[Support][Test] Time profiler: add regression test

[anton-afanasyev]

Summary

Add output to llvm::errs() when -ftime-trace option is enabled,
add regression test checking this option works as expected.

[aganea]

Could you please move the test to a more approriate location? (ie. clang/trunk/test/Driver/)

clang/tools/driver/cc1_main.cpp

245

This seems a bit too chatty. Suround these two lines with if (Config->Verbose) ?

llvm/test/Support/check-time-trace.cxx

4

I don't see any other -ftime-trace tests, I would add a few more exhaustive file format checks here.

[anton-afanasyev]

In D61914#1512021, @aganea wrote:

Could you please move the test to a more approriate location? (ie. clang/trunk/test/Driver/)

Thanks, I've moved it there.

clang/tools/driver/cc1_main.cpp

245

I don't think it should be done this way for several reasons:

1. This info is actually needed by user when one uses --ftime-trace since json-file is usually dumped to random filename located in /tmp/. Therefore --ftime-trace means --ftime-trace --verbose itself. Without this info user cannot understand where dumped file is. How can he know about --verbose?
2. Option --ftime-report is much more chatty, it dumps several tables to terminal. This option just dumps to file, but tells where file is.
3. I have not found elegant way to check --verbose option here, one should add it to clang::FrontendOptions or so.

llvm/test/Support/check-time-trace.cxx

4

Ok, I've added more checks, parsing json file by python.

[anton-afanasyev]

Updated

[aganea]

Thanks Anton!

[plotfi]

cfe/trunk/test/Driver/check-time-trace.cpp appears to fail on Darwin. Did you mean to pass the target explicitly ?

[plotfi]

cfe/trunk/test/Driver/check-time-trace.cpp

1 ↗

(On Diff #203544)

This test should probably have // REQUIRES: shell

[anton-afanasyev]

In D61914#1534508, @plotfi wrote:

cfe/trunk/test/Driver/check-time-trace.cpp appears to fail on Darwin. Did you mean to pass the target explicitly ?

This commit is reverted now. How can I pass the target explicitly?

cfe/trunk/test/Driver/check-time-trace.cpp

1 ↗

(On Diff #203544)

Thanks! I haven't found REQUIRES: shell here: https://llvm.org/docs/CommandGuide/FileCheck.html. Does this directive mean the target OS must have utils like awk and xargs?

clang/tools/driver/cc1_main.cpp

auto profilerOutput =
         Clang->createOutputFile(Path.str(),
                                 /*Binary=*/false,
                                 /*RemoveFileOnSignal=*/false, "",
                                 /*Extension=*/"json",
                                 /*useTemporary=*/false);
 
     llvm::timeTraceProfilerWrite(*profilerOutput);
     llvm::timeTraceProfilerCleanup();
+
+    llvm::errs() << "Time trace json-file dumped to " << Path.str() << "\n";
+    llvm::errs()
+        << "Use chrome://tracing or Speedscope App "
+           "(https://www.speedscope.app) for flamegraph visualization\n";
   }
 
   // Our error handler depends on the Diagnostics object, which we're
   // potentially about to delete. Uninstall the handler now so that any
   // later errors use the default handling behavior instead.
   llvm::remove_fatal_error_handler();
 
   // When running with -disable-free, don't do any destruction or shutdown.
   if (Clang->getFrontendOpts().DisableFree) {
     llvm::BuryPointer(std::move(Clang));
     return !Success;
   }
 
   return !Success;
 }

llvm/test/Support/check-time-trace.cxx

+// RUN: clang++ -ftime-trace %s 2>&1 | grep "Time trace json-file dumped to" \
+// RUN:   | awk '{print $NF}' | xargs cat | FileCheck %s
+
+// CHECK: "args":{"name":"clang"}
+
+#include <iostream>
+
+int main() {
+  std::cout << "Foo" << std::endl;
+  return 0;
+}