[llvm-dwp] Initial partial prototype

This just concatenates the common DWP sections without doing any of the
fancy DWP things like:

1) update str_offsets
2) deduplicating strings
3) merging/creating cu/tu_index

Patches for these will follow shortly.

(also not sure about target triple/object file type for this tool - do I
really need a whole triple just to write an object file that contains
purely static/hardcoded bytes in each section? & I guess I should just
pick it based on the first input, maybe, rather than hardcoding for now
- but we only produce .dwo on ELF platforms with objcopy for now anyway)

llvm-svn: 254355

1 files changed, 143 insertions, 1 deletions

diff --git a/llvm/tools/llvm-dwp/llvm-dwp.cpp b/llvm/tools/llvm-dwp/llvm-dwp.cpp
index b2f997621be..7f9f6678db0 100644
--- a/llvm/tools/llvm-dwp/llvm-dwp.cpp
+++ b/llvm/tools/llvm-dwp/llvm-dwp.cpp
@@ -1,2 +1,144 @@
-int main() {
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringSet.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCObjectFileInfo.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/Options.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/TargetSelect.h"
+#include <memory>
+#include <list>
+#include <unordered_set>
+
+using namespace llvm;
+using namespace cl;
+
+OptionCategory DwpCategory("Specific Options");
+static list<std::string> InputFiles(Positional, OneOrMore,
+                                    desc("<input files>"), cat(DwpCategory));
+
+static opt<std::string> OutputFilename(Required, "o", desc("Specify the output file."),
+                                      value_desc("filename"), cat(DwpCategory));
+
+static int error(const Twine &Error, const Twine &Context) {
+  errs() << Twine("while processing ") + Context + ":\n";
+  errs() << Twine("error: ") + Error + "\n";
+  return 1;
+}
+
+static std::error_code writeSection(MCStreamer &Out, MCSection *OutSection,
+                                    const object::SectionRef &Sym) {
+  StringRef Contents;
+  if (auto Err = Sym.getContents(Contents))
+    return Err;
+  Out.SwitchSection(OutSection);
+  Out.EmitBytes(Contents);
+  return std::error_code();
+}
+
+static std::error_code write(MCStreamer &Out, ArrayRef<std::string> Inputs) {
+  for (const auto &Input : Inputs) {
+    auto ErrOrObj = object::ObjectFile::createObjectFile(Input);
+    if (!ErrOrObj)
+      return ErrOrObj.getError();
+    const auto *Obj = ErrOrObj->getBinary();
+    for (const auto &Section : Obj->sections()) {
+      const auto &MCOFI = *Out.getContext().getObjectFileInfo();
+      static const StringMap<MCSection *> KnownSections = {
+          {"debug_info.dwo", MCOFI.getDwarfInfoDWOSection()},
+          {"debug_types.dwo", MCOFI.getDwarfTypesDWOSection()},
+          {"debug_str_offsets.dwo", MCOFI.getDwarfStrOffDWOSection()},
+          {"debug_str.dwo", MCOFI.getDwarfStrDWOSection()},
+          {"debug_loc.dwo", MCOFI.getDwarfLocDWOSection()},
+          {"debug_abbrev.dwo", MCOFI.getDwarfAbbrevDWOSection()}};
+      StringRef Name;
+      if (std::error_code Err = Section.getName(Name))
+        return Err;
+      if (MCSection *OutSection =
+              KnownSections.lookup(Name.substr(Name.find_first_not_of("._"))))
+        if (auto Err = writeSection(Out, OutSection, Section))
+          return Err;
+    }
+  }
+  return std::error_code();
+}
+
+int main(int argc, char** argv) {
+
+  ParseCommandLineOptions(argc, argv, "merge split dwarf (.dwo) files");
+
+  llvm::InitializeAllTargetInfos();
+  llvm::InitializeAllTargetMCs();
+  llvm::InitializeAllTargets();
+  llvm::InitializeAllAsmPrinters();
+
+  std::string ErrorStr;
+  StringRef Context = "dwarf streamer init";
+
+  Triple TheTriple("x86_64-linux-gnu");
+
+  // Get the target.
+  const Target *TheTarget =
+      TargetRegistry::lookupTarget("", TheTriple, ErrorStr);
+  if (!TheTarget)
+    return error(ErrorStr, Context);
+  std::string TripleName = TheTriple.getTriple();
+
+  // Create all the MC Objects.
+  std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TripleName));
+  if (!MRI)
+    return error(Twine("no register info for target ") + TripleName, Context);
+
+  std::unique_ptr<MCAsmInfo> MAI(TheTarget->createMCAsmInfo(*MRI, TripleName));
+  if (!MAI)
+    return error("no asm info for target " + TripleName, Context);
+
+  MCObjectFileInfo MOFI;
+  MCContext MC(MAI.get(), MRI.get(), &MOFI);
+  MOFI.InitMCObjectFileInfo(TheTriple, Reloc::Default, CodeModel::Default,
+                             MC);
+
+  auto MAB = TheTarget->createMCAsmBackend(*MRI, TripleName, "");
+  if (!MAB)
+    return error("no asm backend for target " + TripleName, Context);
+
+  std::unique_ptr<MCInstrInfo> MII(TheTarget->createMCInstrInfo());
+  if (!MII)
+    return error("no instr info info for target " + TripleName, Context);
+
+  std::unique_ptr<MCSubtargetInfo> MSTI(
+      TheTarget->createMCSubtargetInfo(TripleName, "", ""));
+  if (!MSTI)
+    return error("no subtarget info for target " + TripleName, Context);
+
+  MCCodeEmitter *MCE = TheTarget->createMCCodeEmitter(*MII, *MRI, MC);
+  if (!MCE)
+    return error("no code emitter for target " + TripleName, Context);
+
+  // Create the output file.
+  std::error_code EC;
+  raw_fd_ostream OutFile(OutputFilename, EC, sys::fs::F_None);
+  if (EC)
+    return error(Twine(OutputFilename) + ": " + EC.message(), Context);
+
+  std::unique_ptr<MCStreamer> MS(TheTarget->createMCObjectStreamer(
+      TheTriple, MC, *MAB, OutFile, MCE, *MSTI, false,
+      /*DWARFMustBeAtTheEnd*/ false));
+  if (!MS)
+    return error("no object streamer for target " + TripleName, Context);
+
+  if (auto Err = write(*MS, InputFiles))
+    return error(Err.message(), "Writing DWP file");
+
+  MS->Finish();
 }