[DWARF] Modification of code for the verification of .debug_info section.

[sgravani]

Summary

This patch modifies the handleDebugInfo() function so that we verify the contents of each unit
in the .debug_info section only if its header has been successfully verified.

This change will allow for more/different verification checks depending on the type of the unit since from
dwarf5, the .debug_info section may consist of different types of units.

[sgravani]

Minor, yet very important, change to the previous diff.
OffsetStart has to be equal to the beginning of the unit before verifying the contents of the unit...

[sgravani]

This is the diff from the trunk..

I made a mistake in my previous update and submitted the diff from the previous revision.

[aprantl]

lib/DebugInfo/DWARF/DWARFVerifier.cpp

95

Since Tag isn't used anywhere else:
if (Die.getTag() == DW_TAG_null)

102

It looks like this might also return false if the unit is correct, but there were previous errors? Is that what we want here?

141

I think it might be better to handle the default: case separately and have it produce a verification error.

167

Same point applies as in line 101, though here it looks more like this is intentional.

[sgravani]

Addressed reviewer's comments.

lib/DebugInfo/DWARF/DWARFVerifier.cpp

102

No this is not what we want. We want to know if each unit has errors or not.
I fixed it, thanks.

141

I think what makes the best sense here is to handle the cases for all valid types and UnitType = 0 ( meaning that we are verifying a compile unit in dwarf4 version), and have llvm_unreachable() for default case.

[sgravani]

Addressed comments.
Added test case for verifying a "mix" of units in the .debug_info section.
The first unit has an invalid DIE, the second unit passes verification and the third unit has an invalid length.

[aprantl]

LGTM with outstanding changes applied. Thanks!

lib/DebugInfo/DWARF/DWARFVerifier.cpp

142

-> for consistency: in DWARF v4.

172

Perhaps return the number of errors:

unsigned DWARFVerifier::verifyDebugInfoAttribute(const DWARFDie &Die, DWARFAttribute &AttrValue);

285

same here

[sgravani]

Closed with commit: rL308245

include/llvm/DebugInfo/DWARF/DWARFVerifier.h

 /// A class that verifies DWARF debug information given a DWARF Context.
 class DWARFVerifier {
   raw_ostream &OS;
   DWARFContext &DCtx;
   /// A map that tracks all references (converted absolute references) so we
   /// can verify each reference points to a valid DIE and not an offset that
   /// lies between to valid DIEs.
   std::map<uint64_t, std::set<uint32_t>> ReferenceToDIEOffsets;
-  uint32_t NumDebugInfoErrors = 0;
   uint32_t NumDebugLineErrors = 0;
   uint32_t NumAppleNamesErrors = 0;
 
   /// Verifies the header of a unit in the .debug_info section.
   ///
   /// This function currently checks for:
   /// - Unit is in 32-bit DWARF format. The function can be modified to
   /// support 64-bit format.
   /// - The DWARF version is valid
   /// - The unit type is valid (if unit is in version >=5)
   /// - The unit doesn't extend beyond .debug_info section
   /// - The address size is valid
   /// - The offset in the .debug_abbrev section is valid
   ///
   /// \param DebugInfoData The .debug_info section data
   /// \param Offset A reference to the offset start of the unit. The offset will
   /// be updated to point to the next unit in .debug_info
   /// \param UnitIndex The index of the unit to be verified
+  /// \param UnitType A reference to the type of the unit
   /// \param isUnitDWARF64 A reference to a flag that shows whether the unit is
   /// in 64-bit format.
   ///
   /// \returns true if the header is verified successfully, false otherwise.
   bool verifyUnitHeader(const DWARFDataExtractor DebugInfoData,
-                        uint32_t *Offset, unsigned UnitIndex,
+                        uint32_t *Offset, unsigned UnitIndex, uint8_t &UnitType,
                         bool &isUnitDWARF64);
 
