diff options
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index 95bba3c7af7..9ce1c3fc41b 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -1447,6 +1447,23 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, ICI.getPredicate() == ICmpInst::ICMP_EQ ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_ULE, LHSI->getOperand(0), SubOne(RHS)); + + // (icmp eq (and %A, C), 0) -> (icmp sgt (trunc %A), -1) + // iff C is a power of 2 + if (ICI.isEquality() && LHSI->hasOneUse() && match(RHS, m_Zero())) { + if (auto *CI = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { + const APInt &AI = CI->getValue(); + int32_t ExactLogBase2 = AI.exactLogBase2(); + if (ExactLogBase2 != -1 && DL.isLegalInteger(ExactLogBase2 + 1)) { + Type *NTy = IntegerType::get(ICI.getContext(), ExactLogBase2 + 1); + Value *Trunc = Builder->CreateTrunc(LHSI->getOperand(0), NTy); + return new ICmpInst(ICI.getPredicate() == ICmpInst::ICMP_EQ + ? ICmpInst::ICMP_SGE + : ICmpInst::ICMP_SLT, + Trunc, Constant::getNullValue(NTy)); + } + } + } break; case Instruction::Or: { |
