Iterative type checker: collapse "enumerate dependencies" and "satisfy".

DougGregor · DougGregor · commit b49964e39e41 · 2015-10-09T17:18:41.000Z
The separate "enumerate dependencies" and "satisfy" phases didn't make
sense, because one often needs to process part of a request to enumerate
additional dependencies. Collapse these two phases into a single
"process" operation that makes what progress it can, and enumerates
additional dependencies that need to be satisfied before it can
progress further.

Swift SVN r32563
diff --git a/include/swift/Sema/IterativeTypeChecker.h b/include/swift/Sema/IterativeTypeChecker.h
@@ -43,15 +43,17 @@ class IterativeTypeChecker {
   // enumerateDependenciesOf<request kind> functions, and
   // satisfy<request kind> functions.
 #define TYPE_CHECK_REQUEST(Request,PayloadName)                         \
-  bool is##Request##Satisfied(                                        \
-         TypeCheckRequest::PayloadName##PayloadType payload);         \
-  void enumerateDependenciesOf##Request(                              \
-         TypeCheckRequest::PayloadName##PayloadType payload,          \
-         llvm::function_ref<void(TypeCheckRequest)> fn);              \
-  void satisfy##Request(TypeCheckRequest::PayloadName##PayloadType payload);
+  bool is##Request##Satisfied(                                          \
+         TypeCheckRequest::PayloadName##PayloadType payload);           \
+  void process##Request(                                                \
+         TypeCheckRequest::PayloadName##PayloadType payload,            \
+         llvm::function_ref<void(TypeCheckRequest)> recordDependency);
 
 #include "swift/Sema/TypeCheckRequestKinds.def"
 
+  void process(TypeCheckRequest request,
+               llvm::function_ref<void(TypeCheckRequest)> recordDependency);
+
 public:
   IterativeTypeChecker(TypeChecker &tc) : TC(tc) { }
 
diff --git a/lib/Sema/ITCDecl.cpp b/lib/Sema/ITCDecl.cpp
@@ -85,15 +85,9 @@ bool IterativeTypeChecker::isTypeCheckInheritedClauseEntrySatisfied(
   return !inherited.getType().isNull();
 }
 
-void IterativeTypeChecker::enumerateDependenciesOfTypeCheckInheritedClauseEntry(
+void IterativeTypeChecker::processTypeCheckInheritedClauseEntry(
        TypeCheckRequest::InheritedClauseEntryPayloadType payload,
-       llvm::function_ref<void(TypeCheckRequest)>) {
-  // FIXME: depends on type checking the TypeRepr for this inheritance
-  // clause entry.
-}
-
-void IterativeTypeChecker::satisfyTypeCheckInheritedClauseEntry(
-       TypeCheckRequest::InheritedClauseEntryPayloadType payload) {
+       llvm::function_ref<void(TypeCheckRequest)> recordDependency) {
   TypeResolutionOptions options;
   DeclContext *dc;
   TypeLoc *inherited;
@@ -122,36 +116,31 @@ bool IterativeTypeChecker::isTypeCheckSuperclassSatisfied(ClassDecl *payload) {
   return payload->LazySemanticInfo.Superclass.getInt();
 }
 
-void IterativeTypeChecker::enumerateDependenciesOfTypeCheckSuperclass(
-       ClassDecl *payload,
-       llvm::function_ref<void(TypeCheckRequest)> fn) {
+void IterativeTypeChecker::processTypeCheckSuperclass(
+       ClassDecl *classDecl,
+       llvm::function_ref<void(TypeCheckRequest)> recordDependency) {
   // The superclass should be the first inherited type. However, so
   // long as we see already-resolved types that refer to protocols,
   // skip over them to keep looking for a misplaced superclass. The
   // actual error will be diagnosed when we perform full semantic
   // analysis on the class itself.
-  auto inheritedClause = payload->getInherited();
+  Type superclassType;
+  auto inheritedClause = classDecl->getInherited();
   for (unsigned i = 0, n = inheritedClause.size(); i != n; ++i) {
     TypeLoc &inherited = inheritedClause[i];
 
     // If this inherited type has not been resolved, we depend on it.
     if (!inherited.getType()) {
-      fn(TypeCheckRequest(TypeCheckRequest::TypeCheckInheritedClauseEntry,
-                          { payload, i }));
+      recordDependency(
+        TypeCheckRequest(TypeCheckRequest::TypeCheckInheritedClauseEntry,
+                         { classDecl, i }));
       return;
     }
 
