[PATCH] D107330: [GlobalISel] Combine shr(shl x, c1), c2 to G_SBFX/G_UBFX

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

LGTM apart from the question inline.



================
Comment at: llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp:4145
+  LLT ExtractTy = getTargetLowering().getPreferredShiftAmountTy(Ty);
+  if (!LI || !LI->isLegalOrCustom({ExtrOpcode, {Ty, ExtractTy}}))
+    return false;
----------------
Lots of combines use `isLegalOrBeforeLegalizer`, i.e. they do apply before legalization. Is there a reason you have made this one different, so it does not apply before legalization?


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https://reviews.llvm.org/D107330