LTO: Replace split dwarf implementation that uses objcopy with one that uses direct emission.

[pcc]

Summary

Part of PR37466.

Depends on D47089

[echristo]

Woo :)

-eric

llvm/include/llvm/LTO/Config.h

struct Config {
   std::string DefaultTriple;
 
   /// Sample PGO profile path.
   std::string SampleProfile;
 
   /// The directory to store .dwo files.
   std::string DwoDir;
 
-  /// The objcopy binary used to extract dwo files.
-  std::string Objcopy;
-
   /// Optimization remarks file path.
   std::string RemarksFilename = "";
 
   /// Whether to emit optimization remarks with hotness informations.
   bool RemarksWithHotness = false;
 
   /// Whether to emit the pass manager debuggging informations.
   bool DebugPassManager = false;

llvm/lib/LTO/LTOBackend.cpp

runNewPMCustomPasses(Mod, TM, Conf.OptPipeline, Conf.AAPipeline,
                          Conf.DisableVerify);
   else if (Conf.UseNewPM)
     runNewPMPasses(Conf, Mod, TM, Conf.OptLevel, IsThinLTO);
   else
     runOldPMPasses(Conf, Mod, TM, IsThinLTO, ExportSummary, ImportSummary);
   return !Conf.PostOptModuleHook || Conf.PostOptModuleHook(Task, Mod);
 }
 
-void codegenWithSplitDwarf(Config &Conf, TargetMachine *TM,
-                           AddStreamFn AddStream, unsigned Task, Module &Mod) {
-  SmallString<128> TempFile;
-  int FD = -1;
-  if (auto EC =
-      sys::fs::createTemporaryFile("lto-llvm-fission", "o", FD, TempFile))
-    report_fatal_error("Could not create temporary file " +
-        TempFile.str() + ": " + EC.message());
-  llvm::raw_fd_ostream OS(FD, true);
-  SmallString<1024> DwarfFile(Conf.DwoDir);
-  std::string DwoName = sys::path::filename(Mod.getModuleIdentifier()).str() +
-      "-" + std::to_string(Task) + "-";
-  size_t index = TempFile.str().rfind("lto-llvm-fission");
-  StringRef TempID = TempFile.str().substr(index + 17, 6);
-  DwoName += TempID.str() + ".dwo";
-  sys::path::append(DwarfFile, DwoName);
-  TM->Options.MCOptions.SplitDwarfFile = DwarfFile.str().str();
-
-  legacy::PassManager CodeGenPasses;
-  if (TM->addPassesToEmitFile(CodeGenPasses, OS, nullptr, Conf.CGFileType))
-    report_fatal_error("Failed to setup codegen");
-  CodeGenPasses.run(Mod);
-
-  if (auto EC = llvm::sys::fs::create_directories(Conf.DwoDir))
-    report_fatal_error("Failed to create directory " +
-           Conf.DwoDir + ": " + EC.message());
-
-  SmallVector<const char*, 5> ExtractArgs, StripArgs;
-  ExtractArgs.push_back(Conf.Objcopy.c_str());
-  ExtractArgs.push_back("--extract-dwo");
-  ExtractArgs.push_back(TempFile.c_str());
-  ExtractArgs.push_back(TM->Options.MCOptions.SplitDwarfFile.c_str());
-  ExtractArgs.push_back(nullptr);
-  StripArgs.push_back(Conf.Objcopy.c_str());
-  StripArgs.push_back("--strip-dwo");
-  StripArgs.push_back(TempFile.c_str());
-  StripArgs.push_back(nullptr);
-
-  if (auto Ret = sys::ExecuteAndWait(Conf.Objcopy, ExtractArgs.data())) {
-    report_fatal_error("Failed to extract dwo from " + TempFile.str() +
-        ". Exit code " + std::to_string(Ret));
-  }
-  if (auto Ret = sys::ExecuteAndWait(Conf.Objcopy, StripArgs.data())) {
-    report_fatal_error("Failed to strip dwo from " + TempFile.str() +
-        ". Exit code " + std::to_string(Ret));
-  }
-
-  auto Stream = AddStream(Task);
-  auto Buffer = MemoryBuffer::getFile(TempFile);
-  if (auto EC = Buffer.getError())
-    report_fatal_error("Failed to load file " +
-                       TempFile.str() + ": " + EC.message());
-  *Stream->OS << Buffer.get()->getBuffer();
-  if (auto EC = sys::fs::remove(TempFile))
-    report_fatal_error("Failed to delete file " +
-                       TempFile.str() + ": " + EC.message());
-}
-
 void codegen(Config &Conf, TargetMachine *TM, AddStreamFn AddStream,
              unsigned Task, Module &Mod) {
   if (Conf.PreCodeGenModuleHook && !Conf.PreCodeGenModuleHook(Task, Mod))
     return;
 