+  bool verifyUnitContents(DWARFUnit Unit);
   /// Verifies the attribute's DWARF attribute and its value.
   ///
   /// This function currently checks for:
   /// - DW_AT_ranges values is a valid .debug_ranges offset
   /// - DW_AT_stmt_list is a valid .debug_line offset
   ///
   /// \param Die          The DWARF DIE that owns the attribute value
   /// \param AttrValue    The DWARF attribute value to check
-  void verifyDebugInfoAttribute(const DWARFDie &Die, DWARFAttribute &AttrValue);
+  /// \param NumUnitErrors Reference to the number of errors for the unit that
+  /// is currently being verified
+  void verifyDebugInfoAttribute(const DWARFDie &Die, DWARFAttribute &AttrValue,
+                                uint32_t &NumUnitErrors);
 
   /// Verifies the attribute's DWARF form.
   ///
   /// This function currently checks for:
   /// - All DW_FORM_ref values that are CU relative have valid CU offsets
   /// - All DW_FORM_ref_addr values have valid .debug_info offsets
   /// - All DW_FORM_strp values have valid .debug_str offsets
   ///
   /// \param Die          The DWARF DIE that owns the attribute value
   /// \param AttrValue    The DWARF attribute value to check
-  void verifyDebugInfoForm(const DWARFDie &Die, DWARFAttribute &AttrValue);
+  /// \param NumUnitErrors Reference to the number of errors for the unit that
+  /// is currently being verified
+  void verifyDebugInfoForm(const DWARFDie &Die, DWARFAttribute &AttrValue,
+                           uint32_t &NumUnitErrors);
 
   /// Verifies the all valid references that were found when iterating through
   /// all of the DIE attributes.
   ///
   /// This function will verify that all references point to DIEs whose DIE
   /// offset matches. This helps to ensure if a DWARF link phase moved things
   /// around, that it doesn't create invalid references by failing to relocate
   /// CU relative and absolute references.
-  void verifyDebugInfoReferences();
+  ///
+  /// \param NumDebugInfoErrors Reference to the number of errors for the
+  /// .debug_info section
+  void verifyDebugInfoReferences(uint32_t &NumDebugInfoErrors);
 
   /// Verify the the DW_AT_stmt_list encoding and value and ensure that no
   /// compile units that have the same DW_AT_stmt_list value.
   void verifyDebugLineStmtOffsets();
 
   /// Verify that all of the rows in the line table are valid.
   ///
   /// This function currently checks for:
   /// - addresses within a sequence that decrease in value
   /// - invalid file indexes
   void verifyDebugLineRows();
 
 public:
   DWARFVerifier(raw_ostream &S, DWARFContext &D)
       : OS(S), DCtx(D) {}
-  /// Verify the unit header chain in the .debug_info section.
-  ///
-  /// Any errors are reported to the stream that this object was
-  /// constructed with.
-  ///
-  /// \returns true if the unit header chain verifies successfully, false
-  /// otherwise.
-  bool handleDebugInfoUnitHeaderChain();
   /// Verify the information in the .debug_info section.
   ///
   /// Any errors are reported to the stream that was this object was
   /// constructed with.
   ///
   /// \returns true if the .debug_info verifies successfully, false otherwise.
   bool handleDebugInfo();
 

lib/DebugInfo/DWARF/DWARFContext.cpp

DWARFDie DWARFContext::getDIEForOffset(uint32_t Offset) {
   if (auto *CU = CUs.getUnitForOffset(Offset))
     return CU->getDIEForOffset(Offset);
   return DWARFDie();
 }
 
 bool DWARFContext::verify(raw_ostream &OS, DIDumpType DumpType) {
   bool Success = true;
   DWARFVerifier verifier(OS, *this);
-  if (!verifier.handleDebugInfoUnitHeaderChain())
-    Success = false;
   if (DumpType == DIDT_All || DumpType == DIDT_Info) {
     if (!verifier.handleDebugInfo())
       Success = false;
   }
   if (DumpType == DIDT_All || DumpType == DIDT_Line) {
     if (!verifier.handleDebugLine())
       Success = false;
   }

