[PATCH] D86611: GlobalISel: Combine `op undef, x` to 0

[Volkan Keles via Phabricator via llvm-commits]

volkan added inline comments.


================
Comment at: llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp:1858
+  MachineOperand &MO = MI.getOperand(OpIdx);
+  return MO.isReg() &&
+         getOpcodeDef(TargetOpcode::G_IMPLICIT_DEF, MO.getReg(), MRI);
----------------
arsenm wrote:
> The isReg check should be unnecessary
`MO.getReg()` may cause a crash without that check. This shouldn't a problem for this case, but I'd like to keep it as this function might be used by other combines too.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D86611/new/

https://reviews.llvm.org/D86611