[TimeProfiler] Fix "OptModule" section and add new "Backend" sections

[anton-afanasyev]

Summary

Remove unnecessary "OptModule" section. Add "PerFunctionPasses", "PerModulePasses" and "CodeGenPasses" sections under "Backend" section.

[lebedev.ri]

Oh nice!

I like this.

One more related question - there are two "Frontend" sections, second one appears to consist only of "CodeGen Function"s.
Is that correct? Should they both be in an actual front-end section, and should they be renamed to, i dunno,
"Sema" and "Codegen"? I'm not sure about this, just raising a question.

[anton-afanasyev]

In D68161#1686632, @lebedev.ri wrote:

Oh nice!

I like this.

One more related question - there are two "Frontend" sections, second one appears to consist only of "CodeGen Function"s.
Is that correct? Should they both be in an actual front-end section, and should they be renamed to, i dunno,
"Sema" and "Codegen"? I'm not sure about this, just raising a question.

Ok, committing this.

As for two "Frontend" sections -- we've discussed this several months ago (https://reviews.llvm.org/D63325#1544555), it is not obvious how to join these sections to one (start and finish of such section are separated a lot and the code for joining is opaque).

[anton-afanasyev]

Commited long time ago (https://reviews.llvm.org/rL373142).

clang/lib/CodeGen/BackendUtil.cpp

void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
   // Before executing passes, print the final values of the LLVM options.
   cl::PrintOptionValues();
 
   // Run passes. For now we do all passes at once, but eventually we
   // would like to have the option of streaming code generation.
 
   {
     PrettyStackTraceString CrashInfo("Per-function optimization");
+    llvm::TimeTraceScope TimeScope("PerFunctionPasses", StringRef(""));
 
     PerFunctionPasses.doInitialization();
     for (Function &F : *TheModule)
       if (!F.isDeclaration())
         PerFunctionPasses.run(F);
     PerFunctionPasses.doFinalization();
   }
 
   {
     PrettyStackTraceString CrashInfo("Per-module optimization passes");
+    llvm::TimeTraceScope TimeScope("PerModulePasses", StringRef(""));
     PerModulePasses.run(*TheModule);
   }
 
   {
     PrettyStackTraceString CrashInfo("Code generation");
+    llvm::TimeTraceScope TimeScope("CodeGenPasses", StringRef(""));
     CodeGenPasses.run(*TheModule);
   }
 
   if (ThinLinkOS)
     ThinLinkOS->keep();
   if (DwoOS)
     DwoOS->keep();
 }

llvm/lib/IR/LegacyPassManager.cpp

bool FPPassManager::runOnFunction(Function &F) {
   }
 
   return Changed;
 }
 
 bool FPPassManager::runOnModule(Module &M) {
   bool Changed = false;
 
-  llvm::TimeTraceScope TimeScope("OptModule", M.getName());
   for (Function &F : M)
     Changed |= runOnFunction(F);
 
   return Changed;
 }
 
 bool FPPassManager::doInitialization(Module &M) {
   bool Changed = false;