Teach llvm-readobj to dump symbol records from a DEBUG_SYMBOL_SUBSECTION section.

[zturner]

Summary

Subsections of type DEBUG_SYMBOL_SUBSECTION consist of a series of records. Each record begins with a 4 byte length, followed by 4 byte type, followed by <length> bytes of data.

This was already known, but we only dumped DEBUG_SYMBOL_TYPE_PROC_START and DEBUG_SYMBOL_TYPE_PROC_END. This patch makes llvm-readobj dump the Length, type, and payload of other types of entries as individaul records so that they can be studied more closely.

[zturner]

The reason for removing references to "linetables" and moving towards the more generic "codeview" terminology is because the .debug$S section contains much more than just linetable information. Previously we were really only interested in the linetables, but I have interest in everything in the section now, and hope to soon be able to decipher some of the other type codes and dump them as well. Additionally, we will need to be able to dump the .debug$T section as well, which contains type information, so it seems appropriate to not call it "codeview linetable information" anymore and instead just call it "codeview debug information"

[timurrrr]

Changing scope and renaming: LGTM

You might want to reconsider some details after reading the comments.

tools/llvm-readobj/COFFDumper.cpp

509

We might want to put this under an if () (see the other comment at the deifinition of CodeViewSymbols)

701

nit: I suggest either

W.printHex("Size", Size);

or rename Size to Length?
Or SegmentSize?

tools/llvm-readobj/llvm-readobj.h

40

We might consider reusing SectionSymbols?

If the main purpose of CodeViewSymbols is to dump subsections we can't parse/dump yet, maybe we should use CodeViewDumpUnknownParts or something?

[zturner]

Update review with suggested changes.

[timurrrr]

tools/llvm-readobj/COFFDumper.cpp

509

I meant we might want to put the

W.printBinaryBlock("Contents", Contents);

line under a CodeViewSomethingUnknownSomething condition.

tools/llvm-readobj/llvm-readobj.h

40

might want to generalize to "CodeViewDumpUnknownRecords` or something.

[zturner]

Wasn't sure if the name is getting too long / annoying to type. But since I'm reusing the variable for both the bytes of the entire subsection, as well as the byets of the individual records, I think subsection-bytes more accurately describes the intent than something about "unknown". I don't feel strongly about the name though, so let me know if you prefer something else.

[timurrrr]

tools/llvm-readobj/COFFDumper.cpp

710

this indentation looks weird. Is it how clang-format formats this?

[zturner]

I think it's a consequence of us not indenting case labels. I'll double
check that i clang-formatted it later though

[timurrrr]

Thanks for the improvements in the dumper!

include/llvm/Support/COFF.h

ImportType getType() const {
       return static_cast<ImportType>(TypeInfo & 0x3);
     }
 
     ImportNameType getNameType() const {
       return static_cast<ImportNameType>((TypeInfo & 0x1C) >> 3);
     }
   };
 
-  enum CodeViewLineTableIdentifiers {
-    DEBUG_SECTION_MAGIC           = 0x4,
-    DEBUG_SYMBOL_SUBSECTION       = 0xF1,
-    DEBUG_LINE_TABLE_SUBSECTION   = 0xF2,
+  enum CodeViewIdentifiers {
+    DEBUG_SECTION_MAGIC = 0x4,
+    DEBUG_SYMBOL_SUBSECTION = 0xF1,
+    DEBUG_LINE_TABLE_SUBSECTION = 0xF2,
     DEBUG_STRING_TABLE_SUBSECTION = 0xF3,
-    DEBUG_INDEX_SUBSECTION        = 0xF4,
+    DEBUG_INDEX_SUBSECTION = 0xF4,
 
     // Symbol subsections are split into records of different types.
     DEBUG_SYMBOL_TYPE_PROC_START = 0x1147,
-    DEBUG_SYMBOL_TYPE_PROC_END   = 0x114F
+    DEBUG_SYMBOL_TYPE_PROC_END = 0x114F
   };
 
   inline bool isReservedSectionNumber(int32_t SectionNumber) {
     return SectionNumber <= 0;
   }
 
 } // End namespace COFF.
 } // End namespace llvm.
 
