[RemoteMirrors] Fix losing the remote address on StaticMirror

The Offset field of a DynamicRelocation is either an offset or a remote
address, but was being treated only as a remote address on
getDynamicSymbol.

Author: augusto2112

include/swift/StaticMirror/ObjectFileContext.h

@@ -39,8 +39,12 @@ class Image {
   uint64_t HeaderAddress;
   std::vector<Segment> Segments;
   struct DynamicRelocation {
+    /// The symbol name that the pointer refers to. Empty if only an absolute
+    /// address is available.
     StringRef Symbol;
-    uint64_t Offset;
+    // The offset (if the symbol is available), or the resolved remote address
+    // if the symbol is empty.
+    uint64_t OffsetOrAddress;
   };
   llvm::DenseMap<uint64_t, DynamicRelocation> DynamicRelocations;
 

lib/StaticMirror/ObjectFileContext.cpp

@@ -332,9 +332,13 @@ remote::RemoteAbsolutePointer Image::getDynamicSymbol(uint64_t Addr) const {
   auto found = DynamicRelocations.find(Addr);
   if (found == DynamicRelocations.end())
     return nullptr;
-  return remote::RemoteAbsolutePointer(found->second.Symbol,
-                                       found->second.Offset,
-                                       remote::RemoteAddress((uint64_t)0));
+  if (!found->second.Symbol.empty())
+    return remote::RemoteAbsolutePointer(found->second.Symbol,
+                                         found->second.OffsetOrAddress,
+                                         remote::RemoteAddress());
+  return remote::RemoteAbsolutePointer(
+      remote::RemoteAddress(found->second.OffsetOrAddress,
+                            remote::RemoteAddress::DefaultAddressSpace));
 }
 
 std::pair<const Image *, uint64_t>