[PATCH] D156620: [InstCombine] Improve foldOpIntoPhi() to use isImpliedCondition

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp:1364
+      const Value *RHSOp0 = Ops[0];
+      const Value *RHSOp1 = Ops[1];
+      bool LHSIsTrue = TerminatorBI->getSuccessor(0) == PN->getParent();
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I don't think the RHSOp0, RHSOp1 variables really add value over Ops[0], Ops[1] here.


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Comment at: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp:1365
+      const Value *RHSOp1 = Ops[1];
+      bool LHSIsTrue = TerminatorBI->getSuccessor(0) == PN->getParent();
+      std::optional<bool> ImpliedCond =
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I think your tests currently only cover one of the LHSIsTrue cases. You also need one with successors swapped.


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Comment at: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp:1372
+        NewPhiValues.push_back(
+            ConstantVector::getIntegerValue(I.getType(), Constant));
+        continue;
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You can use `ConstantInt::getBool()` here.


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Comment at: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp:1383
         &I, Ops, SQ.getWithInstruction(InBB->getTerminator()));
     if (NewVal && NewVal != PN && !match(NewVal, m_ConstantExpr())) {
       NewPhiValues.push_back(NewVal);
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Please extract the code above here into a separate function (which does simplifyInstructionWithOperands plus the special icmp case).


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D156620/new/

https://reviews.llvm.org/D156620