 #endif

test/tools/llvm-readobj/codeview-linetables.test

 ;   }
 ;
 ;   void f(void) {
 ;     x();
 ;     y();
 ;     z();
 ;   }
 ; using 32-/64-bit versions of CL v17.00.61030 and v18.00.21005.1 respectively.
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/multifunction-linetables.obj.coff-2012-i368 \
+RUN: llvm-readobj -s -codeview %p/Inputs/multifunction-linetables.obj.coff-2012-i368 \
 RUN:   | FileCheck %s -check-prefix MFUN32
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/multifunction-linetables.obj.coff-2013-i368 \
+RUN: llvm-readobj -s -codeview %p/Inputs/multifunction-linetables.obj.coff-2013-i368 \
 RUN:   | FileCheck %s -check-prefix MFUN32
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/multifunction-linetables.obj.coff-2012-x86_64 \
+RUN: llvm-readobj -s -codeview %p/Inputs/multifunction-linetables.obj.coff-2012-x86_64 \
 RUN:   | FileCheck %s -check-prefix MFUN64
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/multifunction-linetables.obj.coff-2013-x86_64 \
+RUN: llvm-readobj -s -codeview %p/Inputs/multifunction-linetables.obj.coff-2013-x86_64 \
 RUN:   | FileCheck %s -check-prefix MFUN64
 
-MFUN32:      CodeViewLineTables [
+MFUN32:      CodeViewDebugInfo [
 MFUN32-NEXT:   Magic: 0x4
 MFUN32-NEXT:   Subsection [
 MFUN32-NEXT:     Type: 0xF1
 MFUN32-NEXT:     PayloadSize: 0x52
 MFUN32:        ]
 MFUN32-NEXT:   Subsection [
 MFUN32-NEXT:     Type: 0xF5
 MFUN32-NEXT:     PayloadSize: 0x24

 MFUN32-NEXT:       +0x3: 12
 MFUN32-NEXT:       +0x8: 13
 MFUN32-NEXT:       +0xD: 14
 MFUN32-NEXT:       +0x12: 15
 MFUN32-NEXT:     ]
 MFUN32-NEXT:   ]
 MFUN32-NEXT: ]
 
-MFUN64:      CodeViewLineTables [
+MFUN64:      CodeViewDebugInfo [
 MFUN64-NEXT:   Magic: 0x4
 MFUN64-NEXT:   Subsection [
 MFUN64-NEXT:     Type: 0xF1
 MFUN64-NEXT:     PayloadSize: 0x52
 MFUN64:        ]
 MFUN64-NEXT:   Subsection [
 MFUN64-NEXT:     Type: 0xF1
 MFUN64-NEXT:     PayloadSize: 0x4B

 ;   #line 1 "one.c"
 ;     g();
 ;   #line 2 "two.c"
 ;     g();
 ;   #line 7 "one.c"
 ;     g();
 ;   }
 ; using 32-/64-bit versions of CL v17.00.61030 and v18.00.21005.1 respectively.
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/multifile-linetables.obj.coff-2012-i368 \
+RUN: llvm-readobj -s -codeview %p/Inputs/multifile-linetables.obj.coff-2012-i368 \
 RUN:   | FileCheck %s -check-prefix MFILE32
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/multifile-linetables.obj.coff-2013-i368 \
+RUN: llvm-readobj -s -codeview %p/Inputs/multifile-linetables.obj.coff-2013-i368 \
 RUN:   | FileCheck %s -check-prefix MFILE32
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/multifile-linetables.obj.coff-2012-x86_64 \
+RUN: llvm-readobj -s -codeview %p/Inputs/multifile-linetables.obj.coff-2012-x86_64 \
 RUN:   | FileCheck %s -check-prefix MFILE64
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/multifile-linetables.obj.coff-2013-x86_64 \
+RUN: llvm-readobj -s -codeview %p/Inputs/multifile-linetables.obj.coff-2013-x86_64 \
 RUN:   | FileCheck %s -check-prefix MFILE64
 
-MFILE32:      CodeViewLineTables [
+MFILE32:      CodeViewDebugInfo [
 MFILE32-NEXT:   Magic: 0x4
 MFILE32-NEXT:   Subsection [
 MFILE32-NEXT:     Type: 0xF1
 MFILE32-NEXT:     PayloadSize: 0x51
 MFILE32:        ]
 MFILE32-NEXT:   Subsection [
 MFILE32-NEXT:     Type: 0xF5
 MFILE32-NEXT:     PayloadSize: 0x24

