[all-commits] [llvm/llvm-project] e4b4a9: [MCP] Disable BackwardCopyPropagateBlock for copie...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e4b4a939f8852b2d5aab0d5b999890c7ef85be18
      https://github.com/llvm/llvm-project/commit/e4b4a939f8852b2d5aab0d5b999890c7ef85be18
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2025-05-08 (Thu, 08 May 2025)

  Changed paths:
    M llvm/lib/CodeGen/MachineCopyPropagation.cpp
    A llvm/test/CodeGen/SystemZ/pr137687.mir

  Log Message:
  -----------
  [MCP] Disable BackwardCopyPropagateBlock for copies with implicit registers. (#137687)

If there's an implicit-def of a super register, the propagation
must preserve this implicit-def. Knowing how and when to do this
may require target specific knowledge so just disable it for now.
    
Prior to 2def1c4, we checked that the copy had explicit 2 operands
when that was removed we started allowing implicit operands through.
This patch adds a check for implicit operands, but still allows
extra explicit operands which was the goal of 2def1c4.
    
Fixes #131478.



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