Fix fetching the architecture of the target on process launch

Previously it was fetched only if the architecture isn't valid, but the
architecture can be valid without containing all information about the
current target (e.g. missing os).

Differential revision: http://reviews.llvm.org/D8057

llvm-svn: 232153

lldb/include/lldb/Target/Target.h

@@ -1071,6 +1071,9 @@ class Target :
     bool
     SetArchitecture (const ArchSpec &arch_spec);
 
+    bool
+    MergeArchitecture (const ArchSpec &arch_spec);
+
     Debugger &
     GetDebugger ()
     {

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

@@ -939,16 +939,17 @@ ProcessGDBRemote::DoLaunch (Module *exe_module, ProcessLaunchInfo &launch_info)
 
             if (m_gdb_comm.SendPacketAndWaitForResponse("?", 1, m_last_stop_packet, false) == GDBRemoteCommunication::PacketResult::Success)
             {
-                if (!m_target.GetArchitecture().IsValid()) 
+                const ArchSpec &process_arch = m_gdb_comm.GetProcessArchitecture();
+
+                if (process_arch.IsValid())
                 {
-                    if (m_gdb_comm.GetProcessArchitecture().IsValid())
-                    {
-                        m_target.SetArchitecture(m_gdb_comm.GetProcessArchitecture());
-                    }
-                    else
-                    {
-                        m_target.SetArchitecture(m_gdb_comm.GetHostArchitecture());
-                    }
+                    m_target.MergeArchitecture(process_arch);
+                }
+                else
+                {
+                    const ArchSpec &host_arch = m_gdb_comm.GetHostArchitecture();
+                    if (host_arch.IsValid())
+                        m_target.MergeArchitecture(host_arch);
                 }
 
                 SetPrivateState (SetThreadStopInfo (m_last_stop_packet));

lldb/source/Target/Target.cpp

@@ -1189,6 +1189,30 @@ Target::SetArchitecture (const ArchSpec &arch_spec)
     return false;
 }
 
+bool
+Target::MergeArchitecture (const ArchSpec &arch_spec)
+{
+    if (arch_spec.IsValid())
+    {
+        if (m_arch.IsCompatibleMatch(arch_spec))
+        {
+            // The current target arch is compatible with "arch_spec", see if we
+            // can improve our current architecture using bits from "arch_spec"
+
+            // Merge bits from arch_spec into "merged_arch" and set our architecture
+            ArchSpec merged_arch (m_arch);
+            merged_arch.MergeFrom (arch_spec);
+            return SetArchitecture(merged_arch);
+        }
+        else
+        {
+            // The new architecture is different, we just need to replace it
+            return SetArchitecture(arch_spec);
+        }
+    }
+    return false;
+}
+
 void
 Target::WillClearList (const ModuleList& module_list)
 {