[all-commits] [llvm/llvm-project] 208332: [AMDGPU] Add Optimize VGPR LiveRange Pass.

[Ruiling, Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 208332de8abf126b6fb5590bea47cd12257bc064
      https://github.com/llvm/llvm-project/commit/208332de8abf126b6fb5590bea47cd12257bc064
  Author: Ruiling Song <ruiling.song at amd.com>
  Date:   2021-06-21 (Mon, 21 Jun 2021)

  Changed paths:
    M llvm/lib/Target/AMDGPU/AMDGPU.h
    M llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
    M llvm/lib/Target/AMDGPU/CMakeLists.txt
    A llvm/lib/Target/AMDGPU/SIOptimizeVGPRLiveRange.cpp
    M llvm/test/CodeGen/AMDGPU/GlobalISel/sdiv.i64.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/srem.i64.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/udiv.i64.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/urem.i64.ll
    M llvm/test/CodeGen/AMDGPU/bypass-div.ll
    M llvm/test/CodeGen/AMDGPU/collapse-endcf.ll
    M llvm/test/CodeGen/AMDGPU/llc-pipeline.ll
    M llvm/test/CodeGen/AMDGPU/sgpr-control-flow.ll
    M llvm/test/CodeGen/AMDGPU/skip-if-dead.ll
    A llvm/test/CodeGen/AMDGPU/vgpr-liverange-ir.ll
    A llvm/test/CodeGen/AMDGPU/vgpr-liverange.ll

  Log Message:
  -----------
  [AMDGPU] Add Optimize VGPR LiveRange Pass.

This pass aims to optimize VGPR live-range in a typical divergent if-else
control flow. For example:

def(a)
if(cond)
  use(a)
  ... // A
else
  use(a)

As AMDGPU access vgpr with respect to active-mask, we can mark `a` as
dead in region A. For details, please refer to the comments in
implementation file.

The pass is enabled by default, the frontend can disable it through
"-amdgpu-opt-vgpr-liverange=false".

Differential Revision: https://reviews.llvm.org/D102212