136ce4221a9f02e905e6079f01d497cfe79e
  Author: Jay Foad <jay.foad at amd.com>
  Date:   2024-01-30 (Tue, 30 Jan 2024)

  Changed paths:
    M llvm/include/llvm/CodeGen/RegisterClassInfo.h
    M llvm/lib/CodeGen/RegisterClassInfo.cpp

  Log Message:
  -----------
  [CodeGen] Use RegUnits in RegisterClassInfo::getLastCalleeSavedAlias (#79996)

Change the implementation of getLastCalleeSavedAlias to use RegUnits
instead of register aliases. This is much faster on targets like AMDGPU
which define a very large number of overlapping register tuples.

No functional change intended. If PhysReg overlaps multiple CSRs then
getLastCalleeSavedAlias(PhysReg) could conceivably return a different
arbitrary one, but currently it is only used for some debug printing
anyway.

Differential Revision: https://reviews.llvm.org/D146734