[PATCH] D65380: [InstCombine] Shift amount reassociation: shl-trunc-shl pattern

Mon Jul 29 07:37:06 PDT 2019

xbolva00 added inline comments.

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Comment at: llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp:32
+                                             InstCombiner::BuilderTy &Builder) {
+  // Look for:  (Sh0Op0 (???)) shiftopcode ShAmt0
+  Instruction *Sh0Op0;
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Is “???” something common in this codebase? I haven’t seen it yet.

Personally I think the code gives better idea what is going on than currently the comment - (Sh0Op0 (???)) is confusing for me.

What do you think?

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Comment at: llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp:78
+                                 X->getType()->getScalarSizeInBits()))))
+    return nullptr; // FIXME; could perform constant-folding.
+
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FIXME:

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65380/new/

https://reviews.llvm.org/D65380