Merge pull request #27418 from jckarter/reflection-symbolic-absolute-pointer

MetadataReader: Add an API for reading absolute pointers.

Author: jckarter

include/swift/Basic/ExternalUnion.h

@@ -433,27 +433,27 @@ struct MembersHelper<> {
 
   LLVM_ATTRIBUTE_ALWAYS_INLINE
   static void copyConstruct(void *self, int index, const void *other) {
-    llvm_unreachable("bad index");
+    assert(false && "bad index");
   }
 
   LLVM_ATTRIBUTE_ALWAYS_INLINE
   static void moveConstruct(void *self, int index, void *other) {
-    llvm_unreachable("bad index");
+    assert(false && "bad index");
   }
 
   LLVM_ATTRIBUTE_ALWAYS_INLINE
   static void copyAssignSame(int index, void *self, const void *other) {
-    llvm_unreachable("bad index");
+    assert(false && "bad index");
   }
 
   LLVM_ATTRIBUTE_ALWAYS_INLINE
   static void moveAssignSame(int index, void *self, void *other) {
-    llvm_unreachable("bad index");
+    assert(false && "bad index");
   }
 
   LLVM_ATTRIBUTE_ALWAYS_INLINE
   static void destruct(int index, void *self) {
-    llvm_unreachable("bad index");
+    assert(false && "bad index");
   }
 };
 

include/swift/Reflection/ReflectionContext.h

@@ -608,14 +608,17 @@ class ReflectionContext
       auto CDAddr = this->readCaptureDescriptorFromMetadata(*MetadataAddress);
       if (!CDAddr)
         return nullptr;
+      if (!CDAddr->isResolved())
+        return nullptr;
 
       // FIXME: Non-generic SIL boxes also use the HeapLocalVariable metadata
       // kind, but with a null capture descriptor right now (see
       // FixedBoxTypeInfoBase::allocate).
       //
       // Non-generic SIL boxes share metadata among types with compatible
       // layout, but we need some way to get an outgoing pointer map for them.
-      auto CD = getBuilder().getCaptureDescriptor(*CDAddr);
+      auto CD = getBuilder().getCaptureDescriptor(
+                                CDAddr->getResolvedAddress().getAddressData());
       if (CD == nullptr)
         return nullptr;
 

include/swift/Remote/MemoryReader.h

@@ -69,7 +69,7 @@ class MemoryReader {
   /// NOTE: subclasses MUST override at least one of the readBytes functions. The default
   /// implementation calls through to the other one.
   virtual ReadBytesResult
-    readBytes(RemoteAddress address, uint64_t size) {
+  readBytes(RemoteAddress address, uint64_t size) {
     auto *Buf = malloc(size);
     ReadBytesResult Result(Buf, [](const void *ptr) {
       free(const_cast<void *>(ptr));
@@ -96,6 +96,34 @@ class MemoryReader {
     memcpy(dest, Ptr.get(), size);
     return true;
   }
+  
+  /// Attempts to resolve a pointer value read from the given remote address.
+  virtual RemoteAbsolutePointer resolvePointer(RemoteAddress address,
+                                               uint64_t readValue) {
+    // Default implementation returns the read value as is.
+    return RemoteAbsolutePointer("", readValue);
+  }
+  
+  /// Attempt to read and resolve a pointer value at the given remote address.
+  llvm::Optional<RemoteAbsolutePointer> readPointer(RemoteAddress address,
+                                                    unsigned pointerSize) {
+    auto result = readBytes(address, pointerSize);
+    if (!result)
+      return llvm::None;
+    
+    uint64_t pointerData;
+    if (pointerSize == 4) {
+      uint32_t theData;
+      memcpy(&theData, result.get(), 4);
+      pointerData = theData;
+    } else if (pointerSize == 8) {
+      memcpy(&pointerData, result.get(), 8);
+    } else {
+      return llvm::None;
+    }
+    
+    return resolvePointer(address, pointerData);
+  }
 
   virtual ~MemoryReader() = default;
 };