     // If this resolved inherited type is existential, keep going.
     if (inherited.getType()->isExistentialType()) continue;
 
-    break;
-  }
-}
-
-void IterativeTypeChecker::satisfyTypeCheckSuperclass(ClassDecl *classDecl) {
-  // Loop through the inheritance clause looking for a class type.
-  Type superclassType;
-  for (const auto &inherited : classDecl->getInherited()) {
+    // If this resolved type is a class, we're done.
     if (inherited.getType()->getClassOrBoundGenericClass()) {
       superclassType = inherited.getType();
       break;
@@ -169,42 +158,30 @@ bool IterativeTypeChecker::isTypeCheckRawTypeSatisfied(EnumDecl *payload) {
   return payload->LazySemanticInfo.RawType.getInt();
 }
 
-void IterativeTypeChecker::enumerateDependenciesOfTypeCheckRawType(
-       EnumDecl *payload,
-       llvm::function_ref<void(TypeCheckRequest)> fn) {
+void IterativeTypeChecker::processTypeCheckRawType(
+       EnumDecl *enumDecl,
+       llvm::function_ref<void(TypeCheckRequest)> recordDependency) {
   // The raw type should be the first inherited type. However, so
   // long as we see already-resolved types that refer to protocols,
   // skip over them to keep looking for a misplaced raw type. The
   // actual error will be diagnosed when we perform full semantic
   // analysis on the enum itself.
-  auto inheritedClause = payload->getInherited();
+  Type rawType;
+  auto inheritedClause = enumDecl->getInherited();
   for (unsigned i = 0, n = inheritedClause.size(); i != n; ++i) {
     TypeLoc &inherited = inheritedClause[i];
 
     // If this inherited type has not been resolved, we depend on it.
     if (!inherited.getType()) {
-      fn(TypeCheckRequest(TypeCheckRequest::TypeCheckInheritedClauseEntry,
-                          { payload, i }));
+      recordDependency(
+        TypeCheckRequest(TypeCheckRequest::TypeCheckInheritedClauseEntry,
+                         { enumDecl, i }));
       return;
     }
 
     // If this resolved inherited type is existential, keep going.
     if (inherited.getType()->isExistentialType()) continue;
 
-    break;
-  }
-}
-
-void IterativeTypeChecker::satisfyTypeCheckRawType(EnumDecl *enumDecl) {
-  // Loop through the inheritance clause looking for a non-existential
-  // nominal type.
-  Type rawType;
-  for (const auto &inherited : enumDecl->getInherited()) {
-    if (!inherited.getType()) break;
-
-    // Skip existential types.
-    if (inherited.getType()->isExistentialType()) continue;
-
     // Record this raw type.
     rawType = inherited.getType();
     break;
@@ -221,40 +198,40 @@ bool IterativeTypeChecker::isInheritedProtocolsSatisfied(ProtocolDecl *payload){
   return payload->isInheritedProtocolsValid();
 }
 
-void IterativeTypeChecker::enumerateDependenciesOfInheritedProtocols(
-       ProtocolDecl *payload,
-       llvm::function_ref<void(TypeCheckRequest)> fn) {
+void IterativeTypeChecker::processInheritedProtocols(
+       ProtocolDecl *protocol,
+       llvm::function_ref<void(TypeCheckRequest)> recordDependency) {
   // Computing the set of inherited protocols depends on the complete
   // inheritance clause.
   // FIXME: Technically, we only need very basic name binding.
-  auto inheritedClause = payload->getInherited();
+  auto inheritedClause = protocol->getInherited();
+  bool anyDependencies = false;
+  llvm::SmallSetVector<ProtocolDecl *, 4> allProtocols;
   for (unsigned i = 0, n = inheritedClause.size(); i != n; ++i) {
     TypeLoc &inherited = inheritedClause[i];
 
     // If this inherited type has not been resolved, we depend on it.
     if (!inherited.getType()) {
-      fn(TypeCheckRequest(TypeCheckRequest::TypeCheckInheritedClauseEntry,
-                          { payload, i }));
+      recordDependency(
+        TypeCheckRequest(TypeCheckRequest::TypeCheckInheritedClauseEntry,
+                         { protocol, i }));
+      anyDependencies = true;
+      continue;
     }
-  }
-}
-
-void IterativeTypeChecker::satisfyInheritedProtocols(ProtocolDecl *protocol) {
-  // Gather all of the existential types in the inherited list.
-  // Loop through the inheritance clause looking for a non-existential
-  // nominal type.
-  llvm::SmallSetVector<ProtocolDecl *, 4> allProtocols;
-  for (const auto &inherited : protocol->getInherited()) {
-    if (!inherited.getType()) continue;
 
