Sema: Record synthesized conformances in the trail

Author: slavapestov

include/swift/Sema/CSTrail.def

@@ -45,6 +45,7 @@ LOCATOR_CHANGE(ResolvedOverload, ResolvedOverloads)
 LOCATOR_CHANGE(RecordedImplicitValueConversion, ImplicitValueConversions)
 LOCATOR_CHANGE(RecordedArgumentList, ArgumentLists)
 LOCATOR_CHANGE(RecordedImplicitCallAsFunctionRoot, ImplicitCallAsFunctionRoots)
+LOCATOR_CHANGE(RecordedSynthesizedConformance, SynthesizedConformances)
 
 EXPR_CHANGE(AppliedPropertyWrapper)
 EXPR_CHANGE(RecordedImpliedResult)

include/swift/Sema/ConstraintSystem.h

@@ -1618,7 +1618,7 @@ class Solution {
 
   /// The set of conformances synthesized during solving (i.e. for
   /// ad-hoc distributed `SerializationRequirement` conformances).
-  llvm::MapVector<ConstraintLocator *, ProtocolConformanceRef>
+  llvm::DenseMap<ConstraintLocator *, ProtocolConformanceRef>
       SynthesizedConformances;
 
   /// Record a new argument matching choice for given locator that maps a
@@ -2428,7 +2428,7 @@ class ConstraintSystem {
 
   /// The set of conformances synthesized during solving (i.e. for
   /// ad-hoc distributed `SerializationRequirement` conformances).
-  llvm::MapVector<ConstraintLocator *, ProtocolConformanceRef>
+  llvm::DenseMap<ConstraintLocator *, ProtocolConformanceRef>
       SynthesizedConformances;
 
 private:
@@ -2855,9 +2855,6 @@ class ConstraintSystem {
     /// FIXME: Remove this.
     unsigned numFixes;
 
-    /// The length of \c SynthesizedConformances.
-    unsigned numSynthesizedConformances;
-
     /// The previous score.
     Score PreviousScore;
 
@@ -5064,6 +5061,9 @@ class ConstraintSystem {
                                             ConstraintLocatorBuilder locator,
                                             TypeMatchOptions flags);
 
+  void recordSynthesizedConformance(ConstraintLocator *locator,
+                                    ProtocolConformanceRef conformance);
+
   /// Attempt to simplify the given conformance constraint.
   ///
   /// \param type The type being tested.

lib/Sema/CSSimplify.cpp

@@ -8329,6 +8329,16 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
   return matchExistentialTypes(type, protocol, kind, flags, locator);
 }
 
+void ConstraintSystem::recordSynthesizedConformance(
+                                           ConstraintLocator *locator,
+                                           ProtocolConformanceRef conformance) {
+  bool inserted = SynthesizedConformances.insert({locator, conformance}).second;
+  ASSERT(inserted);
+
+  if (solverState)
+    recordChange(SolverTrail::Change::RecordedSynthesizedConformance(locator));
+}
+
 ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
                                  Type type,
                                  ProtocolDecl *protocol,
@@ -8487,7 +8497,9 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
           ProtocolConformanceRef synthesized(protocol);
           auto witnessLoc = getConstraintLocator(
               locator.getAnchor(), LocatorPathElt::Witness(witness));
-          SynthesizedConformances.insert({witnessLoc, synthesized});
+          // FIXME: Why are we recording the same locator more than once here?
+          if (SynthesizedConformances.count(witnessLoc) == 0)
+            recordSynthesizedConformance(witnessLoc, synthesized);
           return recordConformance(synthesized);
         };
 

lib/Sema/CSSolver.cpp

@@ -460,7 +460,8 @@ void ConstraintSystem::applySolution(const Solution &solution) {
   }
 
   for (auto &synthesized : solution.SynthesizedConformances) {
-    SynthesizedConformances.insert(synthesized);
+    if (SynthesizedConformances.count(synthesized.first) == 0)
+      recordSynthesizedConformance(synthesized.first, synthesized.second);
   }
 
   // Register any fixes produced along this path.
@@ -708,7 +709,6 @@ ConstraintSystem::SolverScope::SolverScope(ConstraintSystem &cs)
 
   numTypeVariables = cs.TypeVariables.size();
   numFixes = cs.Fixes.size();
-  numSynthesizedConformances = cs.SynthesizedConformances.size();
 
   PreviousScore = cs.CurrentScore;
 
@@ -741,9 +741,6 @@ ConstraintSystem::SolverScope::~SolverScope() {
   // constraints introduced by the current scope.
   cs.solverState->rollback(this);
 
-  // Remove any implicitly synthesized conformances.
-  truncate(cs.SynthesizedConformances, numSynthesizedConformances);
-
   // Reset the previous score.
   cs.CurrentScore = PreviousScore;