Fix invalid cast in instcombine UMul/ZExt idiom
Fixes https://bugs.llvm.org/show_bug.cgi?id=25454
Do not assume IRBuilder creates Instruction where it can create Value.
Do not assume idiom operands are constant, leave generalisation ot the IRBuilder.
Differential Revision: https://reviews.llvm.org/D35114
llvm-svn: 307554
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 4dae491..60d1cde 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3856,17 +3856,18 @@
} else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
assert(BO->getOpcode() == Instruction::And);
// Replace (mul & mask) --> zext (mul.with.overflow & short_mask)
- ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));
- APInt ShortMask = CI->getValue().trunc(MulWidth);
+ Value *ShortMask =
+ Builder.CreateTrunc(BO->getOperand(1), Builder.getIntNTy(MulWidth));
Value *ShortAnd = Builder.CreateAnd(Mul, ShortMask);
- Instruction *Zext =
- cast<Instruction>(Builder.CreateZExt(ShortAnd, BO->getType()));
- IC.Worklist.Add(Zext);
+ Value *Zext = Builder.CreateZExt(ShortAnd, BO->getType());
+ if (auto *ZextI = dyn_cast<Instruction>(Zext))
+ IC.Worklist.Add(ZextI);
IC.replaceInstUsesWith(*BO, Zext);
} else {
llvm_unreachable("Unexpected Binary operation");
}
- IC.Worklist.Add(cast<Instruction>(U));
+ if (auto *UI = dyn_cast<Instruction>(U))
+ IC.Worklist.Add(UI);
}
}
if (isa<Instruction>(OtherVal))