[PATCH] D99032: GlobalISel: Add FoldBinOpIntoSelect combine

[Jessica Paquette via Phabricator via llvm-commits]

paquette added inline comments.


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Comment at: llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp:3365
+  Register RHS = MI.getOperand(2).getReg();
+  MachineInstr *Select = MRI.getVRegDef(MI.getOperand(SelectOperand).getReg());
+
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arsenm wrote:
> paquette wrote:
> > In the match function, you found the G_SELECT using `getOpcodeDef`, which walks through COPY instructions. If that walked through a COPY, I think this will give you the wrong instruction.
> It's theoretically wrong but due to the copy combines, this was unobservably broken
Would adding a testcase which only enables `fold_binop_into_select` make it possible to test?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99032/new/

https://reviews.llvm.org/D99032