+  std::unique_ptr<ToolOutputFile> DwoOut;
   if (!Conf.DwoDir.empty()) {
-    codegenWithSplitDwarf(Conf, TM, AddStream, Task, Mod);
-    return;
+    std::error_code EC;
+    if (auto EC = llvm::sys::fs::create_directories(Conf.DwoDir))
+      report_fatal_error("Failed to create directory " + Conf.DwoDir + ": " +
+                         EC.message());
+
+    SmallString<1024> DwoFile(Conf.DwoDir);
+    sys::path::append(DwoFile, std::to_string(Task) + ".dwo");
+    TM->Options.MCOptions.SplitDwarfFile = DwoFile.str().str();
+    DwoOut = make_unique<ToolOutputFile>(DwoFile, EC, sys::fs::F_None);
+    if (EC)
+      report_fatal_error("Failed to open " + DwoFile + ": " + EC.message());
   }
 
   auto Stream = AddStream(Task);
   legacy::PassManager CodeGenPasses;
-  if (TM->addPassesToEmitFile(CodeGenPasses, *Stream->OS, nullptr,
+  if (TM->addPassesToEmitFile(CodeGenPasses, *Stream->OS,
+                              DwoOut ? &DwoOut->os() : nullptr,
                               Conf.CGFileType))
     report_fatal_error("Failed to setup codegen");
   CodeGenPasses.run(Mod);
+
+  if (DwoOut)
+    DwoOut->keep();
 }
 
 void splitCodeGen(Config &C, TargetMachine *TM, AddStreamFn AddStream,
                   unsigned ParallelCodeGenParallelismLevel,
                   std::unique_ptr<Module> Mod) {
   ThreadPool CodegenThreadPool(ParallelCodeGenParallelismLevel);
   unsigned ThreadCount = 0;
   const Target *T = &TM->getTarget();

llvm/test/tools/gold/X86/split-dwarf.ll

 ; RUN: rm -rf %t && mkdir -p %t
 ; RUN: opt -module-summary %s -o %t/split-dwarf.o
 ; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext  \
 ; RUN:    -m elf_x86_64 \
 ; RUN:    --plugin-opt=thinlto \
-; RUN:    --plugin-opt=objcopy=%llvm-objcopy \
 ; RUN:    --plugin-opt=dwo_dir=%t/dwo_dir \
 ; RUN:    %t/split-dwarf.o --shared -o %t/split-dwarf
 
 ; RUN: llvm-dwarfdump -debug-info %t/split-dwarf | FileCheck %s
-; CHECK: DW_AT_GNU_dwo_name{{.*}}dwo_dir/split-dwarf.{{.*}}
+; CHECK: DW_AT_GNU_dwo_name{{.*}}dwo_dir/1.dwo
 ; CHECK-NOT: DW_TAG_subprogram
-; RUN: llvm-dwarfdump -debug-info %t/dwo_dir/split-dwarf.* | FileCheck --check-prefix DWOCHECK %s
-; DWOCHECK: DW_AT_GNU_dwo_name{{.*}}dwo_dir/split-dwarf.o{{.*}}
+; RUN: llvm-dwarfdump -debug-info %t/dwo_dir/1.dwo | FileCheck --check-prefix DWOCHECK %s
+; DWOCHECK: DW_AT_GNU_dwo_name{{.*}}dwo_dir/1.dwo
 ; DWOCHECK: DW_AT_name{{.*}}split-dwarf.c
 ; DWOCHECK: DW_TAG_subprogram
 