     // Collect existential types.
     // FIXME: We'd prefer to keep what the user wrote here.
     SmallVector<ProtocolDecl *, 4> protocols;
     if (inherited.getType()->isExistentialType(protocols)) {
       allProtocols.insert(protocols.begin(), protocols.end());
+      continue;
     }
   }
 
+  // If we enumerated any dependencies, we can't complete this request.
+  if (anyDependencies)
+    return;
+
   // FIXME: Hack to deal with recursion elsewhere.
   if (protocol->isInheritedProtocolsValid())
     return;
diff --git a/lib/Sema/IterativeTypeChecker.cpp b/lib/Sema/IterativeTypeChecker.cpp
@@ -29,26 +29,25 @@ DiagnosticEngine &IterativeTypeChecker::getDiags() const {
   return getASTContext().Diags;
 }
 
-/// Determine whether the given request has already been satisfied.
-bool IterativeTypeChecker::isSatisfied(TypeCheckRequest request) {
+void IterativeTypeChecker::process(
+       TypeCheckRequest request,
+       llvm::function_ref<void(TypeCheckRequest)> recordDependency) {
   switch (request.getKind()) {
-#define TYPE_CHECK_REQUEST(Request,PayloadName)                         \
-  case TypeCheckRequest::Request:                                       \
-    return is##Request##Satisfied(request.get##PayloadName##Payload());
+#define TYPE_CHECK_REQUEST(Request,PayloadName)                   \
+  case TypeCheckRequest::Request:                                 \
+    return process##Request(request.get##PayloadName##Payload(),  \
+                            recordDependency);
 
 #include "swift/Sema/TypeCheckRequestKinds.def"
   }
 }
 
-void IterativeTypeChecker::enumerateDependenciesOf(
-       TypeCheckRequest request,
-       llvm::function_ref<void(TypeCheckRequest)> fn) {
+/// Determine whether the given request has already been satisfied.
+bool IterativeTypeChecker::isSatisfied(TypeCheckRequest request) {
   switch (request.getKind()) {
-#define TYPE_CHECK_REQUEST(Request,PayloadName)         \
-  case TypeCheckRequest::Request:                       \
-    return enumerateDependenciesOf##Request(            \
-             request.get##PayloadName##Payload(),       \
-             fn);
+#define TYPE_CHECK_REQUEST(Request,PayloadName)                         \
+  case TypeCheckRequest::Request:                                       \
+    return is##Request##Satisfied(request.get##PayloadName##Payload());
 
 #include "swift/Sema/TypeCheckRequestKinds.def"
   }
@@ -58,35 +57,25 @@ void IterativeTypeChecker::satisfy(TypeCheckRequest request) {
   // If the request has already been satisfied, we're done.
   if (isSatisfied(request)) return;
 
-  // Make sure all of the dependencies have been satisfied before continuing.
   while (true) {
-    // Enumerate all of the dependencies of this request and capture
-    // those that have not been satisfied.
+    // Process this requirement, enumerating dependencies if anything else needs
+    // to be handled first.
     SmallVector<TypeCheckRequest, 4> unsatisfied;
-    enumerateDependenciesOf(request, [&](TypeCheckRequest dependency) {
-      // If the dependency has already been satisfied, there's nothing to do.
-      if (isSatisfied(dependency)) return;
-
+    process(request, [&](TypeCheckRequest dependency) {
       // Record the unsatisfied dependency.
       unsatisfied.push_back(dependency);
     });
 
-    // If all dependencies were satisfied, we're done.
-    if (unsatisfied.empty()) break;
+    // If there were no unsatisfied dependencies, we're done.
+    if (unsatisfied.empty()) {
+      assert(isSatisfied(request));
+      break;
+    }
 
     // Recurse to satisfy any unsatisfied dependencies.
     // FIXME: Don't recurse in the iterative type checker, silly!
-    for (auto dependency: unsatisfied) {
+    for (auto dependency : unsatisfied) {
       satisfy(dependency);
     }
   }
-
-  // Satisfy this request.
-  switch (request.getKind()) {
-#define TYPE_CHECK_REQUEST(Request,PayloadName)                         \
-  case TypeCheckRequest::Request:                                       \
-    return satisfy##Request(request.get##PayloadName##Payload());
-
-#include "swift/Sema/TypeCheckRequestKinds.def"
-  }
 }
