diff options
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp index ca1885a6128..11b7a165d6e 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp @@ -926,6 +926,12 @@ Instruction *InstCombiner::visitShl(BinaryOperator &I) { // (X * C2) << C1 --> X * (C2 << C1) if (match(Op0, m_Mul(m_Value(X), m_Constant(C2)))) return BinaryOperator::CreateMul(X, ConstantExpr::getShl(C2, C1)); + + // shl (zext i1 X), C1 --> select (X, 1 << C1, 0) + if (match(Op0, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) { + auto *NewC = ConstantExpr::getShl(ConstantInt::get(Ty, 1), C1); + return SelectInst::Create(X, NewC, ConstantInt::getNullValue(Ty)); + } } // (1 << (C - x)) -> ((1 << C) >> x) if C is bitwidth - 1 |
