Sema: Factor out clearScore() and replayScore()

Author: slavapestov

include/swift/Sema/ConstraintSystem.h

@@ -5465,6 +5465,15 @@ class ConstraintSystem {
   /// Primitive form of the above. Records a change in the trail.
   void increaseScore(ScoreKind kind, unsigned value);
 
+  /// Apply the score from a partial solution. Records the change in the
+  /// trail.
+  void replayScore(const Score &score);
+
+  /// Temporarily zero out the score, and record this in the trail so that
+  /// we restore the score when the scope ends. Used when solving a
+  /// ConjunctionStep.
+  void clearScore();
+
   /// Determine whether this solution is guaranteed to be worse than the best
   /// solution found so far.
   bool worseThanBestSolution() const;

lib/Sema/CSRanking.cpp

@@ -146,6 +146,27 @@ void ConstraintSystem::increaseScore(ScoreKind kind,
   increaseScore(kind, value);
 }
 
+void ConstraintSystem::replayScore(const Score &score) {
+  if (solverState) {
+    for (unsigned i = 0; i < NumScoreKinds; ++i) {
+      if (unsigned value = score.Data[i])
+        recordChange(
+          SolverTrail::Change::IncreasedScore(ScoreKind(i), value));
+    }
+  }
+  CurrentScore += score;
+}
+
+void ConstraintSystem::clearScore() {
+  for (unsigned i = 0; i < NumScoreKinds; ++i) {
+    if (unsigned value = CurrentScore.Data[i]) {
+      recordChange(
+        SolverTrail::Change::DecreasedScore(ScoreKind(i), value));
+    }
+  }
+  CurrentScore = Score();
+}
+
 bool ConstraintSystem::worseThanBestSolution() const {
   if (getASTContext().TypeCheckerOpts.DisableConstraintSolverPerformanceHacks)
     return false;

lib/Sema/CSSolver.cpp

@@ -271,15 +271,8 @@ Solution ConstraintSystem::finalize() {
 
 void ConstraintSystem::replaySolution(const Solution &solution,
                                       bool shouldIncreaseScore) {
-  if (shouldIncreaseScore) {
-    // Update the score. We do this instead of operator+= because we
-    // want to record the increments in the trail.
-    auto solutionScore = solution.getFixedScore();
-    for (unsigned i = 0; i < NumScoreKinds; ++i) {
-      if (unsigned value = solutionScore.Data[i])
-        increaseScore(ScoreKind(i), value);
-    }
-  }
+  if (shouldIncreaseScore)
+    replayScore(solution.getFixedScore());
 
   // Assign fixed types to the type variables solved by this solution.
   for (auto binding : solution.typeBindings) {

lib/Sema/CSStep.cpp

@@ -885,13 +885,7 @@ bool ConjunctionStep::attempt(const ConjunctionElement &element) {
 
   // Make sure that element is solved in isolation
   // by dropping all scoring information.
-  for (unsigned i = 0; i < NumScoreKinds; ++i) {
-    if (unsigned value = CS.CurrentScore.Data[i]) {
-      CS.recordChange(
-        SolverTrail::Change::DecreasedScore(ScoreKind(i), value));
-    }
-  }
-  CS.CurrentScore = Score();
+  CS.clearScore();
 
   // Reset the scope counter to avoid "too complex" failures
   // when closure has a lot of elements in the body.