[llvm-objdump] Add --file-headers (-f) option

[jhenderson]

tools/llvm-objdump/llvm-objdump.cpp

2135

Nit: Is there a need for the trailing whitespace in the output?

[paulsemel]

Fixing trailing white space.

[jhenderson]

I was going to ask for a documentation update, but it turns out that there is no documentation for llvm-objdump outside the help text...!

It looks to me like GNU objdump also prints some flags when -f is used. Is this something you plan to add later?

lib/Object/COFFObjectFile.cpp

916

It looks like GNU objdump prints 0 rather than failing in this case.

test/tools/llvm-objdump/file-headers.test

1 ↗

(On Diff #153732)

I must admit that I'm surprised we're not using yaml2obj to test here. I am not familiar with llvm-objdump, and I see that using pre-canned binaries is normal for its tests, but how do you feel about using yaml2obj instead?

Assuming you'd prefer to use pre-canned binaries, is it normal in the tests to use files that aren't specifically for that test?

There should also probably be separate elf and coff test cases.

tools/llvm-objdump/llvm-objdump.cpp

2312

Assuming this is what clang-format does, I suppose that this is right, but it definitely does make it a lot harder to follow :-(

[paulsemel]

About the other informations: I think they are more "format specific" and thus I wanted to add an other patch for it. Do you want me to do it in this patch ?

lib/Object/COFFObjectFile.cpp

916

Yes, I figured it out this night.. I really don't know why. Do you think we might follow the behavior ?

test/tools/llvm-objdump/file-headers.test

1 ↗

(On Diff #153732)

Yes, I anyway definitely need to add a COFF test. I can use yaml2obj here, this is not a problem for me, but as a lot of tests in this tool are doing this way, I just didn't want to break the move :)

tools/llvm-objdump/llvm-objdump.cpp

2135

Absolutely not, fixing it !

2312

Woops, shouldn't have pushed this... will go back on this modification no worries :)

[jhenderson]

In D48810#1150661, @paulsemel wrote:

About the other informations: I think they are more "format specific" and thus I wanted to add an other patch for it. Do you want me to do it in this patch ?

No, I don't think it's that important, and I'm happy for that to be added later, when someone wants to add it.

lib/Object/COFFObjectFile.cpp

916

I think it makes sense to. The other information in the file-headers dump is potentially useful, so preventing it being printed is bad (though if there's a clean way of not printing the address at all for COFF object files, I'm all for it not being printed in this case).

test/tools/llvm-objdump/file-headers.test

1 ↗

(On Diff #153732)

I think when we can do better, there's no reason to stick to the same pattern. Somebody needs to break the mould at some point!

[paulsemel]

Applied Jame's suggestions

[jhenderson]

Looks fine to me, apart from a couple of test-related comments.

test/tools/llvm-objdump/file-headers-coff.test

13

Does yaml2obj have support for PE-COFF too? If so, could you add a third test case, with a non-zero start address, please.

test/tools/llvm-objdump/file-headers-elf.test

13

Could you provide a non-zero start address, please, to show that the address is correctly read.

[paulsemel]

Added Jame's suggestions

[paulsemel]

This comment has been deleted.

test/tools/llvm-objdump/file-headers-coff.test

13

Well, as you will see, I've done what I could about it.. There is a lot of useless flags to set to be able to build the PE file, but I didn't find another way to do it.

[jhenderson]

Some inline comment nits, and one thing I noticed regarding the "not implemented" part.

test/tools/llvm-objdump/file-headers-pe.test

10

those -> these

Also add a full stop at the end of the line.

11–12

All ... picked. They can't interfere ... here.

(i.e. remove extra "values", change comma to full stop, fix typo, add trailing full stop).

28

May be worth moving this particular field above the comment, since it is an important part of the test.

tools/llvm-objdump/llvm-objdump.cpp

2135

Hmmm... Should this use report_error? Or is not implemented normally reported on stdout?

Also, how easy is to get a test that hits this case? If it's simple, I think it should have one. If not, no need to write a complicated one.

[jhenderson]

test/tools/llvm-objdump/file-headers-coff.test

3

One more thing: since --file-headers is an alias of -f, I'd like to see both tested, to show they do the same thing. It should just be a case of duplicating this line in each of the tests, but with the other version of the switch (the same goes with other similar changes, such as D48904).

