RequirementMachine: Make Terms work as DenseMap keys

Author: slavapestov

lib/AST/RequirementMachine/Term.h

@@ -65,6 +65,10 @@ class Term final {
     return Ptr;
   }
 
+  static Term fromOpaquePointer(void *ptr) {
+    return Term((Storage *) ptr);
+  }
+
   static Term get(const MutableTerm &term, RewriteContext &ctx);
 
   ArrayRef<const ProtocolDecl *> getRootProtocols() const {
@@ -203,4 +207,24 @@ class MutableTerm final {
 
 } // end namespace swift
 
+namespace llvm {
+  template<> struct DenseMapInfo<swift::rewriting::Term> {
+    static swift::rewriting::Term getEmptyKey() {
+      return swift::rewriting::Term::fromOpaquePointer(
+        llvm::DenseMapInfo<void *>::getEmptyKey());
+    }
+    static swift::rewriting::Term getTombstoneKey() {
+      return swift::rewriting::Term::fromOpaquePointer(
+        llvm::DenseMapInfo<void *>::getTombstoneKey());
+    }
+    static unsigned getHashValue(swift::rewriting::Term Val) {
+      return DenseMapInfo<void *>::getHashValue(Val.getOpaquePointer());
+    }
+    static bool isEqual(swift::rewriting::Term LHS,
+                        swift::rewriting::Term RHS) {
+      return LHS == RHS;
+    }
+  };
+} // end namespace llvm
+
 #endif