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[ConstraintSystem] Some small clean-ups to getFixedType, getFixedTypeRecursive, and simplifyType #18325

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Merged
merged 3 commits into from
Jul 29, 2018
Merged

[ConstraintSystem] Some small clean-ups to getFixedType, getFixedTypeRecursive, and simplifyType #18325

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b900b5d
[ConstraintSystem] Tiny simplification of function.
rudkx Jul 28, 2018
4ac4d42
[ConstraintSystem] Another small simplification.
rudkx Jul 28, 2018
a5da413
[ConstraintSystem] Simplify getFixedTypeRecursive a bit.
rudkx Jul 28, 2018
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69 changes: 30 additions & 39 deletions lib/Sema/ConstraintSystem.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -700,34 +700,41 @@ bool ConstraintSystem::isAnyHashableType(Type type) {
return false;
}

static Type withParens(ConstraintSystem &cs, Type type, ParenType *parenType) {
auto flags = parenType->getParameterFlags().withInOut(type->is<InOutType>());
return ParenType::get(cs.getASTContext(), type->getInOutObjectType(), flags);
}

Type ConstraintSystem::getFixedTypeRecursive(Type type,
TypeMatchOptions &flags,
bool wantRValue,
bool retainParens) {

if (wantRValue)
type = type->getRValueType();
// FIXME: This function doesn't strictly honor retainParens
// everywhere.

if (retainParens) {
if (auto parenTy = dyn_cast<ParenType>(type.getPointer())) {
type = getFixedTypeRecursive(parenTy->getUnderlyingType(), flags,
wantRValue, retainParens);
auto flags = parenTy->getParameterFlags().withInOut(type->is<InOutType>());
return ParenType::get(getASTContext(), type->getInOutObjectType(), flags);
if (wantRValue)
type = type->getRValueType();

if (auto *parenTy = dyn_cast<ParenType>(type.getPointer())) {
auto fixed = getFixedTypeRecursive(parenTy->getUnderlyingType(), flags,
wantRValue, retainParens);
return withParens(*this, fixed, parenTy);
}
}

while (true) {
if (wantRValue)
type = type->getRValueType();

if (auto depMemType = type->getAs<DependentMemberType>()) {
if (!depMemType->getBase()->isTypeVariableOrMember()) return type;

// FIXME: Perform a more limited simplification?
Type newType = simplifyType(type);
if (newType.getPointer() == type.getPointer()) return type;

if (wantRValue)
newType = newType->getRValueType();

type = newType;

// Once we've simplified a dependent member type, we need to generate a
Expand All @@ -736,35 +743,21 @@ Type ConstraintSystem::getFixedTypeRecursive(Type type,
continue;
}

if (auto typeVar = type->getAs<TypeVariableType>()) {
bool hasRepresentative = false;
if (auto *repr = getRepresentative(typeVar)) {
if (typeVar != repr) {
hasRepresentative = true;
typeVar = repr;
}
}

if (auto fixed = getFixedType(typeVar)) {
if (wantRValue)
fixed = fixed->getRValueType();

type = fixed;
continue;
}

// If type variable has a representative but
// no fixed type, reflect that in the type itself.
if (hasRepresentative)
type = typeVar;
auto typeVar = type->getAs<TypeVariableType>();
if (!typeVar)
return type;

break;
if (auto fixed = getFixedType(typeVar)) {
type = fixed;
continue;
}

break;
}
if (retainParens)
if (auto *parenType = dyn_cast<ParenType>(type.getPointer()))
return withParens(*this, getRepresentative(typeVar), parenType);

return type;
return getRepresentative(typeVar);
}
}

/// Does a var or subscript produce an l-value?
Expand Down Expand Up @@ -2022,12 +2015,10 @@ Type ConstraintSystem::simplifyType(Type type) {
return simplifyTypeImpl(
*this, type,
[&](TypeVariableType *tvt) -> Type {
tvt = getRepresentative(tvt);
if (auto fixed = getFixedType(tvt)) {
if (auto fixed = getFixedType(tvt))
return simplifyType(fixed);
}

return tvt;
return getRepresentative(tvt);
});
}

Expand Down
7 changes: 2 additions & 5 deletions lib/Sema/ConstraintSystem.h
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Original file line number Diff line number Diff line change
Expand Up @@ -365,11 +365,8 @@ class TypeVariableType::Implementation {
auto rep = getRepresentative(record);
Implementation &repImpl = rep->getImpl();

// Check whether it has a fixed type.
if (auto type = repImpl.ParentOrFixed.dyn_cast<TypeBase *>())
return type;

return Type();
// Return the bound type if there is one, otherwise, null.
return repImpl.ParentOrFixed.dyn_cast<TypeBase *>();
}

/// \brief Assign a fixed type to this equivalence class.
Expand Down