Emit symbol maps for compiled code for use by the Linux perf tool.

runtime/bin/main.cc

Index: runtime/bin/main.cc
diff --git a/runtime/bin/main.cc b/runtime/bin/main.cc
index 7bcd30caa3dee129929b76f5f5abc1237af7a8d9..c96ee87bf51a60ac0fdd359b64887d2b6a43d317 100644
--- a/runtime/bin/main.cc
+++ b/runtime/bin/main.cc
@@ -35,6 +35,11 @@ static const char* original_working_directory = NULL;
 static CommandLineOptions* import_map_options = NULL;
 
 
+// Global state that indicates whether perf_events symbol information
+// is to be generated or not.
+static File* perf_events_symbols_file = NULL;
+
+
 // Global state that indicates whether pprof symbol information is
 // to be generated or not.
 static const char* generate_pprof_symbols_filename = NULL;
@@ -128,6 +133,23 @@ static void ProcessDebugOption(const char* port) {
 }
 
 
+static void ProcessPerfEventsOption(const char* option) {
+  ASSERT(option != NULL);
+  if (perf_events_symbols_file == NULL) {
+#if defined(TARGET_OS_LINUX)
+    const char* format = "/tmp/perf-%ld.map";
+    intptr_t pid = Process::CurrentProcessId();
+    intptr_t len = snprintf(NULL, 0, format, pid);
+    char* filename = new char[len + 1];
+    snprintf(filename, len + 1, format, pid);
+    perf_events_symbols_file = File::Open(filename, File::kWriteTruncate);
+    ASSERT(perf_events_symbols_file != NULL);
+    delete[] filename;
+#endif

[siva, 2012/07/25 22:25:23]

Could you abstract this away into os.h as OpenPerfSymbolsFile or something like
that instead of a #if defined(..) over here.

Also you wouldn't need the CurrentProcessId function if this is abstracted out.

[cshapiro, 2012/07/25 22:52:54]

I do not feel good about that as Linux is the only platform that would ever
provide a functioning definition.  And, because of the File::Open call, that
definition cannot appear in VM-specific code.  Having a prototype in os.h and an
implementation somewhere under bin seems awkward, I doubt that is what you
intended in this comment.

As an aside, there are profilers, such as Intel's VTune and some Valgrind tools,
which run on more than one of our targets.  Putting definitions for these
targets in the global namespace seems justifiable.

[siva, 2012/07/25 23:19:52]

Sorry I meant platform.h which is in the 'bin' directory and not os.h

I would think it is ok to have empty unreachable methods on macos and win for
it.

On 2012/07/25 22:52:54, cshapiro wrote:

[cshapiro, 2012/07/26 00:14:19]

Per our off-line conversation, I will add a TODO reminding us to find a better
place for this code.

+  }
+}
+
+
 static void ProcessPprofOption(const char* filename) {
   ASSERT(filename != NULL);
   generate_pprof_symbols_filename = filename;
@@ -154,6 +176,7 @@ static struct {
   { "--break_at=", ProcessBreakpointOption },
   { "--compile_all", ProcessCompileAllOption },
   { "--debug", ProcessDebugOption },
+  { "--generate_perf_events_symbols", ProcessPerfEventsOption },
   { "--generate_pprof_symbols=", ProcessPprofOption },
   { "--import_map=", ProcessImportMapOption },
   { "--package-root=", ProcessPackageRootOption },
@@ -178,6 +201,12 @@ static bool ProcessMainOptions(const char* option) {
 }
 
 
+static void WriteToPerfEventsFile(const char* buffer, int64_t num_bytes) {
+  ASSERT(perf_events_symbols_file != NULL);
+  perf_events_symbols_file->WriteFully(buffer, num_bytes);
+}
+
+
 static void WriteToFlowGraphFile(const char* buffer, int64_t num_bytes) {
   ASSERT(flow_graph_file != NULL);
   flow_graph_file->WriteFully(buffer, num_bytes);
@@ -217,6 +246,11 @@ static int ParseArguments(int argc,
       i++;
     }
   }
+
+  if (perf_events_symbols_file != NULL) {
+    Dart_InitPerfEventsSupport(&WriteToPerfEventsFile);
+  }
+
   if (generate_pprof_symbols_filename != NULL) {
     Dart_InitPprofSupport();
   }