[LTO] Print time-passes information at conclusion of LTO codegen

[jhenderson]

Summary

The information collected when requested by -time-passes is only printed when llvm_shutdown is called at the moment. This means that when linking against the LTO library dynamically and using the C interface, it is not possible to see the timing information, because llvm_shutdown cannot be called. This changes modifies the LTO code generation functions for both regular LTO and thin LTO to explicitly print and reset the timing information.

I have tested that this works with our proprietary linker. However, as this relies on a specific method of building and linking against the LTO library, I'm not sure how or if this can be tested in the LLVM testsuite. Any suggestions would be appreciated.

[jhenderson]

Minor improvement to reportTimings to get rid of unnecessary check.

[jhenderson]

Ping!

[mehdi_amini]

include/llvm/IR/LegacyPassManager.h

101

Doxygen

Also the name does not carry the fact that timers are reset.

lib/IR/LegacyPassManager.cpp

15

Why this?

[jhenderson]

Renamed function and added doxygen comment.

[jhenderson]

lib/IR/LegacyPassManager.cpp

15

The new print() method of the TimingInfo class calls CreateInfoOutputFile to get a stream to print to, which is declared in that header.

[mehdi_amini]

LGTM, thanks.

include/llvm/IR/LegacyPassManager.h

private:
   Module *M;
 };
 
 } // End legacy namespace
 
 // Create wrappers for C Binding types (see CBindingWrapping.h).
 DEFINE_STDCXX_CONVERSION_FUNCTIONS(legacy::PassManagerBase, LLVMPassManagerRef)
 
+void reportTimings();
 } // End llvm namespace
 
 #endif

lib/IR/LegacyPassManager.cpp

 //===- LegacyPassManager.cpp - LLVM Pass Infrastructure Implementation ----===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the legacy LLVM Pass Manager infrastructure.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/IR/LegacyPassManager.h"
+#include "llvm/ADT/Statistic.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/LegacyPassManagers.h"
 #include "llvm/IR/LegacyPassNameParser.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
~TimingInfo() {
     // TimerGroup is deleted next, printing the report.
   }
 
   // createTheTimeInfo - This method either initializes the TheTimeInfo pointer
   // to a non-null value (if the -time-passes option is enabled) or it leaves it
   // null.  It may be called multiple times.
   static void createTheTimeInfo();
 
+  // print - Prints out timing information and then resets the timers.
+  void print() {
+      TG.print(*CreateInfoOutputFile());
+  }
+
   /// getPassTimer - Return the timer for the specified pass if it exists.
   Timer *getPassTimer(Pass *P) {
     if (P->getAsPMDataManager())
       return nullptr;
 
     sys::SmartScopedLock<true> Lock(*TimingInfoMutex);
     Timer *&T = TimingData[P];
     if (!T) {

 
 /// If TimingInfo is enabled then start pass timer.
 Timer *llvm::getPassTimer(Pass *P) {
   if (TheTimeInfo)
     return TheTimeInfo->getPassTimer(P);
   return nullptr;
 }
 
+/// If timing is enabled, report the times collected up to now and then reset
+/// them.
+void llvm::reportTimings() {
+  if (!TimePassesIsEnabled || TheTimeInfo == nullptr)
+    return;
+
+  TheTimeInfo->print();
+}
+
 //===----------------------------------------------------------------------===//
 // PMStack implementation
 //
 
 // Pop Pass Manager from the stack and clear its analysis info.
 void PMStack::pop() {
 
   PMDataManager *Top = this->top();

lib/LTO/LTOCodeGenerator.cpp

bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
   // MergedModule.
   MergedModule = splitCodeGen(std::move(MergedModule), Out, {},
                               [&]() { return createTargetMachine(); }, FileType,
                               ShouldRestoreGlobalsLinkage);
 
   // If statistics were requested, print them out after codegen.
   if (llvm::AreStatisticsEnabled())
     llvm::PrintStatistics();
+  reportTimings();
 
   finishOptimizationRemarks();
 
   return true;
 }
 
 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
 /// LTO problems.

lib/LTO/ThinLTOCodeGenerator.cpp

// Parallel optimizer + codegen
     }
   }
 
   pruneCache(CacheOptions.Path, CacheOptions.Policy);
 
   // If statistics were requested, print them out now.
   if (llvm::AreStatisticsEnabled())
     llvm::PrintStatistics();
+  reportTimings();
 }