RequirementMachine: Mark associated type introduction rules permanent

Author: slavapestov

lib/AST/RequirementMachine/RequirementMachine.cpp

@@ -33,7 +33,8 @@ struct RewriteSystemBuilder {
   bool Dump;
 
   ProtocolGraph Protocols;
-  std::vector<std::pair<MutableTerm, MutableTerm>> Rules;
+  std::vector<std::pair<MutableTerm, MutableTerm>> AssociatedTypeRules;
+  std::vector<std::pair<MutableTerm, MutableTerm>> RequirementRules;
 
   CanType getConcreteSubstitutionSchema(CanType concreteType,
                                         const ProtocolDecl *proto,
@@ -126,7 +127,7 @@ void RewriteSystemBuilder::addAssociatedType(const AssociatedTypeDecl *type,
   MutableTerm rhs;
   rhs.add(Symbol::forAssociatedType(proto, type->getName(), Context));
 
-  Rules.emplace_back(lhs, rhs);
+  AssociatedTypeRules.emplace_back(lhs, rhs);
 }
 
 /// Lowers a generic requirement to a rewrite rule.
@@ -187,7 +188,7 @@ void RewriteSystemBuilder::addRequirement(const Requirement &req,
     constraintTerm = subjectTerm;
     constraintTerm.add(Symbol::forSuperclass(otherType, substitutions,
                                              Context));
-    Rules.emplace_back(subjectTerm, constraintTerm);
+    RequirementRules.emplace_back(subjectTerm, constraintTerm);
 
     constraintTerm = subjectTerm;
     auto layout =
@@ -233,7 +234,7 @@ void RewriteSystemBuilder::addRequirement(const Requirement &req,
   }
   }
 
-  Rules.emplace_back(subjectTerm, constraintTerm);
+  RequirementRules.emplace_back(subjectTerm, constraintTerm);
 }
 
 void RequirementMachine::verify(const MutableTerm &term) const {
@@ -366,7 +367,8 @@ void RequirementMachine::addGenericSignature(CanGenericSignature sig) {
 
   // Add the initial set of rewrite rules to the rewrite system, also
   // providing the protocol graph to use for the linear order on terms.
-  System.initialize(std::move(builder.Rules),
+  System.initialize(std::move(builder.AssociatedTypeRules),
+                    std::move(builder.RequirementRules),
                     std::move(builder.Protocols));
 
   computeCompletion();

lib/AST/RequirementMachine/RewriteSystem.cpp

@@ -64,11 +64,18 @@ RewriteSystem::~RewriteSystem() {
 }
 
 void RewriteSystem::initialize(
-    std::vector<std::pair<MutableTerm, MutableTerm>> &&rules,
+    std::vector<std::pair<MutableTerm, MutableTerm>> &&associatedTypeRules,
+    std::vector<std::pair<MutableTerm, MutableTerm>> &&requirementRules,
     ProtocolGraph &&graph) {
   Protos = graph;
 
-  for (const auto &rule : rules)
+  for (const auto &rule : associatedTypeRules) {
+    bool added = addRule(rule.first, rule.second);
+    if (added)
+      Rules.back().markPermanent();
+  }
+
+  for (const auto &rule : requirementRules)
     addRule(rule.first, rule.second);
 }
 

lib/AST/RequirementMachine/RewriteSystem.h

@@ -105,6 +105,16 @@ class Rule final {
     Simplified = true;
   }
 
+  void markPermanent() {
+    assert(!Permanent);
+    Permanent = true;
+  }
+
+  void markRedundant() {
+    assert(!Redundant);
+    Redundant = true;
+  }
+
   /// Returns the length of the left hand side.
   unsigned getDepth() const {
     return LHS.size();
@@ -329,7 +339,8 @@ class RewriteSystem final {
   /// Return the object recording information about known protocols.
   const ProtocolGraph &getProtocols() const { return Protos; }
 
-  void initialize(std::vector<std::pair<MutableTerm, MutableTerm>> &&rules,
+  void initialize(std::vector<std::pair<MutableTerm, MutableTerm>> &&assocaitedTypeRules,
+                  std::vector<std::pair<MutableTerm, MutableTerm>> &&requirementRules,
                   ProtocolGraph &&protos);
 
   Symbol simplifySubstitutionsInSuperclassOrConcreteSymbol(Symbol symbol) const;