[trace][intel pt] Support dumping the trace info in json

Thanks to ymeng@fb.com for coming up with this change.

`thread trace dump info` can dump some metrics that can be useful for
analyzing the performance and quality of a trace. This diff adds a --json
option for dumping this information in json format that can be easily
understood my machines.

Differential Revision: https://reviews.llvm.org/D129332

1 files changed, 7 insertions, 8 deletions

diff --git a/lldb/source/Commands/CommandObjectThread.cpp b/lldb/source/Commands/CommandObjectThread.cpp
index 1b92702..ad49d27 100644
--- a/lldb/source/Commands/CommandObjectThread.cpp
+++ b/lldb/source/Commands/CommandObjectThread.cpp
@@ -2351,6 +2351,10 @@ public:
         m_verbose = true;
         break;
       }
+      case 'j': {
+        m_json = true;
+        break;
+      }
       default:
         llvm_unreachable("Unimplemented option");
       }
@@ -2359,6 +2363,7 @@ public:
 
     void OptionParsingStarting(ExecutionContext *execution_context) override {
       m_verbose = false;
+      m_json = false;
     }
 
     llvm::ArrayRef<OptionDefinition> GetDefinitions() override {
@@ -2367,15 +2372,9 @@ public:
 
     // Instance variables to hold the values for command options.
     bool m_verbose;
+    bool m_json;
   };
 
-  bool DoExecute(Args &command, CommandReturnObject &result) override {
-    Target &target = m_exe_ctx.GetTargetRef();
-    result.GetOutputStream().Format("Trace technology: {0}\n",
-                                    target.GetTrace()->GetPluginName());
-    return CommandObjectIterateOverThreads::DoExecute(command, result);
-  }
-
   CommandObjectTraceDumpInfo(CommandInterpreter &interpreter)
       : CommandObjectIterateOverThreads(
             interpreter, "thread trace dump info",
@@ -2397,7 +2396,7 @@ protected:
     ThreadSP thread_sp =
         m_exe_ctx.GetProcessPtr()->GetThreadList().FindThreadByID(tid);
     trace_sp->DumpTraceInfo(*thread_sp, result.GetOutputStream(),
-                            m_options.m_verbose);
+                            m_options.m_verbose, m_options.m_json);
     return true;
   }