[llvm] abbd684 - [InstCombine] Avoid ConstantExpr::get() in phi binop fold

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2022-07-04T16:46:27+02:00
New Revision: abbd684c02c777aa8cdf992cc3a73e3ca356518b

URL: https://github.com/llvm/llvm-project/commit/abbd684c02c777aa8cdf992cc3a73e3ca356518b
DIFF: https://github.com/llvm/llvm-project/commit/abbd684c02c777aa8cdf992cc3a73e3ca356518b.diff

LOG: [InstCombine] Avoid ConstantExpr::get() in phi binop fold

Use ConstantFoldBinaryOpOperands() instead, in preparation for not
all binops having a supported constant expression.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 0816a4a575d9c..03358150d733e 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1324,6 +1324,11 @@ Instruction *InstCombinerImpl::foldBinopWithPhiOperands(BinaryOperator &BO) {
     if (!isGuaranteedToTransferExecutionToSuccessor(&*BBIter))
       return nullptr;
 
+  // Fold constants for the predecessor block with constant incoming values.
+  Constant *NewC = ConstantFoldBinaryOpOperands(BO.getOpcode(), C0, C1, DL);
+  if (!NewC)
+    return nullptr;
+
   // Make a new binop in the predecessor block with the non-constant incoming
   // values.
   Builder.SetInsertPoint(PredBlockBranch);
@@ -1333,9 +1338,6 @@ Instruction *InstCombinerImpl::foldBinopWithPhiOperands(BinaryOperator &BO) {
   if (auto *NotFoldedNewBO = dyn_cast<BinaryOperator>(NewBO))
     NotFoldedNewBO->copyIRFlags(&BO);
 
-  // Fold constants for the predecessor block with constant incoming values.
-  Constant *NewC = ConstantExpr::get(BO.getOpcode(), C0, C1);
-
   // Replace the binop with a phi of the new values. The old phis are dead.
   PHINode *NewPhi = PHINode::Create(BO.getType(), 2);
   NewPhi->addIncoming(NewBO, OtherBB);