[all-commits] [llvm/llvm-project] e585b3: [AMDGPU] PHI node cost should not be counted for t...

[alex-t via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e585b332e42321870b2cf1eeefcd68b0717570e2
      https://github.com/llvm/llvm-project/commit/e585b332e42321870b2cf1eeefcd68b0717570e2
  Author: alex-t <alexander.timofeev at amd.com>
  Date:   2021-06-30 (Wed, 30 Jun 2021)

  Changed paths:
    M llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
    M llvm/test/Analysis/CostModel/AMDGPU/control-flow.ll

  Log Message:
  -----------
  [AMDGPU] PHI node cost should not be counted for the size and latency.

  Details: https://reviews.llvm.org/D96805 changed the GCNTTIImpl::getCFInstrCost to return 1 for the PHI nodes
  for the TTI::TCK_CodeSize and TTI::TCK_SizeAndLatency. This is incorrect because the value moves that are the
  result of the PHI lowering are inserted into the basic block predecessors - not into the block itself.
  As a result of this change LoopRotate and LoopUnroll were broken because of the incorrect Loop header and loop
  body size/cost estimation.

Reviewed By: rampitec

Differential Revision: https://reviews.llvm.org/D105104