 ; RUN:rm -rf %t/dwo_dir
 ; RUN: opt  %s -o %t/split-dwarf.o
 ; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext  \
 ; RUN:    -m elf_x86_64 \
 ; RUN:    --plugin-opt=thinlto \
-; RUN:    --plugin-opt=objcopy=%llvm-objcopy \
 ; RUN:    --plugin-opt=dwo_dir=%t/dwo_dir \
 ; RUN:    %t/split-dwarf.o --shared -o %t/split-dwarf
 
 ; RUN: llvm-dwarfdump -debug-info %t/split-dwarf | FileCheck --check-prefix LTOCHECK %s
-; LTOCHECK: DW_AT_GNU_dwo_name{{.*}}dwo_dir/ld-temp.{{.*}}
+; LTOCHECK: DW_AT_GNU_dwo_name{{.*}}dwo_dir/0.dwo
 ; LTOCHECK-NOT: DW_TAG_subprogram
-; RUN: llvm-dwarfdump -debug-info %t/dwo_dir/ld-temp.* | FileCheck --check-prefix LTODWOCHECK %s
-; LTODWOCHECK: DW_AT_GNU_dwo_name{{.*}}dwo_dir/ld-temp.o{{.*}}
+; RUN: llvm-dwarfdump -debug-info %t/dwo_dir/0.dwo | FileCheck --check-prefix LTODWOCHECK %s
+; LTODWOCHECK: DW_AT_GNU_dwo_name{{.*}}dwo_dir/0.dwo
 ; LTODWOCHECK: DW_AT_name{{.*}}split-dwarf.c
 ; LTODWOCHECK: DW_TAG_subprogram
 
 ; ModuleID = 'split-dwarf.c'
 source_filename = "split-dwarf.c"
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 

llvm/tools/gold/gold-plugin.cpp

#endif
   // as plugin exclusive to pass to the code generator.
   static std::vector<const char *> extra;
   // Sample profile file path
   static std::string sample_profile;
   // New pass manager
   static bool new_pass_manager = false;
   // Debug new pass manager
   static bool debug_pass_manager = false;
-  // Objcopy for debug fission.
-  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;
   static bool OptRemarksWithHotness = false;
static void process_plugin_option(const char *opt_)
     } else if (opt == "disable-verify") {
       DisableVerify = true;
     } else if (opt.startswith("sample-profile=")) {
       sample_profile= opt.substr(strlen("sample-profile="));
     } else if (opt == "new-pass-manager") {
       new_pass_manager = true;
     } else if (opt == "debug-pass-manager") {
       debug_pass_manager = true;
-    } else if (opt.startswith("objcopy=")) {
-      objcopy = opt.substr(strlen("objcopy="));
     } else if (opt.startswith("dwo_dir=")) {
       dwo_dir = opt.substr(strlen("dwo_dir="));
     } else if (opt.startswith("opt-remarks-filename=")) {
       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="));
case options::OT_SAVE_TEMPS:
     break;
   }
 
   if (!options::sample_profile.empty())
     Conf.SampleProfile = options::sample_profile;
 
   Conf.DwoDir = options::dwo_dir;
 
-  Conf.Objcopy = options::objcopy;
-
   // Set up optimization remarks handling.
   Conf.RemarksFilename = options::OptRemarksFilename;
   Conf.RemarksWithHotness = options::OptRemarksWithHotness;
 
   // Use new pass manager if set in driver
   Conf.UseNewPM = options::new_pass_manager;
   // Debug new pass manager if requested
   Conf.DebugPassManager = options::debug_pass_manager;