Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp =================================================================== --- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -2971,6 +2971,16 @@ BO0->hasOneUse() && BO1->hasOneUse()) return new ICmpInst(Pred, D, B); + // icmp (0-X) < cst --> x > -cst + if (NoOp0WrapProblem && ICmpInst::isSigned(Pred)) { + Value *X; + if (match(BO0, m_Neg(m_Value(X)))) + if (ConstantInt *RHSC = dyn_cast(Op1)) + if (!RHSC->isMinValue(/*isSigned=*/true)) + return new ICmpInst(I.getSwappedPredicate(), X, + ConstantExpr::getNeg(RHSC)); + } + BinaryOperator *SRem = nullptr; // icmp (srem X, Y), Y if (BO0 && BO0->getOpcode() == Instruction::SRem && Index: llvm/trunk/test/Transforms/InstCombine/icmp.ll =================================================================== --- llvm/trunk/test/Transforms/InstCombine/icmp.ll +++ llvm/trunk/test/Transforms/InstCombine/icmp.ll @@ -1356,3 +1356,12 @@ %z = icmp ne i32 %x, %y ret i1 %z } + +; CHECK-LABEL: @icmp_neg_cst_slt +; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp sgt i32 %a, 10 +; CHECK-NEXT: ret i1 [[CMP]] +define i1 @icmp_neg_cst_slt(i32 %a) { + %1 = sub nsw i32 0, %a + %2 = icmp slt i32 %1, -10 + ret i1 %2 +}