[all-commits] [llvm/llvm-project] 45ec3a: [PowerPC] Fix for excessive ACC copies due to PHI ...

[bsaleil via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 45ec3a37b0a54e34e8f47cdac2be495838f93675
      https://github.com/llvm/llvm-project/commit/45ec3a37b0a54e34e8f47cdac2be495838f93675
  Author: Baptiste Saleil <baptiste.saleil at ibm.com>
  Date:   2020-12-03 (Thu, 03 Dec 2020)

  Changed paths:
    M llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
    A llvm/test/CodeGen/PowerPC/mma-phi-accs.ll
    A llvm/test/CodeGen/PowerPC/peephole-phi-acc.mir

  Log Message:
  -----------
  [PowerPC] Fix for excessive ACC copies due to PHI nodes

When using accumulators in loops, they are passed around in PHI nodes of unprimed
accumulators, causing the generation of additional prime/unprime instructions.
This patch detects these cases and changes these PHI nodes to primed accumulator
PHI nodes. We also add IR and MIR test cases for several PHI node cases.

Differential Revision: https://reviews.llvm.org/D91391