lib/DebugInfo/DWARF/DWARFVerifier.cpp

 #include <set>
 #include <vector>
 
 using namespace llvm;
 using namespace dwarf;
 using namespace object;
 
 bool DWARFVerifier::verifyUnitHeader(const DWARFDataExtractor DebugInfoData,
                                      uint32_t *Offset, unsigned UnitIndex,
-                               bool &isUnitDWARF64) {
+                                     uint8_t &UnitType, bool &isUnitDWARF64) {
   uint32_t AbbrOffset, Length;
-  uint8_t AddrSize = 0, UnitType = 0;
+  uint8_t AddrSize = 0;
   uint16_t Version;
   bool Success = true;
 
   bool ValidLength = false;
   bool ValidVersion = false;
   bool ValidAddrSize = false;
   bool ValidType = true;
   bool ValidAbbrevOffset = true;
bool DWARFVerifier::verifyUnitHeader(const DWARFDataExtractor DebugInfoData,
   Version = DebugInfoData.getU16(Offset);
 
   if (Version >= 5) {
     UnitType = DebugInfoData.getU8(Offset);
     AddrSize = DebugInfoData.getU8(Offset);
     AbbrOffset = DebugInfoData.getU32(Offset);
     ValidType = DWARFUnit::isValidUnitType(UnitType);
   } else {
+    UnitType = 0;
     AbbrOffset = DebugInfoData.getU32(Offset);
     AddrSize = DebugInfoData.getU8(Offset);
   }
 
   if (!DCtx.getDebugAbbrev()->getAbbreviationDeclarationSet(AbbrOffset))
     ValidAbbrevOffset = false;
 
   ValidLength = DebugInfoData.isValidOffset(OffsetStart + Length + 3);
if (!ValidAbbrevOffset)
             "not valid.\n";
     if (!ValidAddrSize)
       OS << "\tError: The address size is unsupported.\n";
   }
   *Offset = OffsetStart + Length + 4;
   return Success;
 }
 
-bool DWARFVerifier::handleDebugInfoUnitHeaderChain() {
+bool DWARFVerifier::verifyUnitContents(DWARFUnit Unit) {
+  uint32_t NumUnitErrors = 0;
+  unsigned NumDies = Unit.getNumDIEs();
+  for (unsigned I = 0; I < NumDies; ++I) {
+    auto Die = Unit.getDIEAtIndex(I);
+    if (Die.getTag() == DW_TAG_null)
+      continue;
+    for (auto AttrValue : Die.attributes()) {
+      verifyDebugInfoAttribute(Die, AttrValue, NumUnitErrors);
+      verifyDebugInfoForm(Die, AttrValue, NumUnitErrors);
+    }
+  }
+  return NumUnitErrors == 0;
+}
+
+bool DWARFVerifier::handleDebugInfo() {
   OS << "Verifying .debug_info Unit Header Chain...\n";
 
