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[clang][bytecode] Slightly optimize integral casts of literals #138879

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merged 1 commit into from
May 9, 2025
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[clang][bytecode] Slightly optimize integral casts of literals #138879

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107 changes: 61 additions & 46 deletions clang/lib/AST/ByteCode/Compiler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -238,8 +238,8 @@ bool Compiler<Emitter>::VisitCastExpr(const CastExpr *CE) {
case CK_DerivedToBaseMemberPointer: {
assert(classifyPrim(CE->getType()) == PT_MemberPtr);
assert(classifyPrim(SubExpr->getType()) == PT_MemberPtr);
const auto *FromMP = SubExpr->getType()->getAs<MemberPointerType>();
const auto *ToMP = CE->getType()->getAs<MemberPointerType>();
const auto *FromMP = SubExpr->getType()->castAs<MemberPointerType>();
const auto *ToMP = CE->getType()->castAs<MemberPointerType>();

unsigned DerivedOffset =
Ctx.collectBaseOffset(ToMP->getMostRecentCXXRecordDecl(),
Expand All @@ -254,8 +254,8 @@ bool Compiler<Emitter>::VisitCastExpr(const CastExpr *CE) {
case CK_BaseToDerivedMemberPointer: {
assert(classifyPrim(CE) == PT_MemberPtr);
assert(classifyPrim(SubExpr) == PT_MemberPtr);
const auto *FromMP = SubExpr->getType()->getAs<MemberPointerType>();
const auto *ToMP = CE->getType()->getAs<MemberPointerType>();
const auto *FromMP = SubExpr->getType()->castAs<MemberPointerType>();
const auto *ToMP = CE->getType()->castAs<MemberPointerType>();

unsigned DerivedOffset =
Ctx.collectBaseOffset(FromMP->getMostRecentCXXRecordDecl(),
Expand Down Expand Up @@ -320,37 +320,38 @@ bool Compiler<Emitter>::VisitCastExpr(const CastExpr *CE) {
}

case CK_IntegralToFloating: {
std::optional<PrimType> FromT = classify(SubExpr->getType());
if (!FromT)
if (!CE->getType()->isRealFloatingType())
return false;

if (!this->visit(SubExpr))
return false;

const auto *TargetSemantics = &Ctx.getFloatSemantics(CE->getType());
return this->emitCastIntegralFloating(*FromT, TargetSemantics,
getFPOptions(CE), CE);
return this->emitCastIntegralFloating(
classifyPrim(SubExpr), TargetSemantics, getFPOptions(CE), CE);
}

case CK_FloatingToBoolean:
case CK_FloatingToIntegral: {

std::optional<PrimType> ToT = classify(CE->getType());

if (!ToT)
case CK_FloatingToBoolean: {
if (!SubExpr->getType()->isRealFloatingType() ||
!CE->getType()->isBooleanType())
return false;

if (const auto *FL = dyn_cast<FloatingLiteral>(SubExpr))
return this->emitConstBool(FL->getValue().isNonZero(), CE);
if (!this->visit(SubExpr))
return false;
return this->emitCastFloatingIntegralBool(getFPOptions(CE), CE);
}

case CK_FloatingToIntegral: {
if (!this->visit(SubExpr))
return false;
PrimType ToT = classifyPrim(CE);
if (ToT == PT_IntAP)
return this->emitCastFloatingIntegralAP(Ctx.getBitWidth(CE->getType()),
getFPOptions(CE), CE);
if (ToT == PT_IntAPS)
return this->emitCastFloatingIntegralAPS(Ctx.getBitWidth(CE->getType()),
getFPOptions(CE), CE);

return this->emitCastFloatingIntegral(*ToT, getFPOptions(CE), CE);
return this->emitCastFloatingIntegral(ToT, getFPOptions(CE), CE);
}

case CK_NullToPointer:
Expand Down Expand Up @@ -395,9 +396,7 @@ bool Compiler<Emitter>::VisitCastExpr(const CastExpr *CE) {
case CK_ArrayToPointerDecay: {
if (!this->visit(SubExpr))
return false;
if (!this->emitArrayDecay(CE))
return false;
return true;
return this->emitArrayDecay(CE);
}

case CK_IntegralToPointer: {
Expand Down Expand Up @@ -480,47 +479,63 @@ bool Compiler<Emitter>::VisitCastExpr(const CastExpr *CE) {
return this->emitBuiltinBitCast(CE);

case CK_IntegralToBoolean:
case CK_FixedPointToBoolean:
case CK_FixedPointToBoolean: {
// HLSL uses this to cast to one-element vectors.
std::optional<PrimType> FromT = classify(SubExpr->getType());
if (!FromT)
return false;

if (const auto *IL = dyn_cast<IntegerLiteral>(SubExpr))
return this->emitConst(IL->getValue(), CE);
if (!this->visit(SubExpr))
return false;
return this->emitCast(*FromT, classifyPrim(CE), CE);
}

case CK_BooleanToSignedIntegral:
case CK_IntegralCast: {
std::optional<PrimType> FromT = classify(SubExpr->getType());
std::optional<PrimType> ToT = classify(CE->getType());

if (!FromT || !ToT)
return false;

if (!this->visit(SubExpr))
return false;
// Try to emit a casted known constant value directly.
if (const auto *IL = dyn_cast<IntegerLiteral>(SubExpr)) {
if (ToT != PT_IntAP && ToT != PT_IntAPS && FromT != PT_IntAP &&
FromT != PT_IntAPS && !CE->getType()->isEnumeralType())
return this->emitConst(IL->getValue(), CE);
if (!this->emitConst(IL->getValue(), SubExpr))
return false;
} else {
if (!this->visit(SubExpr))
return false;
}

// Possibly diagnose casts to enum types if the target type does not
// have a fixed size.
if (Ctx.getLangOpts().CPlusPlus && CE->getType()->isEnumeralType()) {
if (const auto *ET = CE->getType().getCanonicalType()->getAs<EnumType>();
ET && !ET->getDecl()->isFixed()) {
if (const auto *ET = CE->getType().getCanonicalType()->castAs<EnumType>();
!ET->getDecl()->isFixed()) {
if (!this->emitCheckEnumValue(*FromT, ET->getDecl(), CE))
return false;
}
}

auto maybeNegate = [&]() -> bool {
if (CE->getCastKind() == CK_BooleanToSignedIntegral)
return this->emitNeg(*ToT, CE);
return true;
};

if (ToT == PT_IntAP)
return this->emitCastAP(*FromT, Ctx.getBitWidth(CE->getType()), CE) &&
maybeNegate();
if (ToT == PT_IntAPS)
return this->emitCastAPS(*FromT, Ctx.getBitWidth(CE->getType()), CE) &&
maybeNegate();

if (FromT == ToT)
return true;
if (!this->emitCast(*FromT, *ToT, CE))
return false;

return maybeNegate();
if (ToT == PT_IntAP) {
if (!this->emitCastAP(*FromT, Ctx.getBitWidth(CE->getType()), CE))
return false;
} else if (ToT == PT_IntAPS) {
if (!this->emitCastAPS(*FromT, Ctx.getBitWidth(CE->getType()), CE))
return false;
} else {
if (FromT == ToT)
return true;
if (!this->emitCast(*FromT, *ToT, CE))
return false;
}
if (CE->getCastKind() == CK_BooleanToSignedIntegral)
return this->emitNeg(*ToT, CE);
return true;
}

case CK_PointerToBoolean:
Expand Down