[paulsemel]

Added Jame's suggestions

[jhenderson]

LGTM, with the remaining two nits fixed.

test/tools/llvm-objdump/file-headers-error.test

1 ↗

(On Diff #154087)

I'd rename this file to file-headers-unsupported to better convey what is tested here.

test/tools/llvm-objdump/file-headers-pe.test

11–12

Still got a typo: interfer -> interfere

[paulsemel]

Should I land ?

[jhenderson]

In D48810#1152095, @paulsemel wrote:

Should I land ?

I don't see why not. It's not controversial, as far as I can tell.

[paulsemel]

Forgot to add Differential Revision in the commit, closing the revision

include/llvm/Object/COFF.h

public:
   COFFSymbolRef getCOFFSymbol(const SymbolRef &Symbol) const;
   const coff_relocation *getCOFFRelocation(const RelocationRef &Reloc) const;
   unsigned getSectionID(SectionRef Sec) const;
   unsigned getSymbolSectionID(SymbolRef Sym) const;
 
   uint8_t getBytesInAddress() const override;
   StringRef getFileFormatName() const override;
   Triple::ArchType getArch() const override;
+  Expected<uint64_t> getStartAddress() const override;
   SubtargetFeatures getFeatures() const override { return SubtargetFeatures(); }
 
   import_directory_iterator import_directory_begin() const;
   import_directory_iterator import_directory_end() const;
   delay_import_directory_iterator delay_import_directory_begin() const;
   delay_import_directory_iterator delay_import_directory_end() const;
   export_directory_iterator export_directory_begin() const;
   export_directory_iterator export_directory_end() const;

include/llvm/Object/ELFObjectFile.h

public:
   section_iterator section_begin() const override;
   section_iterator section_end() const override;
 
   Expected<int64_t> getRelocationAddend(DataRefImpl Rel) const override;
 
   uint8_t getBytesInAddress() const override;
   StringRef getFileFormatName() const override;
   Triple::ArchType getArch() const override;
+  Expected<uint64_t> getStartAddress() const override;
 
   unsigned getPlatformFlags() const override { return EF.getHeader()->e_flags; }
 
   std::error_code getBuildAttributes(ARMAttributeParser &Attributes) const override {
     auto SectionsOrErr = EF.sections();
     if (!SectionsOrErr)
       return errorToErrorCode(SectionsOrErr.takeError());
 
case ELF::EM_BPF:
     return IsLittleEndian ? Triple::bpfel : Triple::bpfeb;
 
   default:
     return Triple::UnknownArch;
   }
 }
 
 template <class ELFT>
+Expected<uint64_t> ELFObjectFile<ELFT>::getStartAddress() const {
+  return EF.getHeader()->e_entry;
+}
+
+template <class ELFT>
 ELFObjectFileBase::elf_symbol_iterator_range
 ELFObjectFile<ELFT>::getDynamicSymbolIterators() const {
   return make_range(dynamic_symbol_begin(), dynamic_symbol_end());
 }
 
 template <class ELFT> bool ELFObjectFile<ELFT>::isRelocatableObject() const {
   return EF.getHeader()->e_type == ELF::ET_REL;
 }
 
 } // end namespace object
 } // end namespace llvm
 
 #endif // LLVM_OBJECT_ELFOBJECTFILE_H

include/llvm/Object/ObjectFile.h

public:
   /// The number of bytes used to represent an address in this object
   ///        file format.
   virtual uint8_t getBytesInAddress() const = 0;
 
   virtual StringRef getFileFormatName() const = 0;
   virtual Triple::ArchType getArch() const = 0;
   virtual SubtargetFeatures getFeatures() const = 0;
   virtual void setARMSubArch(Triple &TheTriple) const { }
+  virtual Expected<uint64_t> getStartAddress() const {
+    return errorCodeToError(object_error::parse_failed);
+  };
 
   /// Create a triple from the data in this object file.
   Triple makeTriple() const;
 
   virtual std::error_code
     getBuildAttributes(ARMAttributeParser &Attributes) const {
       return std::error_code();
     }

lib/Object/COFFObjectFile.cpp

case COFF::IMAGE_FILE_MACHINE_ARMNT:
     return Triple::thumb;
   case COFF::IMAGE_FILE_MACHINE_ARM64:
     return Triple::aarch64;
   default:
     return Triple::UnknownArch;
   }
 }
 
