diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index d04eb35f8a96bf..7fd2553b079642 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -7347,12 +7347,34 @@ ScalarEvolution::getOperandsToCreate(Value *V, SmallVectorImpl &Ops) { // Keep constructing SCEVs' for phis recursively for now. return nullptr; - case Instruction::Select: + case Instruction::Select: { + // Check if U is a select that can be simplified to a SCEVUnknown. + auto CanSimplifyToUnknown = [this, U]() { + if (U->getType()->isIntegerTy(1) || isa(U->getOperand(0))) + return false; + + auto *ICI = dyn_cast(U->getOperand(0)); + if (!ICI) + return false; + Value *LHS = ICI->getOperand(0); + Value *RHS = ICI->getOperand(1); + if (ICI->getPredicate() == CmpInst::ICMP_EQ || + ICI->getPredicate() == CmpInst::ICMP_NE) { + if (!(isa(RHS) && cast(RHS)->isZero())) + return true; + } else if (getTypeSizeInBits(LHS->getType()) > + getTypeSizeInBits(U->getType())) + return true; + return false; + }; + if (CanSimplifyToUnknown()) + return getUnknown(U); + for (Value *Inc : U->operands()) Ops.push_back(Inc); return nullptr; break; - + } case Instruction::Call: case Instruction::Invoke: if (Value *RV = cast(U)->getReturnedArgOperand()) {