Reflection: Looking up CaptureDescriptors by remote address

Remote metadata for closure contexts points to a capture descriptor.
We have a local copy of all capture descriptors. Translate the
address by recording the local and remote start address of
reflection metadata.

Author: slavapestov

include/swift/Reflection/TypeRefBuilder.h

@@ -79,14 +79,17 @@ struct ReflectionInfo {
   CaptureSection capture;
   GenericSection typeref;
   GenericSection reflstr;
+  uintptr_t LocalStartAddress;
+  uintptr_t RemoteStartAddress;
 };
 
 struct ClosureContextInfo {
   std::vector<const TypeRef *> CaptureTypes;
   std::vector<std::pair<const TypeRef *, const MetadataSource *>> MetadataSources;
   unsigned NumBindings = 0;
 
-  void dump(std::ostream &OS);
+  void dump() const;
+  void dump(std::ostream &OS) const;
 };
 
 /// An implementation of MetadataReader's BuilderType concept for
@@ -289,6 +292,10 @@ class TypeRefBuilder {
   /// Get the primitive type lowering for a builtin type.
   const BuiltinTypeDescriptor *getBuiltinTypeInfo(const TypeRef *TR);
 
+  /// Get the raw capture descriptor for a remote capture descriptor
+  /// address.
+  const CaptureDescriptor *getCaptureDescriptor(uintptr_t RemoteAddress);
+
   /// Get the unsubstituted capture types for a closure context.
   ClosureContextInfo getClosureContextInfo(const CaptureDescriptor &CD);
 

include/swift/SwiftRemoteMirror/SwiftRemoteMirrorTypes.h

@@ -41,6 +41,10 @@ typedef struct swift_reflection_info {
   swift_reflection_section_t capture;
   swift_reflection_section_t typeref;
   swift_reflection_section_t reflstr;
+
+  // Start address in local and remote address spaces.
+  uintptr_t LocalStartAddress;
+  uintptr_t RemoteStartAddress;
 } swift_reflection_info_t;
 
 /// The layout kind of a Swift type.

stdlib/public/Reflection/TypeRefBuilder.cpp

@@ -152,6 +152,21 @@ TypeRefBuilder::getBuiltinTypeInfo(const TypeRef *TR) {
   return nullptr;
 }
 
+const CaptureDescriptor *
+TypeRefBuilder::getCaptureDescriptor(uintptr_t RemoteAddress) {
+  for (auto Info : ReflectionInfos) {
+    for (auto &CD : Info.capture) {
+      auto OtherAddr = ((uintptr_t) &CD -
+                        Info.LocalStartAddress +
+                        Info.RemoteStartAddress);
+      if (OtherAddr == RemoteAddress)
+        return &CD;
+    }
+  }
+
+  return nullptr;
+}
+
 /// Get the unsubstituted capture types for a closure context.
 ClosureContextInfo
 TypeRefBuilder::getClosureContextInfo(const CaptureDescriptor &CD) {
@@ -265,7 +280,11 @@ void TypeRefBuilder::dumpBuiltinTypeSection(std::ostream &OS) {
   }
 }
 
-void ClosureContextInfo::dump(std::ostream &OS) {
+void ClosureContextInfo::dump() const {
+  dump(std::cerr);
+}
+
+void ClosureContextInfo::dump(std::ostream &OS) const {
   OS << "- Capture types:\n";
   for (auto *TR : CaptureTypes) {
     if (TR == nullptr)

tools/swift-reflection-dump/swift-reflection-dump.cpp

@@ -127,6 +127,8 @@ static ReflectionInfo findReflectionInfo(const ObjectFile *objectFile) {
     captureSection,
     typeRefSection,
     reflectionStringsSection,
+    /*LocalStartAddress*/ 0,
+    /*RemoteStartAddress*/ 0,
   };
 }
 

tools/swift-reflection-test/swift-reflection-test.c

@@ -293,7 +293,9 @@ PipeMemoryReader_receiveReflectionInfo(SwiftReflectionContextRef RC,
       makeLocalSection(Buffer, RemoteInfo.builtin, RemoteInfo),
       makeLocalSection(Buffer, RemoteInfo.capture, RemoteInfo),
       makeLocalSection(Buffer, RemoteInfo.typeref, RemoteInfo),
-      makeLocalSection(Buffer, RemoteInfo.reflstr, RemoteInfo)
+      makeLocalSection(Buffer, RemoteInfo.reflstr, RemoteInfo),
+      /*LocalStartAddress*/ (uintptr_t) Buffer,
+      /*RemoteStartAddress*/ RemoteInfo.StartAddress,
     };
     swift_reflection_addReflectionInfo(RC, Info);
   }