+Expected<uint64_t> COFFObjectFile::getStartAddress() const {
+  if (PE32Header)
+    return PE32Header->AddressOfEntryPoint;
+  return 0;
+}
+
 iterator_range<import_directory_iterator>
 COFFObjectFile::import_directories() const {
   return make_range(import_directory_begin(), import_directory_end());
 }
 
 iterator_range<delay_import_directory_iterator>
 COFFObjectFile::delay_import_directories() const {
   return make_range(delay_import_directory_begin(),

test/tools/llvm-objdump/file-headers-coff.test

+# RUN: yaml2obj %s > %t
+# RUN: llvm-objdump -f %t | FileCheck %s
+# RUN: llvm-objdump -file-headers %t | FileCheck %s
+
+!COFF
+header: !Header
+  Machine: IMAGE_FILE_MACHINE_I386 # (0x14c)
+  Characteristics: [ IMAGE_FILE_DEBUG_STRIPPED ]
+sections:
+symbols:
+
+# CHECK: architecture: i386
+# CHECK: start address: 0x0000

test/tools/llvm-objdump/file-headers-elf.test

+# RUN: yaml2obj %s > %t
+# RUN: llvm-objdump -f %t | FileCheck %s
+# RUN: llvm-objdump -file-headers %t | FileCheck %s
+
+!ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_REL
+  Machine:         EM_X86_64
+  Entry:           0x123456
+
+# CHECK: architecture: x86_64
+# CHECK: start address: 0x00123456

test/tools/llvm-objdump/file-headers-pe.test

+# RUN: yaml2obj %s > %t
+# RUN: llvm-objdump -f %t | FileCheck %s
+# RUN: llvm-objdump -file-headers %t | FileCheck %s
+
+!COFF
+header: !Header
+  Machine: IMAGE_FILE_MACHINE_I386
+  Characteristics: [ IMAGE_FILE_DEBUG_STRIPPED ]
+OptionalHeader:
+  AddressOfEntryPoint: 0x1234
+# Unfortunately, all these flags are mandatory to set AddressOfEntryPoint.
+# All the values are randomly picked. They can't interfere in what
+# we are testing here.
+  SizeOfHeapCommit: 1024
+  SizeOfHeapReserve: 1024
+  SizeOfStackCommit: 1024
+  SizeOfStackReserve: 1024
+  DLLCharacteristics: [ IMAGE_DLL_CHARACTERISTICS_DYNAMIC_BASE ]
+  Subsystem: IMAGE_SUBSYSTEM_NATIVE
+  MinorSubsystemVersion: 1
+  MajorSubsystemVersion: 1
+  MinorImageVersion: 1
+  MajorImageVersion: 1
+  MinorOperatingSystemVersion: 1
+  MajorOperatingSystemVersion: 1
+  FileAlignment: 8
+  SectionAlignment: 8
+  ImageBase: 0x12
+sections:
+symbols:
+
+# CHECK: architecture: i386
+# CHECK: start address: 0x1234

test/tools/llvm-objdump/file-headers-unsupported.test

+# RUN: not llvm-objdump -file-headers %p/Inputs/trivial.obj.wasm 2>&1 | FileCheck %s
+
+# CHECK: Invalid/Unsupported object file format

tools/llvm-objdump/llvm-objdump.h

 extern cl::list<std::string> MAttrs;
 extern cl::list<std::string> FilterSections;
 extern cl::opt<bool> AllHeaders;
 extern cl::opt<bool> Disassemble;
 extern cl::opt<bool> DisassembleAll;
 extern cl::opt<bool> NoShowRawInsn;
 extern cl::opt<bool> NoLeadingAddr;
 extern cl::opt<bool> PrivateHeaders;
+extern cl::opt<bool> FileHeaders;
 extern cl::opt<bool> FirstPrivateHeader;
 extern cl::opt<bool> ExportsTrie;
 extern cl::opt<bool> Rebase;
 extern cl::opt<bool> Bind;
 extern cl::opt<bool> LazyBind;
 extern cl::opt<bool> WeakBind;
 extern cl::opt<bool> RawClangAST;
 extern cl::opt<bool> UniversalHeaders;

tools/llvm-objdump/llvm-objdump.cpp

 llvm::FirstPrivateHeader("private-header",
                          cl::desc("Display only the first format specific file "
                                   "header"));
 
 static cl::alias
 PrivateHeadersShort("p", cl::desc("Alias for --private-headers"),
                     cl::aliasopt(PrivateHeaders));
 
