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Constraint graph operations: merging nodes, removing nodes, binding type variables

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Swift SVN r10912
This commit is contained in:
Doug Gregor
2013-12-06 05:02:56 +00:00
parent b3b50b0997
commit 5f928ef40b
2 changed files with 87 additions and 17 deletions
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84
lib/Sema/ConstraintGraph.cpp
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@@ -122,23 +122,11 @@ ConstraintGraph::lookupNode(TypeVariableType *typeVar) {
auto typeVarRep = CS.getRepresentative(typeVar);
if (typeVar != typeVarRep)
(*this)[typeVarRep].addToEquivalenceClass(typeVar);
else {
// If this type variable has a fixed type binding that involves other
// type variables, notify those type variables.
if (auto fixed = CS.getFixedType(typeVarRep)) {
if (fixed->hasTypeVariable()) {
SmallVector<TypeVariableType *, 4> typeVars;
llvm::SmallPtrSet<TypeVariableType *, 4> knownTypeVars;
fixed->getTypeVariables(typeVars);
for (auto otherTypeVar : typeVars) {
if (knownTypeVars.insert(otherTypeVar)) {
(*this)[otherTypeVar].addFixedBinding(typeVar);
stored.NodePtr->addFixedBinding(otherTypeVar);
}
}
}
}
else if (auto fixed = CS.getFixedType(typeVarRep)) {
// Bind the type variable.
bindTypeVariable(typeVar, fixed);
}
return { *stored.NodePtr, stored.Index };
}
@@ -255,12 +243,21 @@ ConstraintGraph::Node::addToEquivalenceClass(TypeVariableType *otherTypeVar) {
assert(TypeVar == TypeVar->getImpl().getRepresentative(nullptr) &&
"Can't extend equivalence class of non-representative type var");
assert(TypeVar == otherTypeVar->getImpl().getRepresentative(nullptr) &&
"Type variables are equivalent");
"Type variables are not equivalent");
if (EquivalenceClass.empty())
EquivalenceClass.push_back(TypeVar);
EquivalenceClass.push_back(otherTypeVar);
}
void ConstraintGraph::Node::addToEquivalenceClass(
ArrayRef<TypeVariableType *> typeVars) {
assert(TypeVar == TypeVar->getImpl().getRepresentative(nullptr) &&
"Can't extend equivalence class of non-representative type var");
if (EquivalenceClass.empty())
EquivalenceClass.push_back(TypeVar);
EquivalenceClass.append(typeVars.begin(), typeVars.end());
}
void ConstraintGraph::Node::addFixedBinding(TypeVariableType *typeVar) {
auto &adjacency = getAdjacency(typeVar);
@@ -278,6 +275,23 @@ void ConstraintGraph::Node::removeFixedBinding(TypeVariableType *typeVar) {
#pragma mark Graph mutation
void ConstraintGraph::removeNode(TypeVariableType *typeVar) {
// Find the node to remove.
auto pos = Nodes.find(typeVar);
assert(pos != Nodes.end() && "No node for this type variable");
// Remove this node.
unsigned index = pos->second.Index;
delete pos->second.NodePtr;
Nodes.erase(pos);
// Remove this type variable from the list.
unsigned lastIndex = TypeVariables.size()-1;
if (index < lastIndex)
TypeVariables[index] = TypeVariables[lastIndex];
TypeVariables.pop_back();
}
void ConstraintGraph::addConstraint(Constraint *constraint) {
// Gather the set of type variables referenced by this constraint.
SmallVector<TypeVariableType *, 8> referencedTypeVars;
@@ -328,6 +342,42 @@ void ConstraintGraph::removeConstraint(Constraint *constraint) {
}
}
void ConstraintGraph::mergeNodes(TypeVariableType *typeVar1,
TypeVariableType *typeVar2) {
assert(CS.getRepresentative(typeVar1) == CS.getRepresentative(typeVar2) &&
"type representatives don't match");
// Retrieve the node for the representative that we're merging into.
auto typeVarRep = CS.getRepresentative(typeVar1);
auto &repNode = (*this)[typeVarRep];
// Retrieve the node for the non-representative.
assert((typeVar1 == typeVarRep || typeVar2 == typeVarRep) &&
"neither type variable is the new representative?");
auto typeVarNonRep = typeVar1 == typeVarRep? typeVar2 : typeVar1;
// Merge equivalence class from the non-representative type variable.
repNode.addToEquivalenceClass((*this)[typeVarNonRep].getEquivalenceClass());
}
void ConstraintGraph::bindTypeVariable(TypeVariableType *typeVar, Type fixed) {
// If there are no type variables in the fixed type, there's nothing to do.
if (!fixed->hasTypeVariable())
return;
SmallVector<TypeVariableType *, 4> typeVars;
llvm::SmallPtrSet<TypeVariableType *, 4> knownTypeVars;
fixed->getTypeVariables(typeVars);
Node &node = (*this)[typeVar];
for (auto otherTypeVar : typeVars) {
if (knownTypeVars.insert(otherTypeVar)) {
(*this)[otherTypeVar].addFixedBinding(typeVar);
node.addFixedBinding(otherTypeVar);
}
}
}
#pragma mark Algorithms
/// Depth-first search for connected components