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

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 change 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.

Reviewed by: mehdi_amini

Differential Revision: https://reviews.llvm.org/D32803

llvm-svn: 303152

include/llvm/IR/LegacyPassManager.h

@@ -98,6 +98,9 @@ private:
 // Create wrappers for C Binding types (see CBindingWrapping.h).
 DEFINE_STDCXX_CONVERSION_FUNCTIONS(legacy::PassManagerBase, LLVMPassManagerRef)
 
+/// If -time-passes has been specified, report the timings immediately and then
+/// reset the timers to zero.
+void reportAndResetTimings();
 } // End llvm namespace
 
 #endif

lib/IR/LegacyPassManager.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #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"
@@ -465,6 +466,11 @@ public:
   // 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())
@@ -1752,6 +1758,13 @@ Timer *llvm::getPassTimer(Pass *P) {
   return nullptr;
 }
 
+/// If timing is enabled, report the times collected up to now and then reset
+/// them.
+void llvm::reportAndResetTimings() {
+  if (TheTimeInfo)
+    TheTimeInfo->print();
+}
+
 //===----------------------------------------------------------------------===//
 // PMStack implementation
 //

lib/LTO/LTOCodeGenerator.cpp

@@ -597,6 +597,7 @@ bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
   // If statistics were requested, print them out after codegen.
   if (llvm::AreStatisticsEnabled())
     llvm::PrintStatistics();
+  reportAndResetTimings();
 
   finishOptimizationRemarks();
 

lib/LTO/ThinLTOCodeGenerator.cpp

@@ -1024,4 +1024,5 @@ void ThinLTOCodeGenerator::run() {
   // If statistics were requested, print them out now.
   if (llvm::AreStatisticsEnabled())
     llvm::PrintStatistics();
+  reportAndResetTimings();
 }