   DWARFDataExtractor DebugInfoData(DCtx.getInfoSection(), DCtx.isLittleEndian(),
                                    0);
-  uint32_t Offset = 0, UnitIdx = 0;
+  uint32_t NumDebugInfoErrors = 0;
+  uint32_t OffsetStart = 0, Offset = 0, UnitIdx = 0;
+  uint8_t UnitType = 0;
   bool isUnitDWARF64 = false;
-  bool Success = true;
+  bool isHeaderChainValid = true;
   bool hasDIE = DebugInfoData.isValidOffset(Offset);
   while (hasDIE) {
-    if (!verifyUnitHeader(DebugInfoData, &Offset, UnitIdx, isUnitDWARF64)) {
-      Success = false;
+    OffsetStart = Offset;
+    if (!verifyUnitHeader(DebugInfoData, &Offset, UnitIdx, UnitType,
+                          isUnitDWARF64)) {
+      isHeaderChainValid = false;
       if (isUnitDWARF64)
         break;
+    } else {
+      std::unique_ptr<DWARFUnit> Unit;
+      switch (UnitType) {
+      case dwarf::DW_UT_type:
+      case dwarf::DW_UT_split_type: {
+        DWARFUnitSection<DWARFTypeUnit> TUSection{};
+        Unit.reset(new DWARFTypeUnit(
+            DCtx, DCtx.getInfoSection(), DCtx.getDebugAbbrev(),
+            &DCtx.getRangeSection(), DCtx.getStringSection(),
+            DCtx.getStringOffsetSection(), &DCtx.getAppleObjCSection(),
+            DCtx.getLineSection(), DCtx.isLittleEndian(), false, TUSection,
+            nullptr));
+        break;
+      }
+      case dwarf::DW_UT_skeleton:
+      case dwarf::DW_UT_split_compile:
+      case dwarf::DW_UT_compile:
+      case dwarf::DW_UT_partial:
+      // UnitType = 0 means that we are
+      // verifying a compile unit in dwarf4 version.
+      case 0: {
+        DWARFUnitSection<DWARFCompileUnit> CUSection{};
+        Unit.reset(new DWARFCompileUnit(
+            DCtx, DCtx.getInfoSection(), DCtx.getDebugAbbrev(),
+            &DCtx.getRangeSection(), DCtx.getStringSection(),
+            DCtx.getStringOffsetSection(), &DCtx.getAppleObjCSection(),
+            DCtx.getLineSection(), DCtx.isLittleEndian(), false, CUSection,
+            nullptr));
+        break;
+      }
+      default: { llvm_unreachable("Invalid UnitType."); }
+      }
+      Unit->extract(DebugInfoData, &OffsetStart);
+      if (!verifyUnitContents(*Unit))
+        ++NumDebugInfoErrors;
     }
     hasDIE = DebugInfoData.isValidOffset(Offset);
     ++UnitIdx;
   }
   if (UnitIdx == 0 && !hasDIE) {
     OS << "Warning: .debug_info is empty.\n";
-    Success = true;
+    isHeaderChainValid = true;
   }
-  return Success;
+  verifyDebugInfoReferences(NumDebugInfoErrors);
+  return (isHeaderChainValid && NumDebugInfoErrors == 0);
 }
 
 void DWARFVerifier::verifyDebugInfoAttribute(const DWARFDie &Die,
-                                             DWARFAttribute &AttrValue) {
+                                             DWARFAttribute &AttrValue,
+                                             uint32_t &NumUnitErrors) {
   const auto Attr = AttrValue.Attr;
   switch (Attr) {
   case DW_AT_ranges:
     // Make sure the offset in the DW_AT_ranges attribute is valid.
     if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
       if (*SectionOffset >= DCtx.getRangeSection().Data.size()) {
-        ++NumDebugInfoErrors;
+        ++NumUnitErrors;
         OS << "error: DW_AT_ranges offset is beyond .debug_ranges "
               "bounds:\n";
         Die.dump(OS, 0);
         OS << "\n";
       }
     } else {
-      ++NumDebugInfoErrors;
+      ++NumUnitErrors;
       OS << "error: DIE has invalid DW_AT_ranges encoding:\n";
       Die.dump(OS, 0);
       OS << "\n";
     }
     break;
   case DW_AT_stmt_list:
     // Make sure the offset in the DW_AT_stmt_list attribute is valid.
     if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
       if (*SectionOffset >= DCtx.getLineSection().Data.size()) {
-        ++NumDebugInfoErrors;
+        ++NumUnitErrors;
         OS << "error: DW_AT_stmt_list offset is beyond .debug_line "
               "bounds: "
            << format("0x%08" PRIx32, *SectionOffset) << "\n";
         Die.dump(OS, 0);
         OS << "\n";
       }
     } else {
-      ++NumDebugInfoErrors;
+      ++NumUnitErrors;
       OS << "error: DIE has invalid DW_AT_stmt_list encoding:\n";
       Die.dump(OS, 0);
       OS << "\n";
     }
     break;
 
