[clang][timers][stats] Add a flag to enable timers in the stats file (llvm#149946)

As reported in llvm#138173, enabling `-ftime-report` adds pass timing info
to the stats file if `-stats-file` is specified. This was determined to
be WAI. However, if one intentionally wants to put timer information in
the stats file, using `-ftime-report` may lead to a lot of logspam (that
can't be removed by directing stderr to `/dev/null` as that would also
redirect compiler errors). To address this, this PR adds a flag
`-stats-file-timers` that adds timer data to the stats file without
outputting to stderr.

Author: alanzhao1

clang/include/clang/Basic/CodeGenOptions.def

@@ -313,9 +313,10 @@ CODEGENOPT(SpeculativeLoadHardening, 1, 0, Benign) ///< Enable speculative load
 CODEGENOPT(FineGrainedBitfieldAccesses, 1, 0, Benign) ///< Enable fine-grained bitfield accesses.
 CODEGENOPT(StrictEnums       , 1, 0, Benign) ///< Optimize based on strict enum definition.
 CODEGENOPT(StrictVTablePointers, 1, 0, Benign) ///< Optimize based on the strict vtable pointers
-CODEGENOPT(TimePasses        , 1, 0, Benign) ///< Set when -ftime-report or -ftime-report= or -ftime-report-json is enabled.
+CODEGENOPT(TimePasses        , 1, 0, Benign) ///< Set when -ftime-report, -ftime-report=, -ftime-report-json, or -stats-file-timers is enabled.
 CODEGENOPT(TimePassesPerRun  , 1, 0, Benign) ///< Set when -ftime-report=per-pass-run is enabled.
 CODEGENOPT(TimePassesJson    , 1, 0, Benign) ///< Set when -ftime-report-json is enabled.
+CODEGENOPT(TimePassesStatsFile     , 1, 0, Benign) ///< Set when -stats-file-timers is enabled.
 CODEGENOPT(TimeTrace         , 1, 0, Benign) ///< Set when -ftime-trace is enabled.
 VALUE_CODEGENOPT(TimeTraceGranularity, 32, 500, Benign) ///< Minimum time granularity (in microseconds),
                                                         ///< traced by time profiler

clang/include/clang/Driver/Options.td

@@ -8261,6 +8261,9 @@ def stats_file : Joined<["-"], "stats-file=">,
 def stats_file_append : Flag<["-"], "stats-file-append">,
   HelpText<"If stats should be appended to stats-file instead of overwriting it">,
   MarshallingInfoFlag<FrontendOpts<"AppendStats">>;
+def stats_file_timers : Flag<["-"], "stats-file-timers">,
+                        HelpText<"If stats should include timers.">,
+                        MarshallingInfoFlag<CodeGenOpts<"TimePassesStatsFile">>;
 def fdump_record_layouts_simple : Flag<["-"], "fdump-record-layouts-simple">,
   HelpText<"Dump record layout information in a simple form used for testing">,
   MarshallingInfoFlag<LangOpts<"DumpRecordLayoutsSimple">>;

clang/lib/Frontend/CompilerInvocation.cpp

@@ -2013,8 +2013,8 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
             : llvm::codegenoptions::DebugTemplateNamesKind::Mangled);
   }
 
-  if (const Arg *A = Args.getLastArg(OPT_ftime_report, OPT_ftime_report_EQ,
-                                     OPT_ftime_report_json)) {
+  if (Args.hasArg(OPT_ftime_report, OPT_ftime_report_EQ, OPT_ftime_report_json,
+                  OPT_stats_file_timers)) {
     Opts.TimePasses = true;
 
     // -ftime-report= is only for new pass manager.
@@ -2026,7 +2026,7 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
         Opts.TimePassesPerRun = true;
       else
         Diags.Report(diag::err_drv_invalid_value)
-            << A->getAsString(Args) << A->getValue();
+            << EQ->getAsString(Args) << EQ->getValue();
     }
 
     if (Args.getLastArg(OPT_ftime_report_json))

clang/test/Misc/time-passes.c

@@ -19,6 +19,12 @@
 // RUN:     -ftime-report-json %s -o /dev/null \
 // RUN:     -mllvm -info-output-file=%t
 // RUN: cat %t | FileCheck %s --check-prefixes=JSON
+// Check that -stats-file-timers only outputs pass time info in the stats file
+// and not stderr.
+// RUN: %clang_cc1 -emit-obj -O1 \
+// RUN:     %s -o /dev/null \
+// RUN:     -stats-file=%t -stats-file-timers 2>&1 | count 0
+// RUN: FileCheck %s -input-file=%t -check-prefixes=JSON
 
 // TIME: Pass execution timing report
 // TIME: Total Execution Time:

clang/tools/driver/cc1_main.cpp

@@ -304,7 +304,7 @@ int cc1_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
     *IOFile << "{\n";
     llvm::TimerGroup::printAllJSONValues(*IOFile, "");
     *IOFile << "\n}\n";
-  } else {
+  } else if (!Clang->getCodeGenOpts().TimePassesStatsFile) {
     llvm::TimerGroup::printAll(*IOFile);
   }
   llvm::TimerGroup::clearAll();