[ConstraintSystem] NFC: Define {activate, deactivate}Constraint to make that logic reusable

Author: xedin

lib/Sema/CSSolver.cpp

@@ -251,8 +251,7 @@ bool ConstraintSystem::simplify(bool ContinueAfterFailures) {
   while (!ActiveConstraints.empty()) {
     // Grab the next constraint from the worklist.
     auto *constraint = &ActiveConstraints.front();
-    ActiveConstraints.pop_front();
-    assert(constraint->isActive() && "Worklist constraint is not active?");
+    deactivateConstraint(constraint);
 
     // Simplify this constraint.
     switch (simplifyConstraint(*constraint)) {
@@ -269,36 +268,21 @@ bool ConstraintSystem::simplify(bool ContinueAfterFailures) {
         log << ")\n";
       }
 
-      if (solverState)
-        solverState->retireConstraint(constraint);
-
-      CG.removeConstraint(constraint);
+      retireConstraint(constraint);
       break;
 
     case SolutionKind::Solved:
-      if (solverState) {
+      if (solverState)
         ++solverState->NumSimplifiedConstraints;
-
-        // This constraint has already been solved; retire it.
-        solverState->retireConstraint(constraint);
-      }
-
-      // Remove the constraint from the constraint graph.
-      CG.removeConstraint(constraint);
+      retireConstraint(constraint);
       break;
 
     case SolutionKind::Unsolved:
       if (solverState)
         ++solverState->NumUnsimplifiedConstraints;
-
-      InactiveConstraints.push_back(constraint);
       break;
     }
 
-    // This constraint is not active. We delay this operation until
-    // after simplification to avoid re-insertion.
-    constraint->setActive(false);
-
     // Check whether a constraint failed. If so, we're done.
     if (failedConstraint && !ContinueAfterFailures) {
       return true;
@@ -388,10 +372,7 @@ ConstraintSystem::SolverState::~SolverState() {
 #endif
 
     // Transfer the constraint to "active" set.
-    CS.ActiveConstraints.splice(CS.ActiveConstraints.end(),
-                                CS.InactiveConstraints, constraint);
-
-    constraint->setActive(true);
+    CS.activateConstraint(constraint);
   }
 
   // Restore debugging state.

lib/Sema/ConstraintSystem.cpp

@@ -227,11 +227,8 @@ void ConstraintSystem::addTypeVariableConstraintsToWorkList(
       [](Constraint *constraint) { return !constraint->isActive(); });
 
   // Add any constraints that aren't already active to the worklist.
-  for (auto constraint : inactiveConstraints) {
-    ActiveConstraints.splice(ActiveConstraints.end(), InactiveConstraints,
-                             constraint);
-    constraint->setActive(true);
-  }
+  for (auto *constraint : inactiveConstraints)
+    activateConstraint(constraint);
 }
 
 /// Retrieve a dynamic result signature for the given declaration.

lib/Sema/ConstraintSystem.h

@@ -1996,6 +1996,28 @@ class ConstraintSystem {
       solverState->retireConstraint(constraint);
   }
 
+  /// Transfer given constraint from to active list
+  /// for solver to attempt its simplification.
+  void activateConstraint(Constraint *constraint) {
+    assert(!constraint->isActive() && "Constraint is already active");
+    ActiveConstraints.splice(ActiveConstraints.end(), InactiveConstraints,
+                             constraint);
+    constraint->setActive(true);
+  }
+
+  void deactivateConstraint(Constraint *constraint) {
+    assert(constraint->isActive() && "Constraint is already inactive");
+    InactiveConstraints.splice(InactiveConstraints.end(),
+                               ActiveConstraints, constraint);
+    constraint->setActive(false);
+  }
+
+  void retireConstraint(Constraint *constraint) {
+    if (constraint->isActive())
+      deactivateConstraint(constraint);
+    removeInactiveConstraint(constraint);
+  }
+
   /// Retrieve the list of inactive constraints.
   ConstraintList &getConstraints() { return InactiveConstraints; }