[RemoteMirror] Allow clients to specify whether Obj-C interop is enabled.

rdar://119570103

Author: bentroller

include/swift/Remote/InProcessMemoryReader.h

@@ -88,6 +88,8 @@ class InProcessMemoryReader final : public MemoryReader {
       }
       return true;
     }
+    case DLQ_GetObjCInteropIsEnabled:
+      break;
     }
     return false;
   }

include/swift/Remote/MemoryReader.h

@@ -195,7 +195,7 @@ class MemoryReader {
     return resolvePointer(address, pointerData);
   }
 
- // Parse extra inhabitants stored in a pointer.
+  // Parse extra inhabitants stored in a pointer.
   // Sets *extraInhabitant to -1 if the pointer at this address
   // is actually a valid pointer.
   // Otherwise, it sets *extraInhabitant to the inhabitant

include/swift/Remote/MetadataReader.h

@@ -647,8 +647,11 @@ class MetadataReader {
 
       auto classMeta = cast<TargetClassMetadata>(meta);
       while (stripSignedPointer(classMeta->Superclass)) {
-        classMeta = cast<TargetClassMetadata>(
-            readMetadata(stripSignedPointer(classMeta->Superclass)));
+        meta = readMetadata(stripSignedPointer(classMeta->Superclass));
+        if (!meta || meta->getKind() != MetadataKind::Class)
+          return llvm::None;
+
+        classMeta = cast<TargetClassMetadata>(meta);
 
         // Subtract the size contribution of the isa and retain counts from
         // the super class.

include/swift/SwiftRemoteMirror/MemoryReaderInterface.h

@@ -103,6 +103,10 @@ typedef enum {
   /// process.  This is currently 0x1000 (4096) except on 64-bit Apple platforms
   /// where it is 0x100000000.
   DLQ_GetLeastValidPointerValue,
+
+  /// The query should ignore inBuffer, and treat outBuffer as bool* which
+  /// should be populated with whether the target runtime uses Obj-C interop.
+  DLQ_GetObjCInteropIsEnabled,
 } DataLayoutQueryType;
 
 /// Data layout query function, which returns answers based on query types (from

lib/StaticMirror/ObjectFileContext.cpp

@@ -431,6 +431,8 @@ bool ObjectMemoryReader::queryDataLayout(DataLayoutQueryType type,
     }
     return true;
   }
+  case DLQ_GetObjCInteropIsEnabled:
+    break;
   }
 
   return false;