diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index c6233a68847d..2f1325e80d2f 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -216,7 +216,11 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) { // Replace X*(2^C) with X << C, where C is either a scalar or a vector. - if (Constant *NewCst = getLogBase2(NewOp->getType(), C1)) { + // Note that we need to sanitize undef multipliers to 1, + // to avoid introducing poison. + Constant *SafeC1 = Constant::replaceUndefsWith( + C1, ConstantInt::get(C1->getType()->getScalarType(), 1)); + if (Constant *NewCst = getLogBase2(NewOp->getType(), SafeC1)) { BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst); if (I.hasNoUnsignedWrap()) |