   default:
     break;
   }
 }
 
 void DWARFVerifier::verifyDebugInfoForm(const DWARFDie &Die,
-                                        DWARFAttribute &AttrValue) {
+                                        DWARFAttribute &AttrValue,
+                                        uint32_t &NumUnitErrors) {
   const auto Form = AttrValue.Value.getForm();
   switch (Form) {
   case DW_FORM_ref1:
   case DW_FORM_ref2:
   case DW_FORM_ref4:
   case DW_FORM_ref8:
   case DW_FORM_ref_udata: {
     // Verify all CU relative references are valid CU offsets.
     Optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
     assert(RefVal);
     if (RefVal) {
       auto DieCU = Die.getDwarfUnit();
       auto CUSize = DieCU->getNextUnitOffset() - DieCU->getOffset();
       auto CUOffset = AttrValue.Value.getRawUValue();
       if (CUOffset >= CUSize) {
-        ++NumDebugInfoErrors;
+        ++NumUnitErrors;
         OS << "error: " << FormEncodingString(Form) << " CU offset "
            << format("0x%08" PRIx32, CUOffset)
            << " is invalid (must be less than CU size of "
            << format("0x%08" PRIx32, CUSize) << "):\n";
         Die.dump(OS, 0);
         OS << "\n";
       } else {
         // Valid reference, but we will verify it points to an actual
         // DIE later.
         ReferenceToDIEOffsets[*RefVal].insert(Die.getOffset());
       }
     }
     break;
   }
   case DW_FORM_ref_addr: {
     // Verify all absolute DIE references have valid offsets in the
     // .debug_info section.
     Optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
     assert(RefVal);
     if (RefVal) {
       if (*RefVal >= DCtx.getInfoSection().Data.size()) {
-        ++NumDebugInfoErrors;
+        ++NumUnitErrors;
         OS << "error: DW_FORM_ref_addr offset beyond .debug_info "
               "bounds:\n";
         Die.dump(OS, 0);
         OS << "\n";
       } else {
         // Valid reference, but we will verify it points to an actual
         // DIE later.
         ReferenceToDIEOffsets[*RefVal].insert(Die.getOffset());
       }
     }
     break;
   }
   case DW_FORM_strp: {
     auto SecOffset = AttrValue.Value.getAsSectionOffset();
     assert(SecOffset); // DW_FORM_strp is a section offset.
     if (SecOffset && *SecOffset >= DCtx.getStringSection().size()) {
-      ++NumDebugInfoErrors;
+      ++NumUnitErrors;
       OS << "error: DW_FORM_strp offset beyond .debug_str bounds:\n";
       Die.dump(OS, 0);
       OS << "\n";
     }
     break;
   }
   default:
     break;
   }
 }
 
-void DWARFVerifier::verifyDebugInfoReferences() {
+void DWARFVerifier::verifyDebugInfoReferences(uint32_t &NumDebugInfoErrors) {
   // Take all references and make sure they point to an actual DIE by
   // getting the DIE by offset and emitting an error
   OS << "Verifying .debug_info references...\n";
   for (auto Pair : ReferenceToDIEOffsets) {
     auto Die = DCtx.getDIEForOffset(Pair.first);
     if (Die)
       continue;
     ++NumDebugInfoErrors;
     OS << "error: invalid DIE reference " << format("0x%08" PRIx64, Pair.first)
        << ". Offset is in between DIEs:\n";
     for (auto Offset : Pair.second) {
       auto ReferencingDie = DCtx.getDIEForOffset(Offset);
       ReferencingDie.dump(OS, 0);
       OS << "\n";
     }
     OS << "\n";
   }
 }
 