 MFILE32-NEXT:     FilenameSegment [
 MFILE32-NEXT:       Filename: d:\one.c
 MFILE32-NEXT:       +0xD: 7
 MFILE32-NEXT:       +0x12: 8
 MFILE32-NEXT:     ]
 MFILE32-NEXT:   ]
 MFILE32-NEXT: ]
 
-MFILE64:      CodeViewLineTables [
+MFILE64:      CodeViewDebugInfo [
 MFILE64-NEXT:   Magic: 0x4
 MFILE64-NEXT:   Subsection [
 MFILE64-NEXT:     Type: 0xF1
 MFILE64-NEXT:     PayloadSize: 0x51
 MFILE64:        ]
 MFILE64-NEXT:   Subsection [
 MFILE64-NEXT:     Type: 0xF1
 MFILE64-NEXT:     PayloadSize: 0x4B

 ;     return 0;
 ;   }
 ;
 ;   int g()
 ;   {
 ;     return 0;
 ;   }
 ; using 32-version of CL v17.00.61030 and v18.00.21005.1 respectively.
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/comdat-function-linetables.obj.coff-2012-i386 \
+RUN: llvm-readobj -s -codeview %p/Inputs/comdat-function-linetables.obj.coff-2012-i386 \
 RUN:   | FileCheck %s -check-prefix MCOMDAT
-RUN: llvm-readobj -s -codeview-linetables %p/Inputs/comdat-function-linetables.obj.coff-2013-i386 \
+RUN: llvm-readobj -s -codeview %p/Inputs/comdat-function-linetables.obj.coff-2013-i386 \
 RUN:   | FileCheck %s -check-prefix MCOMDAT
 
 MCOMDAT:      ProcStart {
 MCOMDAT-NEXT:   DisplayName: f
 MCOMDAT-NEXT:   Section: ?f@@YAHXZ
 MCOMDAT-NEXT:   CodeSize: 0x7
 MCOMDAT-NEXT: }
 MCOMDAT:      FunctionLineTable [

tools/llvm-readobj/COFFDumper.cpp

private:
   void printRelocation(const SectionRef &Section, const RelocationRef &Reloc);
   void printDataDirectory(uint32_t Index, const std::string &FieldName);
 
   void printDOSHeader(const dos_header *DH);
   template <class PEHeader> void printPEHeader(const PEHeader *Hdr);
   void printBaseOfDataField(const pe32_header *Hdr);
   void printBaseOfDataField(const pe32plus_header *Hdr);
 
-  void printCodeViewLineTables(const SectionRef &Section);
+  void printCodeViewDebugInfo(const SectionRef &Section);
 
   void printCodeViewSymbolsSubsection(StringRef Subsection,
                                       const SectionRef &Section,
                                       uint32_t Offset);
 
   void cacheRelocations();
 
   std::error_code resolveSymbol(const coff_section *Section, uint64_t Offset,

 }
 
 void COFFDumper::printBaseOfDataField(const pe32_header *Hdr) {
   W.printHex("BaseOfData", Hdr->BaseOfData);
 }
 
 void COFFDumper::printBaseOfDataField(const pe32plus_header *) {}
 
-void COFFDumper::printCodeViewLineTables(const SectionRef &Section) {
+void COFFDumper::printCodeViewDebugInfo(const SectionRef &Section) {
   StringRef Data;
   if (error(Section.getContents(Data)))
     return;
 
   SmallVector<StringRef, 10> FunctionNames;
   StringMap<StringRef> FunctionLineTables;
 
-  ListScope D(W, "CodeViewLineTables");
+  ListScope D(W, "CodeViewDebugInfo");
   {
     // FIXME: Add more offset correctness checks.
     DataExtractor DE(Data, true, 4);
     uint32_t Offset = 0,
              Magic = DE.getU32(&Offset);
     W.printHex("Magic", Magic);
     if (Magic != COFF::DEBUG_SECTION_MAGIC) {
       error(object_error::parse_failed);
while (DE.isValidOffset(Offset) && !Finished) {
       if (PayloadSize > Data.size() - Offset) {
         error(object_error::parse_failed);
         return;
       }
 
