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DWARFVerifier: Verify CU/TU index overlap issues
Discovered in a large object that would need a 64 bit index (but the cu/tu index format doesn't include a 64 bit offset/length mode in DWARF64 - a spec bug) but instead binutils dwp overflowed the offsets causing overlapping regions.
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‎llvm/include/llvm/DebugInfo/DWARF/DWARFUnitIndex.h

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Original file line numberDiff line numberDiff line change
@@ -64,6 +64,25 @@ enum DWARFSectionKind {
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DW_SECT_EXT_MACINFO = 10,
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};
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inline const char *toString(DWARFSectionKind Kind) {
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switch (Kind) {
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case DW_SECT_EXT_unknown:
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return "Unknown DW_SECT value 0";
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#define STRINGIZE(X) #X
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#define HANDLE_DW_SECT(ID, NAME) \
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case DW_SECT_##NAME: \
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return "DW_SECT_" STRINGIZE(NAME);
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#include "llvm/BinaryFormat/Dwarf.def"
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case DW_SECT_EXT_TYPES:
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return "DW_SECT_TYPES";
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case DW_SECT_EXT_LOC:
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return "DW_SECT_LOC";
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case DW_SECT_EXT_MACINFO:
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return "DW_SECT_MACINFO";
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}
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llvm_unreachable("unknown DWARFSectionKind");
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}
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/// Convert the internal value for a section kind to an on-disk value.
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///
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/// The conversion depends on the version of the index section.

‎llvm/include/llvm/DebugInfo/DWARF/DWARFVerifier.h

Lines changed: 23 additions & 0 deletions
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@@ -14,6 +14,7 @@
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#include "llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h"
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#include "llvm/DebugInfo/DWARF/DWARFAddressRange.h"
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#include "llvm/DebugInfo/DWARF/DWARFDie.h"
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#include "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
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#include <cstdint>
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#include <map>
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#include <set>
@@ -156,6 +157,10 @@ class DWARFVerifier {
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unsigned verifyUnitSection(const DWARFSection &S);
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unsigned verifyUnits(const DWARFUnitVector &Units);
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unsigned verifyIndexes(const DWARFObject &DObj);
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unsigned verifyIndex(StringRef Name, DWARFSectionKind SectionKind,
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StringRef Index);
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/// Verifies that a call site entry is nested within a subprogram with a
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/// DW_AT_call attribute.
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///
@@ -300,6 +305,24 @@ class DWARFVerifier {
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/// \returns true if all sections verify successfully, false otherwise.
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bool handleDebugInfo();
302307

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/// Verify the information in the .debug_cu_index section.
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///
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/// Any errors are reported to the stream that was this object was
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/// constructed with.
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///
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/// \returns true if the .debug_cu_index verifies successfully, false
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/// otherwise.
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bool handleDebugCUIndex();
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/// Verify the information in the .debug_tu_index section.
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///
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/// Any errors are reported to the stream that was this object was
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/// constructed with.
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///
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/// \returns true if the .debug_tu_index verifies successfully, false
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/// otherwise.
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bool handleDebugTUIndex();
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/// Verify the information in the .debug_line section.
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///
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/// Any errors are reported to the stream that was this object was

‎llvm/lib/DebugInfo/DWARF/DWARFContext.cpp

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -769,6 +769,10 @@ bool DWARFContext::verify(raw_ostream &OS, DIDumpOptions DumpOpts) {
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DWARFVerifier verifier(OS, *this, DumpOpts);
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Success &= verifier.handleDebugAbbrev();
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if (DumpOpts.DumpType & DIDT_DebugCUIndex)
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Success &= verifier.handleDebugCUIndex();
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if (DumpOpts.DumpType & DIDT_DebugTUIndex)
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Success &= verifier.handleDebugTUIndex();
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if (DumpOpts.DumpType & DIDT_DebugInfo)
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Success &= verifier.handleDebugInfo();
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if (DumpOpts.DumpType & DIDT_DebugLine)

‎llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp

Lines changed: 52 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/DebugInfo/DWARF/DWARFVerifier.h"
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#include "llvm/ADT/IntervalMap.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/BinaryFormat/Dwarf.h"
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#include "llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h"
@@ -395,6 +396,57 @@ unsigned DWARFVerifier::verifyUnitSection(const DWARFSection &S) {
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return NumDebugInfoErrors;
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}
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unsigned DWARFVerifier::verifyIndex(StringRef Name,
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DWARFSectionKind InfoColumnKind,
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StringRef IndexStr) {
402+
if (IndexStr.empty())
403+
return 0;
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OS << "Verifying " << Name << "...\n";
405+
DWARFUnitIndex Index(InfoColumnKind);
406+
DataExtractor D(IndexStr, DCtx.isLittleEndian(), 0);
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if (!Index.parse(D))
408+
return 1;
409+
IntervalMap<uint32_t, uint64_t>::Allocator Alloc;
410+
std::vector<IntervalMap<uint32_t, uint64_t>> Sections(
411+
Index.getColumnKinds().size(), IntervalMap<uint32_t, uint64_t>(Alloc));
412+
for (const DWARFUnitIndex::Entry &E : Index.getRows()) {
413+
uint64_t Sig = E.getSignature();
414+
if (!E.getContributions())
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continue;
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for (auto E : enumerate(InfoColumnKind == DW_SECT_INFO
417+
? makeArrayRef(E.getContributions(),
418+
Index.getColumnKinds().size())
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: makeArrayRef(E.getContribution(), 1))) {
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const DWARFUnitIndex::Entry::SectionContribution &SC = E.value();
421+
int Col = E.index();
422+
if (SC.Length == 0)
423+
continue;
424+
auto &M = Sections[Col];
425+
auto I = M.find(SC.Offset);
426+
if (I != M.end() && I.start() < (SC.Offset + SC.Length)) {
427+
error() << llvm::formatv(
428+
"overlapping index entries for entries {0:x16} "
429+
"and {1:x16} for column {2}\n",
430+
*I, Sig, toString(Index.getColumnKinds()[Col]));
431+
return 1;
432+
}
433+
M.insert(SC.Offset, SC.Offset + SC.Length - 1, Sig);
434+
}
435+
}
436+
437+
return 0;
438+
}
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440+
bool DWARFVerifier::handleDebugCUIndex() {
441+
return verifyIndex(".debug_cu_index", DWARFSectionKind::DW_SECT_INFO,
442+
DCtx.getDWARFObj().getCUIndexSection()) == 0;
443+
}
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445+
bool DWARFVerifier::handleDebugTUIndex() {
446+
return verifyIndex(".debug_tu_index", DWARFSectionKind::DW_SECT_EXT_TYPES,
447+
DCtx.getDWARFObj().getTUIndexSection()) == 0;
448+
}
449+
398450
bool DWARFVerifier::handleDebugInfo() {
399451
const DWARFObject &DObj = DCtx.getDWARFObj();
400452
unsigned NumErrors = 0;

