[all-commits] [llvm/llvm-project] 831457: [AMDGPU][GlobalISel] Eliminate barrier if workgrou...

[jayfoad via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 831457c6d59edb0e381917b35ca6099f9b86c6e8
      https://github.com/llvm/llvm-project/commit/831457c6d59edb0e381917b35ca6099f9b86c6e8
  Author: Jay Foad <jay.foad at amd.com>
  Date:   2020-08-26 (Wed, 26 Aug 2020)

  Changed paths:
    M llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
    M llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.h
    M llvm/test/CodeGen/AMDGPU/barrier-elimination.ll

  Log Message:
  -----------
  [AMDGPU][GlobalISel] Eliminate barrier if workgroup size is not greater than wavefront size

If a workgroup size is known to be not greater than wavefront size
the s_barrier instruction is not needed since all threads are guaranteed
to come to the same point at the same time.

This is the same optimization that was implemented for SelectionDAG in
D31731.

Differential Revision: https://reviews.llvm.org/D86609