[RemoteMirror] Add support for QueryDataLayoutFunction to the interop header.

Remote Mirror added a new callback, QueryDataLayoutFunction, which provides a nicer and more extensible way to provide things like the target pointer size. Add support for that in the interop header. Search for and call the new creation function when it exists, and shim in support for older libraries that don't have it.

rdar://problem/52849572

Author: mikeash

include/swift/SwiftRemoteMirror/SwiftRemoteMirrorLegacyInterop.h

@@ -44,6 +44,15 @@ swift_reflection_interop_createReflectionContext(
     GetStringLengthFunction GetStringLength,
     GetSymbolAddressFunction GetSymbolAddress);
 
+static inline SwiftReflectionInteropContextRef
+swift_reflection_interop_createReflectionContextWithDataLayout(
+    void *ReaderContext,
+    QueryDataLayoutFunction DataLayout,
+    FreeBytesFunction FreeBytes,
+    ReadBytesFunction ReadBytes,
+    GetStringLengthFunction GetStringLength,
+    GetSymbolAddressFunction GetSymbolAddress);
+
 /// Add a library handle to the interop context. Returns 1 if the
 /// library was added successfully, 0 if a symbol couldn't be looked up
 /// or the reported metadata version is too old.
@@ -193,6 +202,15 @@ struct SwiftReflectionFunctions {
     ReadBytesFunction ReadBytes,
     GetStringLengthFunction GetStringLength,
     GetSymbolAddressFunction GetSymbolAddress);
+
+  // Optional creation function that takes a data layout query function.
+  SwiftReflectionContextRef (*createReflectionContextWithDataLayout)(
+    void *ReaderContext,
+    QueryDataLayoutFunction DataLayout,
+    FreeBytesFunction FreeBytes,
+    ReadBytesFunction ReadBytes,
+    GetStringLengthFunction GetStringLength,
+    GetSymbolAddressFunction GetSymbolAddress);
 
   SwiftReflectionContextRef (*createReflectionContextLegacy)(
     void *ReaderContext,
@@ -298,7 +316,7 @@ struct SwiftReflectionInteropContextLegacyImageRangeList {
 
 struct SwiftReflectionInteropContext {
   void *ReaderContext;
-  uint8_t PointerSize;
+  QueryDataLayoutFunction DataLayout;
   FreeBytesFunction FreeBytes;
   ReadBytesFunction ReadBytes;
   uint64_t (*GetStringLength)(void *reader_context,
@@ -409,11 +427,12 @@ swift_reflection_interop_loadFunctions(struct SwiftReflectionInteropContext *Con
 #ifndef __cplusplus
 #define decltype(x) void *
 #endif
-#define LOAD_NAMED(field, symbol) do { \
+#define LOAD_NAMED(field, symbol, required) do { \
     Functions->field = (decltype(Functions->field))dlsym(Handle, symbol); \
-    if (Functions->field == NULL) return 0; \
+    if (required && Functions->field == NULL) return 0; \
   } while (0)
-#define LOAD(name) LOAD_NAMED(name, "swift_reflection_" #name)
+#define LOAD(name) LOAD_NAMED(name, "swift_reflection_" #name, 1)
+#define LOAD_OPT(name) LOAD_NAMED(name, "swift_reflection_" #name, 0)
 
   Functions->classIsSwiftMaskPtr =
     (unsigned long long *)dlsym(Handle, "swift_reflection_classIsSwiftMask");
@@ -425,15 +444,18 @@ swift_reflection_interop_loadFunctions(struct SwiftReflectionInteropContext *Con
   int IsLegacy = dlsym(Handle, "swift_reflection_addImage") == NULL;
 
   if (IsLegacy) {
-    LOAD_NAMED(createReflectionContextLegacy, "swift_reflection_createReflectionContext");
-    LOAD_NAMED(addReflectionInfoLegacy, "swift_reflection_addReflectionInfo");
+    LOAD_NAMED(createReflectionContextLegacy, "swift_reflection_createReflectionContext", 1);
+    LOAD_NAMED(addReflectionInfoLegacy, "swift_reflection_addReflectionInfo", 1);
   } else {
     LOAD(createReflectionContext);
     LOAD(addReflectionInfo);
     LOAD(addImage);
     LOAD(ownsObject);
     LOAD(ownsAddress);
     LOAD(metadataForObject);
+    
+    // Optional creation function.
+    LOAD_OPT(createReflectionContextWithDataLayout);
   }
 
