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[ARM][CostModel] CodeSize costs for i1 arith ops

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When optimising for size, make the cost of i1 logical operations
relatively expensive so that optimisations don't try to combine
predicates.

Differential Revision: https://reviews.llvm.org/D86525
This commit is contained in:
Sam Parker 2020-08-25 12:17:24 +01:00
parent 5f500e98a4
commit c37b434c46
2 changed files with 19 additions and 4 deletions
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17
lib/Target/ARM/ARMTargetTransformInfo.cpp
View File

@ -1039,13 +1039,28 @@ int ARMTTIImpl::getArithmeticInstrCost(unsigned Opcode, Type *Ty,
TTI::OperandValueProperties Opd2PropInfo,
ArrayRef<const Value *> Args,
const Instruction *CxtI) {
int ISDOpcode = TLI->InstructionOpcodeToISD(Opcode);
if (ST->isThumb() && CostKind == TTI::TCK_CodeSize && Ty->isIntegerTy(1)) {
// Make operations on i1 relatively expensive as this often involves
// combining predicates. AND and XOR should be easier to handle with IT
// blocks.
switch (ISDOpcode) {
default:
break;
case ISD::AND:
case ISD::XOR:
return 2;
case ISD::OR:
return 3;
}
}
// TODO: Handle more cost kinds.
if (CostKind != TTI::TCK_RecipThroughput)
return BaseT::getArithmeticInstrCost(Opcode, Ty, CostKind, Op1Info,
Op2Info, Opd1PropInfo,
Opd2PropInfo, Args, CxtI);
int ISDOpcode = TLI->InstructionOpcodeToISD(Opcode);
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Ty);
if (ST->hasNEON()) {

6
test/Analysis/CostModel/ARM/arith.ll
View File

@ -63,9 +63,9 @@ define void @i1() {
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %f = ashr i1 undef, undef
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %g = lshr i1 undef, undef
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %h = shl i1 undef, undef
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %i = and i1 undef, undef
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %j = or i1 undef, undef
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %k = xor i1 undef, undef
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %i = and i1 undef, undef
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 3 for instruction: %j = or i1 undef, undef
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %k = xor i1 undef, undef
; CHECK-MVE-SIZE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: ret void
;
%c = add i1 undef, undef