diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -1338,11 +1338,34 @@ if (Instruction *Res = processUGT_ADDCST_ADD(Cmp, A, B, CI2, CI, *this)) return Res; - // icmp(phi(C1, C2, ...), C) -> phi(icmp(C1, C), icmp(C2, C), ...). Constant *C = dyn_cast(Op1); if (!C) return nullptr; + BinaryOperator *BO; + const APInt *LHS, *RHS; + if (match(Op0, m_c_Or(m_BinOp(BO), m_APInt(LHS))) && + match(Op1, m_APInt(RHS))) { + if (LHS->isStrictlyPositive() && RHS->isNonNegative() && LHS->sgt(*RHS)) { + auto Relax = [&](ICmpInst::Predicate Pred, Value *X) { + Value *NewCmp = Builder.CreateICmp( + Pred, X, ConstantInt::getNullValue(X->getType())); + return replaceInstUsesWith(Cmp, NewCmp); + }; + switch (Pred) { + case ICmpInst::ICMP_SLE: + case ICmpInst::ICMP_SLT: + return Relax(ICmpInst::ICMP_SLT, BO); + case ICmpInst::ICMP_SGE: + case ICmpInst::ICMP_SGT: + return Relax(ICmpInst::ICMP_SGE, BO); + default: + break; + } + } + } + + // icmp(phi(C1, C2, ...), C) -> phi(icmp(C1, C), icmp(C2, C), ...). if (auto *Phi = dyn_cast(Op0)) if (all_of(Phi->operands(), [](Value *V) { return isa(V); })) { Type *Ty = Cmp.getType(); diff --git a/llvm/test/Transforms/InstCombine/icmp.ll b/llvm/test/Transforms/InstCombine/icmp.ll --- a/llvm/test/Transforms/InstCombine/icmp.ll +++ b/llvm/test/Transforms/InstCombine/icmp.ll @@ -4631,10 +4631,10 @@ define i1 @mul_add_constant_sgt(i8 %a, i8 %b) { ; CHECK-LABEL: @mul_add_constant_sgt( ; CHECK-NEXT: [[MUL1:%.*]] = mul nsw i8 [[A:%.*]], [[B:%.*]] -; CHECK-NEXT: [[ADD:%.*]] = or i8 [[MUL1]], 24 -; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[ADD]], 0 +; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[MUL1]], -1 ; CHECK-NEXT: ret i1 [[CMP]] ; + %mul1 = mul nsw i8 %a, %b %add = or i8 %mul1, 24 %cmp = icmp sgt i8 %add, 0 @@ -4655,8 +4655,7 @@ define i1 @mul_add_constant_sle(i8 %a, i8 %b) { ; CHECK-LABEL: @mul_add_constant_sle( ; CHECK-NEXT: [[MUL1:%.*]] = mul nsw i8 [[A:%.*]], [[B:%.*]] -; CHECK-NEXT: [[ADD:%.*]] = or i8 [[MUL1]], 24 -; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[ADD]], 1 +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[MUL1]], 0 ; CHECK-NEXT: ret i1 [[CMP]] ; %mul1 = mul nsw i8 %a, %b