[trace][intel-pt] Scaffold the 'thread trace start | stop' commands

Depends on D90490.

The stop command is simple and invokes the new method Trace::StopTracingThread(thread).

On the other hand, the start command works by delegating its implementation to a CommandObject provided by the Trace plugin. This is necessary because each trace plugin needs different options for this command. There's even the chance that a Trace plugin can't support live tracing, but instead supports offline decoding and analysis, which means that "thread trace dump instructions" works but "thread trace start" doest. Because of this and a few other reasons, it's better to have each plugin provide this implementation.

Besides, I'm using the GetSupportedTraceType method introduced in D90490 to quickly infer what's the trace plug-in that works for the current process.

As an implementation note, I moved CommandObjectIterateOverThreads to its header so that I can use it from the IntelPT plugin. Besides, the actual start and stop logic for intel-pt is not part of this diff.

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D90729

1 files changed, 30 insertions, 11 deletions

diff --git a/lldb/source/Commands/CommandObjectMultiword.cpp b/lldb/source/Commands/CommandObjectMultiword.cpp
index 9033cfe..0f20a1d 100644
--- a/lldb/source/Commands/CommandObjectMultiword.cpp
+++ b/lldb/source/Commands/CommandObjectMultiword.cpp
@@ -261,11 +261,32 @@ CommandObjectProxy::CommandObjectProxy(CommandInterpreter &interpreter,
 
 CommandObjectProxy::~CommandObjectProxy() = default;
 
+Options *CommandObjectProxy::GetOptions() {
+  CommandObject *proxy_command = GetProxyCommandObject();
+  if (proxy_command)
+    return proxy_command->GetOptions();
+  return CommandObject::GetOptions();
+}
+
+llvm::StringRef CommandObjectProxy::GetHelp() {
+  CommandObject *proxy_command = GetProxyCommandObject();
+  if (proxy_command)
+    return proxy_command->GetHelp();
+  return CommandObject::GetHelp();
+}
+
+llvm::StringRef CommandObjectProxy::GetSyntax() {
+  CommandObject *proxy_command = GetProxyCommandObject();
+  if (proxy_command)
+    return proxy_command->GetSyntax();
+  return CommandObject::GetSyntax();
+}
+
 llvm::StringRef CommandObjectProxy::GetHelpLong() {
   CommandObject *proxy_command = GetProxyCommandObject();
   if (proxy_command)
     return proxy_command->GetHelpLong();
-  return llvm::StringRef();
+  return CommandObject::GetHelpLong();
 }
 
 bool CommandObjectProxy::IsRemovable() const {
@@ -293,7 +314,9 @@ CommandObjectMultiword *CommandObjectProxy::GetAsMultiwordCommand() {
 void CommandObjectProxy::GenerateHelpText(Stream &result) {
   CommandObject *proxy_command = GetProxyCommandObject();
   if (proxy_command)
-    return proxy_command->GenerateHelpText(result);
+    proxy_command->GenerateHelpText(result);
+  else
+    CommandObject::GenerateHelpText(result);
 }
 
 lldb::CommandObjectSP
@@ -345,13 +368,6 @@ bool CommandObjectProxy::WantsCompletion() {
   return false;
 }
 
-Options *CommandObjectProxy::GetOptions() {
-  CommandObject *proxy_command = GetProxyCommandObject();
-  if (proxy_command)
-    return proxy_command->GetOptions();
-  return nullptr;
-}
-
 void CommandObjectProxy::HandleCompletion(CompletionRequest &request) {
   CommandObject *proxy_command = GetProxyCommandObject();
   if (proxy_command)
@@ -373,12 +389,15 @@ const char *CommandObjectProxy::GetRepeatCommand(Args &current_command_args,
   return nullptr;
 }
 
+llvm::StringRef CommandObjectProxy::GetUnsupportedError() {
+  return "command is not implemented";
+}
+
 bool CommandObjectProxy::Execute(const char *args_string,
                                  CommandReturnObject &result) {
   CommandObject *proxy_command = GetProxyCommandObject();
   if (proxy_command)
     return proxy_command->Execute(args_string, result);
-  result.AppendError("command is not implemented");
-  result.SetStatus(eReturnStatusFailed);
+  result.SetError(GetUnsupportedError());
   return false;
 }