[LTO] Add stats-file option to LTO/Config.h.

This patch adds a StatsFile option to LTO/Config.h and updates both
LLVMGold and llvm-lto2 to set it.

Reviewers: MatzeB, tejohnson, espindola

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D45531

llvm-svn: 330411

include/llvm/LTO/Config.h

@@ -88,6 +88,9 @@ struct Config {
   /// Whether to emit the pass manager debuggging informations.
   bool DebugPassManager = false;
 
+  /// Statistics output file path.
+  std::string StatsFile;
+
   bool ShouldDiscardValueNames = true;
   DiagnosticHandlerFunction DiagHandler;
 

lib/LTO/LTO.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/LTO/LTO.h"
+#include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Bitcode/BitcodeReader.h"
@@ -791,9 +792,26 @@ Error LTO::run(AddStreamFn AddStream, NativeObjectCache Cache) {
   };
   computeDeadSymbols(ThinLTO.CombinedIndex, GUIDPreservedSymbols, isPrevailing);
 
-  if (auto E = runRegularLTO(AddStream))
-    return E;
-  return runThinLTO(AddStream, Cache);
+  // Setup output file to emit statistics.
+  std::unique_ptr<ToolOutputFile> StatsFile = nullptr;
+  if (!Conf.StatsFile.empty()) {
+    EnableStatistics(false);
+    std::error_code EC;
+    StatsFile =
+        llvm::make_unique<ToolOutputFile>(Conf.StatsFile, EC, sys::fs::F_None);
+    if (EC)
+      return errorCodeToError(EC);
+    StatsFile->keep();
+  }
+
+  Error Result = runRegularLTO(AddStream);
+  if (!Result)
+    Result = runThinLTO(AddStream, Cache);
+
+  if (StatsFile)
+    PrintStatisticsJSON(StatsFile->os());
+
+  return Result;
 }
 
 Error LTO::runRegularLTO(AddStreamFn AddStream) {

test/tools/gold/X86/stats-file-option.ll

@@ -0,0 +1,23 @@
+; RUN: llvm-as -o %t.bc %s
+
+; Try to save statistics to file.
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext -plugin-opt=stats-file=%t2.stats \
+; RUN:    -m elf_x86_64 -r -o %t.o %t.bc
+; RUN: FileCheck --input-file=%t2.stats %s
+
+; CHECK: {
+; CHECK: "asm-printer.EmittedInsts":
+; CHECK: }
+
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @foo() {
+  ret i32 10
+}
+
+; Try to save statistics to an invalid file.
+; RUN: not %gold -plugin %llvmshlibdir/LLVMgold%shlibext -plugin-opt=stats-file=%t2/foo.stats \
+; RUN:    -m elf_x86_64 -r -o %t.o %t.bc 2>&1 | FileCheck --check-prefix=ERROR %s
+; ERROR: LLVM gold plugin: No such file or directory

test/tools/llvm-lto2/X86/stats-file-option.ll

@@ -0,0 +1,23 @@
+; RUN: llvm-as < %s > %t1.bc
+
+; Try to save statistics to file.
+; RUN: llvm-lto2 run %t1.bc -o %t.o -r %t1.bc,patatino,px -stats-file=%t2.stats
+; RUN: FileCheck --input-file=%t2.stats %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @patatino() {
+  fence seq_cst
+  ret void
+}
+
+; CHECK: {
+; CHECK: "asm-printer.EmittedInsts":
+; CHECK: }
+
+
+; Try to save statistics to an invalid file.
+; RUN: not llvm-lto2 run %t1.bc -o %t.o -r %t1.bc,patatino,px \
+; RUN:     -stats-file=%t2/foo.stats 2>&1 | FileCheck --check-prefix=ERROR %s
+; ERROR: LTO::run failed: No such file or directory

tools/gold/gold-plugin.cpp

@@ -203,6 +203,8 @@ namespace options {
   static std::string objcopy;
   // Directory to store the .dwo files.
   static std::string dwo_dir;
+  /// Statistics output filename.
+  static std::string stats_file;
 
   // Optimization remarks filename and hotness options
   static std::string OptRemarksFilename;
@@ -278,6 +280,8 @@ namespace options {
       OptRemarksFilename = opt.substr(strlen("opt-remarks-filename="));
     } else if (opt == "opt-remarks-with-hotness") {
       OptRemarksWithHotness = true;
+    } else if (opt.startswith("stats-file=")) {
+      stats_file = opt.substr(strlen("stats-file="));
     } else {
       // Save this option to pass to the code generator.
       // ParseCommandLineOptions() expects argv[0] to be program name. Lazily
@@ -899,6 +903,7 @@ static std::unique_ptr<LTO> createLTO(IndexWriteCallback OnIndexWrite,
   // Debug new pass manager if requested
   Conf.DebugPassManager = options::debug_pass_manager;
 
+  Conf.StatsFile = options::stats_file;
   return llvm::make_unique<LTO>(std::move(Conf), Backend,
                                 options::ParallelCodeGenParallelismLevel);
 }

tools/llvm-lto2/llvm-lto2.cpp

@@ -113,6 +113,9 @@ static cl::opt<bool>
     DebugPassManager("debug-pass-manager", cl::init(false), cl::Hidden,
                      cl::desc("Print pass management debugging information"));
 
+static cl::opt<std::string>
+    StatsFile("stats-file", cl::desc("Filename to write statistics to"));
+
 static void check(Error E, std::string Msg) {
   if (!E)
     return;
@@ -240,6 +243,7 @@ static int run(int argc, char **argv) {
 
   Conf.OverrideTriple = OverrideTriple;
   Conf.DefaultTriple = DefaultTriple;
+  Conf.StatsFile = StatsFile;
 
   ThinBackend Backend;
   if (ThinLTODistributedIndexes)