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Solver: Keep track of a solution's score as we're computing it.

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No functionality change here; just staging for some future optimizations.


Swift SVN r11028
This commit is contained in:
Doug Gregor
2013-12-09 17:12:07 +00:00
parent ac7ee4ba59
commit 79f8175e0b
8 changed files with 209 additions and 83 deletions
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22
lib/Sema/CSSolver.cpp
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@@ -73,7 +73,7 @@ static Optional<Type> checkTypeOfBinding(ConstraintSystem &cs,
Solution ConstraintSystem::finalize(
FreeTypeVariableBinding allowFreeTypeVariables) {
// Create the solution.
Solution solution(*this);
Solution solution(*this, CurrentScore);
// For any of the type variables that has no associated fixed type, assign a
// fresh generic type parameters.
@@ -123,6 +123,9 @@ Solution ConstraintSystem::finalize(
}
void ConstraintSystem::applySolution(const Solution &solution) {
// Update the score.
CurrentScore += solution.getFixedScore();
// Assign fixed types to the type variables solved by this solution.
llvm::SmallPtrSet<TypeVariableType *, 4>
knownTypeVariables(TypeVariables.begin(), TypeVariables.end());
@@ -134,7 +137,7 @@ void ConstraintSystem::applySolution(const Solution &solution) {
// If we don't already have a fixed type for this type variable,
// assign the fixed type from the solution.
if (!getFixedType(binding.first) && !binding.second->hasTypeVariable())
assignFixedType(binding.first, binding.second);
assignFixedType(binding.first, binding.second, /*updateScore=*/false);
}
// Register overload choices.
@@ -583,6 +586,7 @@ ConstraintSystem::SolverScope::SolverScope(ConstraintSystem &cs)
numConstraintRestrictions = cs.solverState->constraintRestrictions.size();
oldGeneratedConstraints = cs.solverState->generatedConstraints;
cs.solverState->generatedConstraints = &generatedConstraints;
PreviousScore = cs.CurrentScore;
++cs.solverState->NumStatesExplored;
@@ -618,6 +622,9 @@ ConstraintSystem::SolverScope::~SolverScope() {
// Reset the prior generated-constraints pointer.
cs.solverState->generatedConstraints = oldGeneratedConstraints;
// Reset the previous score.
cs.CurrentScore = PreviousScore;
// Clear out other "failed" state.
cs.failedConstraint = nullptr;
}
@@ -932,7 +939,8 @@ bool ConstraintSystem::solve(SmallVectorImpl<Solution> &solutions,
auto solution = finalize(allowFreeTypeVariables);
if (TC.getLangOpts().DebugConstraintSolver) {
auto &log = getASTContext().TypeCheckerDebug->getStream();
log.indent(solverState->depth * 2) << "(found solution)\n";
log.indent(solverState->depth * 2)
<< "(found solution " << CurrentScore << ")\n";
}
solutions.push_back(std::move(solution));
@@ -1069,6 +1077,11 @@ bool ConstraintSystem::solve(SmallVectorImpl<Solution> &solutions,
// Move the type variables back, clear out constraints; we're
// ready for the next component.
TypeVariables = std::move(allTypeVariables);
// For each of the partial solutions, substract off the current score.
// It doesn't contribute.
for (auto &solution : partialSolutions[component])
solution.getFixedScore() -= CurrentScore;
}
// Move the constraints back. The system is back in a normal state.
@@ -1103,7 +1116,8 @@ bool ConstraintSystem::solve(SmallVectorImpl<Solution> &solutions,
auto solution = finalize(allowFreeTypeVariables);
if (TC.getLangOpts().DebugConstraintSolver) {
auto &log = getASTContext().TypeCheckerDebug->getStream();
log.indent(solverState->depth * 2) << "(composed solution)\n";
log.indent(solverState->depth * 2)
<< "(composed solution " << CurrentScore << ")\n";
}
// Save this solution.