[stats] Add -trace-stats-events

Author: graydon

include/swift/Frontend/FrontendOptions.h

@@ -220,6 +220,9 @@ class FrontendOptions {
   /// The path to which we should output statistics files.
   std::string StatsOutputDir;
 
+  /// Trace changes to stats to files in StatsOutputDir.
+  bool TraceStats = false;
+
   /// Indicates whether function body parsing should be delayed
   /// until the end of all files.
   bool DelayedFunctionBodyParsing = false;

include/swift/Option/Options.td

@@ -194,6 +194,9 @@ def driver_time_compilation : Flag<["-"], "driver-time-compilation">,
 def stats_output_dir: Separate<["-"], "stats-output-dir">,
   Flags<[FrontendOption, HelpHidden]>,
   HelpText<"Directory to write unified compilation-statistics files to">;
+def trace_stats_events: Flag<["-"], "trace-stats-events">,
+  Flags<[FrontendOption, HelpHidden]>,
+  HelpText<"Trace changes to stats in -stats-output-dir">;
 
 def emit_dependencies : Flag<["-"], "emit-dependencies">,
   Flags<[FrontendOption, NoInteractiveOption, DoesNotAffectIncrementalBuild]>,

lib/Driver/ToolChains.cpp

@@ -151,6 +151,7 @@ static void addCommonFrontendArgs(const ToolChain &TC,
   inputArgs.AddLastArg(arguments, options::OPT_swift_version);
   inputArgs.AddLastArg(arguments, options::OPT_enforce_exclusivity_EQ);
   inputArgs.AddLastArg(arguments, options::OPT_stats_output_dir);
+  inputArgs.AddLastArg(arguments, options::OPT_trace_stats_events);
   inputArgs.AddLastArg(arguments,
                        options::OPT_solver_shrink_unsolved_threshold);
   inputArgs.AddLastArg(arguments, options::OPT_O_Group);

lib/Frontend/CompilerInvocation.cpp

@@ -194,6 +194,9 @@ static bool ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   Opts.DebugTimeCompilation |= Args.hasArg(OPT_debug_time_compilation);
   if (const Arg *A = Args.getLastArg(OPT_stats_output_dir)) {
     Opts.StatsOutputDir = A->getValue();
+    if (Args.getLastArg(OPT_trace_stats_events)) {
+      Opts.TraceStats = true;
+    }
   }
 
   if (const Arg *A = Args.getLastArg(OPT_validate_tbd_against_ir_EQ)) {

lib/FrontendTool/FrontendTool.cpp

@@ -1360,13 +1360,17 @@ int swift::performFrontend(ArrayRef<const char *> Args,
     StringRef OutFile = FEOpts.getSingleOutputFilename();
     StringRef OutputType = llvm::sys::path::extension(OutFile);
     std::string TripleName = LangOpts.Target.normalize();
+    auto &SM = Instance->getSourceMgr();
+    auto Trace = Invocation.getFrontendOptions().TraceStats;
     StatsReporter = llvm::make_unique<UnifiedStatsReporter>("swift-frontend",
                                                             FEOpts.ModuleName,
                                                             InputName,
                                                             TripleName,
                                                             OutputType,
                                                             OptType,
-                                                            StatsOutputDir);
+                                                            StatsOutputDir,
+                                                            &SM,
+                                                            Trace);
   }
 
   const DiagnosticOptions &diagOpts = Invocation.getDiagnosticOptions();