[PATCH] D70564: [GlobalISel] LegalizationArtifactCombiner: Fix a bug in tryCombineMerges

[Aditya Nandakumar via Phabricator via llvm-commits]

aditya_nandakumar added inline comments.


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Comment at: llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h:386
+        // Check if the constraints match. If so, replace the register.
+        // Otherwise, build a COPY instruction to avoid losing the constraints.
+        if (MRI.getRegBankOrNull(FromReg) == MRI.getRegBankOrNull(ToReg) &&
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I think we're going to see this pattern multiple places. It would be unfortunate if we replicate this everywhere. I'd rather generate copies always and let the Combiner clean up redundant copies. Alternatively we could make a common function and make sure it's used everywhere (say replaceRegWithNewReg or something).


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  https://reviews.llvm.org/D70564/new/

https://reviews.llvm.org/D70564