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Construct the type witnesses of SpecializedProtocolConformance lazily.

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A SpecializedProtocolConformance intentionally contains all of the
information we need to synthesize the type witnesses from the
underlying (generic) conformance. Do so lazily rather than eagerly,
because we won't always need all of them.

As a nice side effect, we no longer need to serialize the witnesses of
these specialized protocol conformances, so we can save some space in
the Swift module file.


Swift SVN r11303
This commit is contained in:
Doug Gregor
2013-12-14 06:20:44 +00:00
parent b26ac34ade
commit 07c0793e30
14 changed files with 84 additions and 151 deletions
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51
lib/AST/ProtocolConformance.cpp
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@@ -16,6 +16,7 @@
#include "swift/AST/ASTContext.h"
#include "swift/AST/ProtocolConformance.h"
#include "swift/AST/Decl.h"
#include "swift/AST/Module.h"
#include "swift/AST/Types.h"
using namespace swift;
@@ -56,8 +57,9 @@ Module *ProtocolConformance::getContainingModule() const {
}
const Substitution &
ProtocolConformance::getTypeWitness(AssociatedTypeDecl *assocType) const {
CONFORMANCE_SUBCLASS_DISPATCH(getTypeWitness, (assocType))
ProtocolConformance::getTypeWitness(AssociatedTypeDecl *assocType,
LazyResolver *resolver) const {
CONFORMANCE_SUBCLASS_DISPATCH(getTypeWitness, (assocType, resolver))
}
ConcreteDeclRef ProtocolConformance::getWitness(ValueDecl *requirement) const {
@@ -96,11 +98,48 @@ GenericParamList *ProtocolConformance::getGenericParams() const {
}
const Substitution &SpecializedProtocolConformance::getTypeWitness(
AssociatedTypeDecl *assocType) const {
/// FIXME: Create these lazily.
AssociatedTypeDecl *assocType,
LazyResolver *resolver) const {
// If we've already created this type witness, return it.
auto known = TypeWitnesses.find(assocType);
assert(known != TypeWitnesses.end());
return known->second;
if (known != TypeWitnesses.end()) {
return known->second;
}
// Otherwise, perform substitutions to create this witness now.
TypeSubstitutionMap substitutionMap;
for (const auto &substitution : GenericSubstitutions) {
substitutionMap[substitution.Archetype] = substitution.Replacement;
}
auto &genericWitness = GenericConformance->getTypeWitness(assocType, resolver);
auto module = getContainingModule();
auto specializedType
= genericWitness.Replacement.subst(module, substitutionMap,
/*ignoreMissing=*/false,
resolver);
// If the type witness was unchanged, just copy it directly.
if (specializedType.getPointer() == genericWitness.Replacement.getPointer()) {
TypeWitnesses[assocType] = genericWitness;
return TypeWitnesses[assocType];
}
// Gather the conformances for the type witness. These should never fail.
SmallVector<ProtocolConformance *, 4> conformances;
auto archetype = genericWitness.Archetype;
for (auto proto : archetype->getConformsTo()) {
auto conforms = module->lookupConformance(specializedType, proto, resolver);
assert(conforms.getInt() == ConformanceKind::Conforms &&
"Improperly checked substitution");
conformances.push_back(conforms.getPointer());
}
// Form the substitution.
auto &ctx = assocType->getASTContext();
TypeWitnesses[assocType] = Substitution{archetype, specializedType,
ctx.AllocateCopy(conformances)};
return TypeWitnesses[assocType];
}
ConcreteDeclRef