[all-commits] [llvm/llvm-project] 42febb: StructurizeCFG: simplify phi nodes when possible

[Sameer Sahasrabuddhe via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 42febbab913870ce43ea434f3a58937bf761bb2f
      https://github.com/llvm/llvm-project/commit/42febbab913870ce43ea434f3a58937bf761bb2f
  Author: Sameer Sahasrabuddhe <sameer.sahasrabuddhe at amd.com>
  Date:   2020-03-05 (Thu, 05 Mar 2020)

  Changed paths:
    M llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
    M llvm/test/CodeGen/AMDGPU/loop_break.ll
    M llvm/test/CodeGen/AMDGPU/nested-loop-conditions.ll
    M llvm/test/Transforms/StructurizeCFG/AMDGPU/loop-subregion-misordered.ll

  Log Message:
  -----------
  StructurizeCFG: simplify phi nodes when possible

After structurization, some phi nodes can have a single incoming edge
and can be simplified away. This change runs a simplify query on all
phis that are either modified or added by the structurizer. This also
moves some phis closer to their use as a side benefit.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D75500