-bool DWARFVerifier::handleDebugInfo() {
-  NumDebugInfoErrors = 0;
-  OS << "Verifying .debug_info...\n";
-  for (const auto &CU : DCtx.compile_units()) {
-    unsigned NumDies = CU->getNumDIEs();
-    for (unsigned I = 0; I < NumDies; ++I) {
-      auto Die = CU->getDIEAtIndex(I);
-      const auto Tag = Die.getTag();
-      if (Tag == DW_TAG_null)
-        continue;
-      for (auto AttrValue : Die.attributes()) {
-        verifyDebugInfoAttribute(Die, AttrValue);
-        verifyDebugInfoForm(Die, AttrValue);
-      }
-    }
-  }
-  verifyDebugInfoReferences();
-  return NumDebugInfoErrors == 0;
-}
-
 void DWARFVerifier::verifyDebugLineStmtOffsets() {
   std::map<uint64_t, DWARFDie> StmtListToDie;
   for (const auto &CU : DCtx.compile_units()) {
     auto Die = CU->getUnitDIE();
     // Get the attribute value as a section offset. No need to produce an
     // error here if the encoding isn't correct because we validate this in
     // the .debug_info verifier.
     auto StmtSectionOffset = toSectionOffset(Die.find(DW_AT_stmt_list));

