[all-commits] [llvm/llvm-project] 4e9d20: [AMDGPU] Preserve vcc_lo when shrinking V_CNDMASK

[Piotr Sobczak via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 4e9d207117f684a7d74132ef10d1c2a2a043b161
      https://github.com/llvm/llvm-project/commit/4e9d207117f684a7d74132ef10d1c2a2a043b161
  Author: Piotr Sobczak <Piotr.Sobczak at amd.com>
  Date:   2020-08-27 (Thu, 27 Aug 2020)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
    A llvm/test/CodeGen/AMDGPU/shrink-instructions-implicit-vcclo.mir

  Log Message:
  -----------
  [AMDGPU] Preserve vcc_lo when shrinking V_CNDMASK

There is no justification for changing vcc_lo to vcc
when shrinking V_CNDMASK, and such a change could
later confuse live variable analysis.

Make sure the original register is preserved.

Differential Revision: https://reviews.llvm.org/D86541