   LOAD(destroyReflectionContext);
@@ -508,6 +530,32 @@ swift_reflection_interop_GetSymbolAddressAdapter(
   return Context->GetSymbolAddress(Context->ReaderContext, name, name_length);
 }
 
+static inline int
+swift_reflection_interop_minimalDataLayoutQueryFunction4(
+  void *ReaderContext,
+  DataLayoutQueryType type,
+  void *inBuffer, void *outBuffer) {
+  if (type == DLQ_GetPointerSize || type == DLQ_GetSizeSize) {
+    uint8_t *result = (uint8_t *)outBuffer;
+    *result = 4;
+    return 1;
+  }
+  return 0;
+}
+
+static inline int
+swift_reflection_interop_minimalDataLayoutQueryFunction8(
+  void *ReaderContext,
+  DataLayoutQueryType type,
+  void *inBuffer, void *outBuffer) {
+  if (type == DLQ_GetPointerSize || type == DLQ_GetSizeSize) {
+    uint8_t *result = (uint8_t *)outBuffer;
+    *result = 8;
+    return 1;
+  }
+  return 0;
+}
+
 static inline SwiftReflectionInteropContextRef
 swift_reflection_interop_createReflectionContext(
     void *ReaderContext,
@@ -516,12 +564,37 @@ swift_reflection_interop_createReflectionContext(
     ReadBytesFunction ReadBytes,
     GetStringLengthFunction GetStringLength,
     GetSymbolAddressFunction GetSymbolAddress) {
-  
+  QueryDataLayoutFunction DataLayout;
+  if (PointerSize == 4)
+    DataLayout = swift_reflection_interop_minimalDataLayoutQueryFunction4;
+  else if (PointerSize == 8)
+    DataLayout = swift_reflection_interop_minimalDataLayoutQueryFunction8;
+  else
+    abort(); // Can't handle sizes other than 4 and 8.
+
+  return swift_reflection_interop_createReflectionContextWithDataLayout(
+    ReaderContext,
+    NULL,
+    FreeBytes,
+    ReadBytes,
+    GetStringLength,
+    GetSymbolAddress);
+}
+
+static inline SwiftReflectionInteropContextRef
+swift_reflection_interop_createReflectionContextWithDataLayout(
+    void *ReaderContext,
+    QueryDataLayoutFunction DataLayout,
+    FreeBytesFunction FreeBytes,
+    ReadBytesFunction ReadBytes,
+    GetStringLengthFunction GetStringLength,
+    GetSymbolAddressFunction GetSymbolAddress) { 
+ 
   SwiftReflectionInteropContextRef ContextRef =
     (SwiftReflectionInteropContextRef)calloc(sizeof(*ContextRef), 1);
 
   ContextRef->ReaderContext = ReaderContext;
-  ContextRef->PointerSize = PointerSize;
+  ContextRef->DataLayout = DataLayout;
   ContextRef->FreeBytes = FreeBytes;
   ContextRef->ReadBytes = ReadBytes;
   ContextRef->GetStringLength = GetStringLength;
@@ -548,10 +621,29 @@ swift_reflection_interop_addLibrary(
         swift_reflection_interop_readBytesAdapter,
         swift_reflection_interop_GetStringLengthAdapter,
         swift_reflection_interop_GetSymbolAddressAdapter);
+    } else if (Library->Functions.createReflectionContextWithDataLayout) {
+      Library->Context =
+        Library->Functions.createReflectionContextWithDataLayout(
+        ContextRef->ReaderContext,
+        ContextRef->DataLayout,
+        ContextRef->FreeBytes,
+        ContextRef->ReadBytes,
+        ContextRef->GetStringLength,
+        ContextRef->GetSymbolAddress);          
     } else {
+      uint8_t PointerSize;
+      int result = ContextRef->DataLayout(
+        ContextRef->ReaderContext, DLQ_GetPointerSize, NULL, &PointerSize);
+      if (!result)
+        abort(); // We need the pointer size, can't proceed without it.
+
       Library->Context = Library->Functions.createReflectionContext(
         ContextRef->ReaderContext,
-      ContextRef->PointerSize, ContextRef->FreeBytes, ContextRef->ReadBytes, ContextRef->GetStringLength, ContextRef->GetSymbolAddress);
+        PointerSize,
+        ContextRef->FreeBytes,
+        ContextRef->ReadBytes,
+        ContextRef->GetStringLength,
+        ContextRef->GetSymbolAddress);
     }
   }
   return Success;