[PATCH] D63812: [InstCombine] Shift amount reassociation (PR42391)

[Nikita Popov via Phabricator via llvm-commits]

nikic accepted this revision.
nikic added a comment.
This revision is now accepted and ready to land.

LGTM



================
Comment at: lib/Transforms/InstCombine/InstCombineShifts.cpp:37
+    return nullptr;
+  auto *Sh1 = cast<BinaryOperator>(Sh1Value);
+
----------------
Personally I'd prefer `auto *Sh1 = cast<BinaryOperator>(Sh0->getOperand(0))` over the use of `m_CombineAnd()` here, which makes the match less straightforward.


================
Comment at: lib/Transforms/InstCombine/InstCombineShifts.cpp:41
+  Instruction::BinaryOps ShiftOpcode = Sh0->getOpcode();
+  if (ShiftOpcode != cast<Instruction>(Sh0->getOperand(0))->getOpcode())
+    return nullptr;
----------------
Can replace `cast<Instruction>(Sh0->getOperand(0))` with `Sh1` here.


Repository:
  rL LLVM

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  https://reviews.llvm.org/D63812/new/

https://reviews.llvm.org/D63812