Expose GetAddressingBits() in the Process API

[aprantl]

Summary

See https://github.com/apple/llvm-project/pull/4110 for motivation and context.

[JDevlieghere]

LGTM

[kastiglione]

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

216

Thought: should this API return a mask instead?

[aprantl]

This turned out to be unnecessary, because Process already exposes this.

lldb/include/lldb/Target/Process.h

 
 protected:
   virtual JITLoaderList &GetJITLoaders();
 
 public:
   /// Get the system architecture for this process.
   virtual ArchSpec GetSystemArchitecture() { return {}; }
 
+  /// Return the number of bits in a vmaddr that are used by valid addresses.
+  virtual llvm::Optional<uint32_t> GetAddressingBits() { return {}; }
+
   /// Get the system runtime plug-in for this process.
   ///
   /// \return
   ///   Returns a pointer to the SystemRuntime plugin for this Process
   ///   if one is available.  Else returns nullptr.
   virtual SystemRuntime *GetSystemRuntime();
 
   /// Attach to an existing process using the process attach info.

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h

public:
   static llvm::StringRef GetPluginNameStatic() { return "gdb-remote"; }
 
   static llvm::StringRef GetPluginDescriptionStatic();
 
   static std::chrono::seconds GetPacketTimeout();
 
   ArchSpec GetSystemArchitecture() override;
 
+  llvm::Optional<uint32_t> GetAddressingBits() override;
+
   // Check if a given Process
   bool CanDebug(lldb::TargetSP target_sp,
                 bool plugin_specified_by_name) override;
 
   CommandObject *GetPluginCommandObject() override;
 
   // Creating a new process, or attaching to an existing one
   Status WillLaunch(Module *module) override;

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

 std::chrono::seconds ProcessGDBRemote::GetPacketTimeout() {
   return std::chrono::seconds(GetGlobalPluginProperties().GetPacketTimeout());
 }
 
 ArchSpec ProcessGDBRemote::GetSystemArchitecture() {
   return m_gdb_comm.GetHostArchitecture();
 }
 
+llvm::Optional<uint32_t> ProcessGDBRemote::GetAddressingBits() {
+  return m_gdb_comm.GetAddressingBits();
+}
+
 bool ProcessGDBRemote::CanDebug(lldb::TargetSP target_sp,
                                 bool plugin_specified_by_name) {
   if (plugin_specified_by_name)
     return true;
 
   // For now we are just making sure the file exists for a given module
   Module *exe_module = target_sp->GetExecutableModulePointer();
   if (exe_module) {