test/tools/llvm-dwarfdump/X86/verify_debug_info.s

+# RUN: llvm-mc %s -filetype obj -triple x86_64-apple-darwin -o - \
+# RUN: | not llvm-dwarfdump -verify - \
+# RUN: | FileCheck %s
+
+# CHECK: Verifying .debug_info Unit Header Chain...
+# CHECK-NEXT: error: DIE has invalid DW_AT_stmt_list encoding:{{[[:space:]]}}
+# CHECK-NEXT: 0x0000000c: DW_TAG_compile_unit [1] *
+# CHECK-NEXT: DW_AT_producer [DW_FORM_strp] ( .debug_str[0x00000000] = "clang version 5.0.0 (trunk 308185) (llvm/trunk 308186)")
+# CHECK-NEXT: DW_AT_language [DW_FORM_data2]  (DW_LANG_C99)
+# CHECK-NEXT: DW_AT_name [DW_FORM_strp] ( .debug_str[0x00000037] = "basic.c")
+# CHECK-NEXT: DW_AT_stmt_list [DW_FORM_strx4] ( indexed (00000000) string = )
+# CHECK-NEXT: DW_AT_comp_dir [DW_FORM_strp] ( .debug_str[0x0000003f] = "/Users/sgravani/Development/tests")
+# CHECK-NEXT: DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
+# CHECK-NEXT: DW_AT_high_pc [DW_FORM_data4] (0x00000016){{[[:space:]]}}
+# CHECK-NEXT: Units[2] - start offset: 0x00000068 
+# CHECK-NEXT: Error: The length for this unit is too large for the .debug_info provided.
+# CHECK-NEXT: Error: The unit type encoding is not valid.
+
+
+  .section  __TEXT,__text,regular,pure_instructions
+  .globl  _main                   ## -- Begin function main
+  .p2align  4, 0x90
+_main:                                  ## @main
+Lfunc_begin0:
+  .file 1 "basic.c"
+  .loc  1 1 0                   ## basic.c:1:0
+  .cfi_startproc
+## BB#0:                                ## %entry
+  pushq %rbp
+Lcfi0:
+  .cfi_def_cfa_offset 16
+Lcfi1:
+  .cfi_offset %rbp, -16
+  movq  %rsp, %rbp
+Lcfi2:
+  .cfi_def_cfa_register %rbp
+  xorl  %eax, %eax
+  movl  $0, -4(%rbp)
+Ltmp0:
+  .loc  1 2 7 prologue_end      ## basic.c:2:7
+  movl  $1, -8(%rbp)
+  .loc  1 3 3                   ## basic.c:3:3
+  popq  %rbp
+  retq
+Ltmp1:
+Lfunc_end0:
+  .cfi_endproc
+                                        ## -- End function
+  .section  __DWARF,__debug_str,regular,debug
+Linfo_string:
+  .asciz  "clang version 5.0.0 (trunk 308185) (llvm/trunk 308186)" ## string offset=0
+  .asciz  "basic.c"               ## string offset=55
+  .asciz  "/Users/sgravani/Development/tests" ## string offset=63
+  .asciz  "main"                  ## string offset=97
+  .asciz  "int"                   ## string offset=102
+  .asciz  "a"                     ## string offset=106
+  .section  __DWARF,__debug_abbrev,regular,debug
+Lsection_abbrev:
+  .byte 1                       ## Abbreviation Code
+  .byte 17                      ## DW_TAG_compile_unit
+  .byte 1                       ## DW_CHILDREN_yes
+  .byte 37                      ## DW_AT_producer
+  .byte 14                      ## DW_FORM_strp
+  .byte 19                      ## DW_AT_language
+  .byte 5                       ## DW_FORM_data2
+  .byte 3                       ## DW_AT_name
+  .byte 14                      ## DW_FORM_strp
+  .byte 16                      ## DW_AT_stmt_list
+  .byte 40                      ## DW_FORM_sec_offset -- error: DIE has invalid DW_AT_stmt_list encoding:
+  .byte 27                      ## DW_AT_comp_dir
+  .byte 14                      ## DW_FORM_strp
+  .byte 17                      ## DW_AT_low_pc
+  .byte 1                       ## DW_FORM_addr
+  .byte 18                      ## DW_AT_high_pc
+  .byte 6                       ## DW_FORM_data4
+  .byte 0                       ## EOM(1)
+  .byte 0                       ## EOM(2)
+  .byte 2                       ## Abbreviation Code
+  .byte 46                      ## DW_TAG_subprogram
+  .byte 1                       ## DW_CHILDREN_yes
+  .byte 17                      ## DW_AT_low_pc
+  .byte 1                       ## DW_FORM_addr
+  .byte 18                      ## DW_AT_high_pc
+  .byte 6                       ## DW_FORM_data4
+  .byte 64                      ## DW_AT_frame_base
+  .byte 24                      ## DW_FORM_exprloc
+  .byte 3                       ## DW_AT_name
+  .byte 14                      ## DW_FORM_strp
+  .byte 58                      ## DW_AT_decl_file
+  .byte 11                      ## DW_FORM_data1
+  .byte 59                      ## DW_AT_decl_line
+  .byte 11                      ## DW_FORM_data1
+  .byte 39                      ## DW_AT_prototyped
+  .byte 25                      ## DW_FORM_flag_present
+  .byte 73                      ## DW_AT_type
+  .byte 19                      ## DW_FORM_ref4
