diff --git a/lib/Target/ARM/ARMTargetTransformInfo.cpp b/lib/Target/ARM/ARMTargetTransformInfo.cpp index 48819335512..13d57c0934a 100644 --- a/lib/Target/ARM/ARMTargetTransformInfo.cpp +++ b/lib/Target/ARM/ARMTargetTransformInfo.cpp @@ -73,6 +73,17 @@ int ARMTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm, // Conversion to BIC is free, and means we can use ~Imm instead. return std::min(getIntImmCost(Imm, Ty), getIntImmCost(~Imm, Ty)); + if (Opcode == Instruction::ICmp && Imm.isNegative() && + Ty->getIntegerBitWidth() == 32) { + int64_t NegImm = -Imm.getSExtValue(); + if (ST->isThumb2() && NegImm < 1<<12) + // icmp X, #-C -> cmn X, #C + return 0; + if (ST->isThumb() && NegImm < 1<<8) + // icmp X, #-C -> adds X, #C + return 0; + } + return getIntImmCost(Imm, Ty); } diff --git a/test/CodeGen/ARM/immcost.ll b/test/CodeGen/ARM/immcost.ll index bfc1fddd3c1..43a4989e6bd 100644 --- a/test/CodeGen/ARM/immcost.ll +++ b/test/CodeGen/ARM/immcost.ll @@ -37,3 +37,37 @@ ret: ret void } +; CHECK: Function: test_icmp_neg +; CHECK-NOT: Collect constant +define void @test_icmp_neg(i1 %cond, i32 %arg, i32 %arg2) { +entry: + %a = icmp ne i32 %arg, -5 + call void @g2(i1 %a) + br i1 %cond, label %true, label %ret + +true: + %b = icmp ne i32 %arg2, -5 + call void @g2(i1 %b) + br label %ret + +ret: + ret void +} +declare void @g2(i1) + +; CHECK: Function: test_icmp_neg2 +; CHECK: Hoist constant (i32 -500) to BB entry +define void @test_icmp_neg2(i1 %cond, i32 %arg, i32 %arg2) { +entry: + %a = icmp ne i32 %arg, -500 + call void @g2(i1 %a) + br i1 %cond, label %true, label %ret + +true: + %b = icmp ne i32 %arg2, -500 + call void @g2(i1 %b) + br label %ret + +ret: + ret void +}