[lldb] Move resolvePointer code to resolvePointerAsSymbol

resolvePointerAsSymbol is executed before any memory read is done, so
move the code that does this to it.

Author: augusto2112

lldb/source/Plugins/LanguageRuntime/Swift/LLDBMemoryReader.cpp

@@ -119,25 +119,22 @@ LLDBMemoryReader::getSymbolAddress(const std::string &name) {
   return swift::remote::RemoteAddress(load_addr);
 }
 
-swift::remote::RemoteAbsolutePointer
-LLDBMemoryReader::resolvePointer(swift::remote::RemoteAddress address,
-                                 uint64_t readValue) {
+llvm::Optional<swift::remote::RemoteAbsolutePointer>
+LLDBMemoryReader::resolvePointerAsSymbol(swift::remote::RemoteAddress address) {
   // If an address has a symbol, that symbol provides additional useful data to
   // MetadataReader. Without the symbol, MetadataReader can derive the symbol
   // by loading other parts of reflection metadata, but that work has a cost.
   // For lldb, that data loading can be a significant performance hit. Providing
   // a symbol greatly reduces memory read traffic to the process.
-  auto pointer = swift::remote::RemoteAbsolutePointer("", readValue);
-
   auto &target = m_process.GetTarget();
   if (!target.GetSwiftUseReflectionSymbols())
-    return pointer;
+    return {};
 
   llvm::Optional<Address> maybeAddr =
       resolveRemoteAddress(address.getAddressData());
   // This is not an assert, but should never happen.
   if (!maybeAddr)
-    return pointer;
+    return {};
 
   Address addr;
   if (maybeAddr->IsSectionOffset()) {
@@ -146,21 +143,21 @@ LLDBMemoryReader::resolvePointer(swift::remote::RemoteAddress address,
   } else {
     // `address` is a real load address.
     if (!target.ResolveLoadAddress(address.getAddressData(), addr))
-      return pointer;
+      return {};
   }
 
   if (!addr.GetSection()->CanContainSwiftReflectionData())
-    return pointer;
+    return {};
 
   if (auto *symbol = addr.CalculateSymbolContextSymbol()) {
     auto mangledName = symbol->GetMangled().GetMangledName().GetStringRef();
     // MemoryReader requires this to be a Swift symbol. LLDB can also be
     // aware of local symbols, so avoid returning those.
     if (swift::Demangle::isSwiftSymbol(mangledName))
-      return {mangledName, 0};
+      return {{mangledName, 0}};
   }
 
-  return pointer;
+  return {};
 }
 
 bool LLDBMemoryReader::readBytes(swift::remote::RemoteAddress address,

lldb/source/Plugins/LanguageRuntime/Swift/LLDBMemoryReader.h

@@ -23,9 +23,8 @@ class LLDBMemoryReader : public swift::remote::MemoryReader {
   swift::remote::RemoteAddress
   getSymbolAddress(const std::string &name) override;
 
-  swift::remote::RemoteAbsolutePointer
-  resolvePointer(swift::remote::RemoteAddress address,
-                 uint64_t readValue) override;
+  llvm::Optional<swift::remote::RemoteAbsolutePointer>
+  resolvePointerAsSymbol(swift::remote::RemoteAddress address) override;
 
   bool readBytes(swift::remote::RemoteAddress address, uint8_t *dest,
                  uint64_t size) override;