diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index f4734461a62..d843842cb3a 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -1512,6 +1512,30 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, return R; break; + case Instruction::Sub: { + ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(0)); + if (!LHSC) break; + const APInt &LHSV = LHSC->getValue(); + + // C1-X <u C2 -> (X|(C2-1)) == C1 + // iff C1 & (C2-1) == C2-1 + // C2 is a power of 2 + if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() && + RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == (RHSV - 1)) + return new ICmpInst(ICmpInst::ICMP_EQ, + Builder->CreateOr(LHSI->getOperand(1), RHSV - 1), + LHSC); + + // C1-X >u C2 -> (X|C2) == C1 + // iff C1 & C2 == C2 + // C2+1 is a power of 2 + if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() && + (RHSV + 1).isPowerOf2() && (LHSV & RHSV) == RHSV) + return new ICmpInst(ICmpInst::ICMP_NE, + Builder->CreateOr(LHSI->getOperand(1), RHSV), LHSC); + break; + } + case Instruction::Add: // Fold: icmp pred (add X, C1), C2 if (!ICI.isEquality()) { @@ -1708,6 +1732,24 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, default: break; } + + // X-C1 <u C2 -> (X & -C2) == C1 + // iff C1 & (C2-1) == 0 + // C2 is a power of 2 + if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() && + RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == 0) + return new ICmpInst(ICmpInst::ICMP_EQ, + Builder->CreateAnd(LHSI->getOperand(0), -RHSV), + ConstantExpr::getNeg(LHSC)); + + // X-C1 >u C2 -> (X & ~C2) == C1 + // iff C1 & C2 == 0 + // C2+1 is a power of 2 + if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() && + (RHSV + 1).isPowerOf2() && (LHSV & RHSV) == 0) + return new ICmpInst(ICmpInst::ICMP_NE, + Builder->CreateAnd(LHSI->getOperand(0), ~RHSV), + ConstantExpr::getNeg(LHSC)); } } return 0; |