       // Print the raw contents to simplify debugging if anything goes wrong
       // afterwards.
       StringRef Contents = Data.substr(Offset, PayloadSize);
       W.printBinaryBlock("Contents", Contents);
 
       switch (SubSectionType) {
       case COFF::DEBUG_SYMBOL_SUBSECTION:
         printCodeViewSymbolsSubsection(Contents, Section, Offset);
         break;
       case COFF::DEBUG_LINE_TABLE_SUBSECTION: {
         // Holds a PC to file:line table.  Some data to parse this subsection is
         // stored in the other subsections, so just check sanity and store the
case COFF::DEBUG_SYMBOL_TYPE_PROC_END: {
       if (!InFunctionScope || Size > 0) {
         error(object_error::parse_failed);
         return;
       }
       InFunctionScope = false;
       break;
     }
     default:
+      if (opts::CodeViewSymbols) {
+        ListScope S(W, "Record");
+        W.printHex("Length", Size);
+        W.printHex("Type", Type);
+
+        StringRef Contents = DE.getData().substr(Offset, Size);
+        W.printBinaryBlock("Contents", Contents);
+      }
+
       Offset += Size;
       break;
     }
   }
 
   if (InFunctionScope)
     error(object_error::parse_failed);
 }
 
 void COFFDumper::printSections() {
   ListScope SectionsD(W, "Sections");
if (opts::SectionSymbols) {
       for (const SymbolRef &Symbol : Obj->symbols()) {
         if (!Sec.containsSymbol(Symbol))
           continue;
 
         printSymbol(Symbol);
       }
     }
 
-    if (Name == ".debug$S" && opts::CodeViewLineTables)
-      printCodeViewLineTables(Sec);
+    if (Name == ".debug$S" && opts::CodeView)
+      printCodeViewDebugInfo(Sec);
 
     if (opts::SectionData &&
         !(Section->Characteristics & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA)) {
       StringRef Data;
       if (error(Sec.getContents(Data)))
         break;
 
       W.printBinaryBlock("SectionData", Data);

tools/llvm-readobj/llvm-readobj.h

namespace opts {
   extern llvm::cl::opt<bool> SectionRelocations;
   extern llvm::cl::opt<bool> SectionSymbols;
   extern llvm::cl::opt<bool> SectionData;
   extern llvm::cl::opt<bool> Relocations;
   extern llvm::cl::opt<bool> Symbols;
   extern llvm::cl::opt<bool> DynamicSymbols;
   extern llvm::cl::opt<bool> UnwindInfo;
   extern llvm::cl::opt<bool> ExpandRelocs;
-  extern llvm::cl::opt<bool> CodeViewLineTables;
+  extern llvm::cl::opt<bool> CodeView;
+  extern llvm::cl::opt<bool> CodeViewSymbols;
   extern llvm::cl::opt<bool> ARMAttributes;
   extern llvm::cl::opt<bool> MipsPLTGOT;
 } // namespace opts
 
 #define LLVM_READOBJ_ENUM_ENT(ns, enum) \
   { #enum, ns::enum }
 
 #endif

tools/llvm-readobj/llvm-readobj.cpp

namespace opts {
   // -program-headers
   cl::opt<bool> ProgramHeaders("program-headers",
     cl::desc("Display ELF program headers"));
 
   // -expand-relocs
   cl::opt<bool> ExpandRelocs("expand-relocs",
     cl::desc("Expand each shown relocation to multiple lines"));
 
-  // -codeview-linetables
-  cl::opt<bool> CodeViewLineTables("codeview-linetables",
-    cl::desc("Display CodeView line table information"));
+  // -codeview
+  cl::opt<bool> CodeView("codeview",
+                         cl::desc("Display CodeView debug information"));
+
+  // -codeview-symbols
+  cl::opt<bool> CodeViewSymbols("codeview-symbols",
+                                cl::desc("Display CodeView symbol records"));
 
   // -arm-attributes, -a
   cl::opt<bool> ARMAttributes("arm-attributes",
                               cl::desc("Display the ARM attributes section"));
   cl::alias ARMAttributesShort("-a", cl::desc("Alias for --arm-attributes"),
                                cl::aliasopt(ARMAttributes));
 
   // -mips-plt-got