[ThinLTO] PrintStatistics when we exit early for thinlto-index-only

[tejohnson]

Summary

This is necessary to get stats from the ThinLink printed before the
early exit when compiling in a distributed build.

[mehdi_amini]

LGTM.

llvm/trunk/test/tools/gold/X86/stats.ll

 ; REQUIRES: asserts
 
 ; RUN: llvm-as %s -o %t.o
 ; RUN: %gold -plugin %llvmshlibdir/LLVMgold.so  -shared \
 ; RUN:    -m elf_x86_64 \
 ; RUN:    -plugin-opt=-stats %t.o -o %t2 2>&1 | FileCheck %s
 
+; RUN: llvm-as %s -o %t.o
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold.so  -shared \
+; RUN:    -m elf_x86_64 \
+; RUN:    -plugin-opt=thinlto \
+; RUN:    -plugin-opt=thinlto-index-only \
+; RUN:    -plugin-opt=-stats %t.o -o %t2 2>&1 | FileCheck %s
+
 ; CHECK: Statistics Collected
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"

llvm/trunk/tools/gold/gold-plugin.cpp

 //===-- gold-plugin.cpp - Plugin to gold for Link Time Optimization  ------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This is a gold plugin for LLVM. It provides an LLVM implementation of the
 // interface described in http://gcc.gnu.org/wiki/whopr/driver .
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/ADT/Statistic.h"
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "llvm/CodeGen/CommandFlags.h"
 #include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/LTO/Caching.h"
 #include "llvm/LTO/LTO.h"
static ld_plugin_status allSymbolsReadHook() {
 
   check(Lto->run(AddStream, Cache));
 
   if (options::TheOutputType == options::OT_DISABLE ||
       options::TheOutputType == options::OT_BC_ONLY)
     return LDPS_OK;
 
   if (options::thinlto_index_only) {
+    if (llvm::AreStatisticsEnabled())
+      llvm::PrintStatistics();
     cleanup_hook();
     exit(0);
   }
 
   for (unsigned I = 0; I != MaxTasks; ++I)
     if (!Filenames[I].empty())
       recordFile(Filenames[I].str(), IsTemporary[I]);