+  .byte 63                      ## DW_AT_external
+  .byte 25                      ## DW_FORM_flag_present
+  .byte 0                       ## EOM(1)
+  .byte 0                       ## EOM(2)
+  .byte 3                       ## Abbreviation Code
+  .byte 52                      ## DW_TAG_variable
+  .byte 0                       ## DW_CHILDREN_no
+  .byte 2                       ## DW_AT_location
+  .byte 24                      ## DW_FORM_exprloc
+  .byte 3                       ## DW_AT_name
+  .byte 14                      ## DW_FORM_strp
+  .byte 58                      ## DW_AT_decl_file
+  .byte 11                      ## DW_FORM_data1
+  .byte 59                      ## DW_AT_decl_line
+  .byte 11                      ## DW_FORM_data1
+  .byte 73                      ## DW_AT_type
+  .byte 19                      ## DW_FORM_ref4
+  .byte 0                       ## EOM(1)
+  .byte 0                       ## EOM(2)
+  .byte 4                       ## Abbreviation Code
+  .byte 36                      ## DW_TAG_base_type
+  .byte 0                       ## DW_CHILDREN_no
+  .byte 3                       ## DW_AT_name
+  .byte 14                      ## DW_FORM_strp
+  .byte 62                      ## DW_AT_encoding
+  .byte 11                      ## DW_FORM_data1
+  .byte 11                      ## DW_AT_byte_size
+  .byte 11                      ## DW_FORM_data1
+  .byte 0                       ## EOM(1)
+  .byte 0                       ## EOM(2)
+  .byte 0                       ## EOM(3)
+  .section  __DWARF,__debug_info,regular,debug
+Lsection_info:
+Lcu_begin0:
+  .long 87                      ## Length of Unit
+  .short  5                       ## DWARF version number
+  .byte 1                       ## DWARF Unit Type
+  .byte 8                       ## Address Size (in bytes)
+Lset0 = Lsection_abbrev-Lsection_abbrev ## Offset Into Abbrev. Section
+  .long Lset0
+  .byte 1                       ## Abbrev [1] 0xc:0x4f DW_TAG_compile_unit
+  .long 0                       ## DW_AT_producer
+  .short  12                      ## DW_AT_language
+  .long 55                      ## DW_AT_name
+Lset1 = Lline_table_start0-Lsection_line ## DW_AT_stmt_list
+  .long Lset1
+  .long 63                      ## DW_AT_comp_dir
+  .quad Lfunc_begin0            ## DW_AT_low_pc
+Lset2 = Lfunc_end0-Lfunc_begin0         ## DW_AT_high_pc
+  .long Lset2
+  .byte 2                       ## Abbrev [2] 0x2b:0x28 DW_TAG_subprogram
+  .quad Lfunc_begin0            ## DW_AT_low_pc
+Lset3 = Lfunc_end0-Lfunc_begin0         ## DW_AT_high_pc
+  .long Lset3
+  .byte 1                       ## DW_AT_frame_base
+  .byte 86
+  .long 97                      ## DW_AT_name
+  .byte 1                       ## DW_AT_decl_file
+  .byte 1                       ## DW_AT_decl_line
+                                        ## DW_AT_prototyped
+  .long 83                      ## DW_AT_type
+                                        ## DW_AT_external
+  .byte 3                       ## Abbrev [3] 0x44:0xe DW_TAG_variable
+  .byte 2                       ## DW_AT_location
+  .byte 145
+  .byte 120
+  .long 106                     ## DW_AT_name
+  .byte 1                       ## DW_AT_decl_file
+  .byte 2                       ## DW_AT_decl_line
+  .long 83                      ## DW_AT_type
+  .byte 0                       ## End Of Children Mark
+  .byte 4                       ## Abbrev [4] 0x53:0x7 DW_TAG_base_type
+  .long 102                     ## DW_AT_name
+  .byte 5                       ## DW_AT_encoding
+  .byte 4                       ## DW_AT_byte_size
+  .byte 0                       ## End Of Children Mark
+Lcu_begin1:
+  .long 9                      ## Length of Unit
+  .short  5                       ## DWARF version number
+  .byte 1                       ## DWARF Unit Type
+  .byte 4                       ## Address Size (in bytes)
+  .long 0           ## Abbrev offset
+  .byte   0 
+Ltu_begin0:
+  .long 26                      ## Length of Unit -- Error: The length for this unit is too large for the .debug_info provided.
+  .short  5                       ## DWARF version number
+  .byte 0                       ## DWARF Unit Type
+  .byte 4                       ## Address Size (in bytes)
+  .long 0
+  .quad 0
+  .long   0
+  .byte   0     
+
+.subsections_via_symbols
+  .section  __DWARF,__debug_line,regular,debug
+Lsection_line:
+Lline_table_start0: