-ftime-report: reorganize timers

The code generation time is unclear in the -ftime-report output:

* The two clang timers "Code Generation Time" and "LLVM IR Generation
  Time" are in the default group "Miscellaneous Ungrouped Timers".
* There is also a "Clang front-end time" group, which actually includes
  code generation time.

```
===-------------------------------------------------------------------------===
                         Miscellaneous Ungrouped Timers
===-------------------------------------------------------------------------===

   ---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name ---
   0.0611 (  1.7%)   0.0099 (  4.4%)   0.0710 (  1.9%)   0.0713 (  1.9%)  LLVM IR Generation Time
   3.5140 ( 98.3%)   0.2165 ( 95.6%)   3.7306 ( 98.1%)   3.7342 ( 98.1%)  Code Generation Time
   3.5751 (100.0%)   0.2265 (100.0%)   3.8016 (100.0%)   3.8055 (100.0%)  Total
...
===-------------------------------------------------------------------------===
                          Clang front-end time report
===-------------------------------------------------------------------------===
  Total Execution Time: 3.9108 seconds (3.9146 wall clock)

   ---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name ---
   3.6802 (100.0%)   0.2306 (100.0%)   3.9108 (100.0%)   3.9146 (100.0%)  Clang front-end timer
   3.6802 (100.0%)   0.2306 (100.0%)   3.9108 (100.0%)   3.9146 (100.0%)  Total
```

This patch

* renames "Clang front-end time report" (FrontendAction time) to "Clang
  time report",
* renames "Clang front-end" to "Front end",
* moves "LLVM IR Generation" into the group,
* replaces "Code Generation time" with "Optimizer" (middle end) and
  "Machine code generation" (back end).

```
% clang -c sqlite3.i -w -ftime-report -mllvm -sort-timers=0
...
===-------------------------------------------------------------------------===
                               Clang time report
===-------------------------------------------------------------------------===
  Total Execution Time: 1.5922 seconds (1.5972 wall clock)

   ---User Time---   --System Time--   --User+System--   ---Wall Time---  --- Name ---
   0.5107 ( 35.9%)   0.0105 (  6.2%)   0.5211 ( 32.7%)   0.5222 ( 32.7%)  Front end
   0.2464 ( 17.3%)   0.0340 ( 20.0%)   0.2804 ( 17.6%)   0.2814 ( 17.6%)  LLVM IR generation
   0.6240 ( 43.9%)   0.1235 ( 72.7%)   0.7475 ( 47.0%)   0.7503 ( 47.0%)  Machine code generation
   0.0413 (  2.9%)   0.0018 (  1.0%)   0.0431 (  2.7%)   0.0433 (  2.7%)  Optimizer
   1.4224 (100.0%)   0.1698 (100.0%)   1.5922 (100.0%)   1.5972 (100.0%)  Total
```

Pull Request: https://github.com/llvm/llvm-project/pull/122225

1 files changed, 10 insertions, 14 deletions

diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index fbfc305..b00a4ac 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -722,11 +722,8 @@ void CompilerInstance::createCodeCompletionConsumer() {
 }
 
 void CompilerInstance::createFrontendTimer() {
-  FrontendTimerGroup.reset(
-      new llvm::TimerGroup("frontend", "Clang front-end time report"));
-  FrontendTimer.reset(
-      new llvm::Timer("frontend", "Clang front-end timer",
-                      *FrontendTimerGroup));
+  timerGroup.reset(new llvm::TimerGroup("clang", "Clang time report"));
+  FrontendTimer.reset(new llvm::Timer("frontend", "Front end", *timerGroup));
 }
 
 CodeCompleteConsumer *
@@ -1726,10 +1723,9 @@ void CompilerInstance::createASTReader() {
   const FrontendOptions &FEOpts = getFrontendOpts();
   std::unique_ptr<llvm::Timer> ReadTimer;
 
-  if (FrontendTimerGroup)
+  if (timerGroup)
     ReadTimer = std::make_unique<llvm::Timer>("reading_modules",
-                                                "Reading modules",
-                                                *FrontendTimerGroup);
+                                              "Reading modules", *timerGroup);
   TheASTReader = new ASTReader(
       getPreprocessor(), getModuleCache(), &getASTContext(),
       getPCHContainerReader(), getFrontendOpts().ModuleFileExtensions,
@@ -1758,10 +1754,10 @@ void CompilerInstance::createASTReader() {
 bool CompilerInstance::loadModuleFile(
     StringRef FileName, serialization::ModuleFile *&LoadedModuleFile) {
   llvm::Timer Timer;
-  if (FrontendTimerGroup)
+  if (timerGroup)
     Timer.init("preloading." + FileName.str(), "Preloading " + FileName.str(),
-               *FrontendTimerGroup);
-  llvm::TimeRegion TimeLoading(FrontendTimerGroup ? &Timer : nullptr);
+               *timerGroup);
+  llvm::TimeRegion TimeLoading(timerGroup ? &Timer : nullptr);
 
   // If we don't already have an ASTReader, create one now.
   if (!TheASTReader)
@@ -1892,10 +1888,10 @@ ModuleLoadResult CompilerInstance::findOrCompileModuleAndReadAST(
 
   // Time how long it takes to load the module.
   llvm::Timer Timer;
-  if (FrontendTimerGroup)
+  if (timerGroup)
     Timer.init("loading." + ModuleFilename, "Loading " + ModuleFilename,
-               *FrontendTimerGroup);
-  llvm::TimeRegion TimeLoading(FrontendTimerGroup ? &Timer : nullptr);
+               *timerGroup);
+  llvm::TimeRegion TimeLoading(timerGroup ? &Timer : nullptr);
   llvm::TimeTraceScope TimeScope("Module Load", ModuleName);
 
   // Try to load the module file. If we are not trying to load from the