+cl::opt<bool> llvm::FileHeaders(
+    "file-headers",
+    cl::desc("Display the contents of the overall file header"));
+
+static cl::alias FileHeadersShort("f", cl::desc("Alias for --file-headers"),
+                                  cl::aliasopt(FileHeaders));
+
 cl::opt<bool>
     llvm::PrintImmHex("print-imm-hex",
                       cl::desc("Use hex format for immediate values"));
 
 cl::opt<bool> PrintFaultMaps("fault-map-section",
                              cl::desc("Display contents of faultmap section"));
 
 cl::opt<DIDumpType> llvm::DwarfDumpType(
if (o->isMachO()) {
     printMachOFileHeader(o);
     if (!onlyFirst)
       printMachOLoadCommands(o);
     return;
   }
   report_error(o->getFileName(), "Invalid/Unsupported object file format");
 }
 
+static void printFileHeaders(const ObjectFile *o) {
+  if (!o->isELF() && !o->isCOFF())
+    report_error(o->getFileName(), "Invalid/Unsupported object file format");
+
+  Triple::ArchType AT = o->getArch();
+  outs() << "architecture: " << Triple::getArchTypeName(AT) << "\n";
+  Expected<uint64_t> StartAddrOrErr = o->getStartAddress();
+  if (!StartAddrOrErr)
+    report_error(o->getFileName(), StartAddrOrErr.takeError());
+  outs() << "start address: "
+         << format("0x%0*x", o->getBytesInAddress(), StartAddrOrErr.get())
+         << "\n";
+}
+
 static void DumpObject(ObjectFile *o, const Archive *a = nullptr) {
   StringRef ArchiveName = a != nullptr ? a->getFileName() : "";
   // Avoid other output when using a raw option.
   if (!RawClangAST) {
     outs() << '\n';
     if (a)
       outs() << a->getFileName() << "(" << o->getFileName() << ")";
     else
static void DumpObject(ObjectFile *o, const Archive *a = nullptr) {
   if (SectionContents)
     PrintSectionContents(o);
   if (SymbolTable)
     PrintSymbolTable(o, ArchiveName);
   if (UnwindInfo)
     PrintUnwindInfo(o);
   if (PrivateHeaders || FirstPrivateHeader)
     printPrivateFileHeaders(o, FirstPrivateHeader);
+  if (FileHeaders)
+    printFileHeaders(o);
   if (ExportsTrie)
     printExportsTrie(o);
   if (Rebase)
     printRebaseTable(o);
   if (Bind)
     printBindTable(o);
   if (LazyBind)
     printLazyBindTable(o);
int main(int argc, char **argv) {
   if (!Disassemble
       && !Relocations
       && !DynamicRelocations
       && !SectionHeaders
       && !SectionContents
       && !SymbolTable
       && !UnwindInfo
       && !PrivateHeaders
+      && !FileHeaders
       && !FirstPrivateHeader
       && !ExportsTrie
       && !Rebase
       && !Bind
       && !LazyBind
       && !WeakBind
       && !RawClangAST
       && !(UniversalHeaders && MachOOpt)
       && !(ArchiveHeaders && MachOOpt)
       && !(IndirectSymbols && MachOOpt)
       && !(DataInCode && MachOOpt)
       && !(LinkOptHints && MachOOpt)
       && !(InfoPlist && MachOOpt)
       && !(DylibsUsed && MachOOpt)
       && !(DylibId && MachOOpt)
       && !(ObjcMetaData && MachOOpt)
       && !(FilterSections.size() != 0 && MachOOpt)
       && !PrintFaultMaps
       && DwarfDumpType == DIDT_Null) {
     cl::PrintHelpMessage();
     return 2;
   }
 
   DisasmFuncsSet.insert(DisassembleFunctions.begin(),
                         DisassembleFunctions.end());
 
   llvm::for_each(InputFilenames, DumpInput);
 
   return EXIT_SUCCESS;
 }