[PATCH] D119645: [Transforms] Fix a cast to Instruction if CreateLShr() returns a constant

[Dmitry Vassiliev via Phabricator via llvm-commits]

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When X is a constant, CreateLShr() returns a constant instead of an instruction.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D119645

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp


Index: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -3677,9 +3677,12 @@
       APInt FoldConst = C1->getValue().lshr(C2->getValue());
       FoldConst ^= C3->getValue();
       // Prepare the two operands.
-      auto *Opnd0 = cast<Instruction>(Builder.CreateLShr(X, C2));
+      Value *Opnd0 = Builder.CreateLShr(X, C2);
       Opnd0->takeName(cast<Instruction>(Op0));
-      Opnd0->setDebugLoc(I.getDebugLoc());
+      // When X is a constant, CreateLShr() returns a constant instead
+      // of an instruction.
+      if (Instruction *Opnd0Inst = dyn_cast<Instruction>(Opnd0))
+        Opnd0Inst->setDebugLoc(I.getDebugLoc());
       return BinaryOperator::CreateXor(Opnd0, ConstantInt::get(Ty, FoldConst));
     }
   }


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