‎llvm/test/DebugInfo/X86/debug-cu-index-overlap.s

Lines changed: 100 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,100 @@
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# RUN: llvm-mc -triple x86_64-unknown-linux %s -filetype=obj -o - | \
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# RUN: not llvm-dwarfdump -debug-cu-index -debug-tu-index --verify - | FileCheck %s
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4+
# FIXME: The verifier should probably be handled to verify the hash table
5+
# itself - in which case this test would need to be updated to have a correct
6+
# hash table (currently hand crafted with no attempt at correct allocation of
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# hashes to buckets) - and probably to verify that the section ranges apply to
8+
# sections that exist, which currently they don't
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10+
# This tests that an index that describes units as being in overlapping
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# sections is invalid (this was observed in the wild due to overflow due to the
12+
# 32 bit limit of the indexes (a DWARF spec bug - there should be a 64 bit
13+
# version of the index format with 64 bit offsets/sizes)) - but Type Units will
14+
# generally share all the sections other than the info section with each other
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# (and with their originating CU) since the dwo format has no way to describe
16+
# which part of non-info-section contributions are used by which units, so
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# they're all shared. So demonstrate that the TU index ignores non-info overlap,
18+
# but the CU index diagnoses such overlap (in the abbrev section, in this case)
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20+
# This doesn't currently check for info section overlap between the CU and TU
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# index, but that could be an extension of this work in the future.
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# CHECK: Verifying .debug_cu_index...
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# CHECK: error: overlapping index entries for entries 0x0000000000000001 and 0x0000000000000002 for column DW_SECT_ABBREV
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# CHECK: Verifying .debug_tu_index...
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# CHECK: error: overlapping index entries for entries 0x0000000000000001 and 0x0000000000000003 for column DW_SECT_INFO
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.section .debug_cu_index, "", @progbits
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## Header:
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.long 5 # Version
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.long 2 # Section count
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.long 3 # Unit count
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.long 4 # Slot count
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## Hash Table of Signatures:
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.quad 0x0000000000000001
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.quad 0x0000000000000002
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.quad 0x0000000000000003
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.quad 0
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## Parallel Table of Indexes:
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.long 1
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.long 2
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.long 3
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.long 0
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## Table of Section Offsets:
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## Row 0:
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.long 1 # DW_SECT_INFO
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.long 3 # DW_SECT_ABBREV
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## Row 1:
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.long 0x1 # Offset in .debug_info.dwo
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.long 0x1 # Offset in .debug_abbrev.dwo
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## Row 2:
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.long 0x2 # Offset in .debug_info.dwo
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.long 0x1 # Offset in .debug_abbrev.dwo
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## Row 3:
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.long 0x1 # Offset in .debug_info.dwo
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.long 0x1 # Offset in .debug_abbrev.dwo
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## Table of Section Sizes:
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.long 0x1 # Size in .debug_info.dwo
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.long 0x1 # Size in .debug_abbrev.dwo
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.long 0x1 # Size in .debug_info.dwo
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.long 0x1 # Size in .debug_abbrev.dwo
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.long 0x1 # Size in .debug_info.dwo
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.long 0x1 # Size in .debug_abbrev.dwo
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65+
.section .debug_tu_index, "", @progbits
66+
## Header:
67+
.long 5 # Version
68+
.long 2 # Section count
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.long 3 # Unit count
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.long 4 # Slot count
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## Hash Table of Signatures:
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.quad 0x0000000000000001
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.quad 0x0000000000000002
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.quad 0x0000000000000003
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.quad 0
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## Parallel Table of Indexes:
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.long 1
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.long 2
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.long 3
80+
.long 0
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## Table of Section Offsets:
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## Row 0:
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.long 1 # DW_SECT_INFO
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.long 3 # DW_SECT_ABBREV
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## Row 1:
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.long 0x1 # Offset in .debug_info.dwo
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.long 0x1 # Offset in .debug_abbrev.dwo
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## Row 2:
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.long 0x2 # Offset in .debug_info.dwo
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.long 0x1 # Offset in .debug_abbrev.dwo
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## Row 3:
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.long 0x1 # Offset in .debug_info.dwo
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.long 0x1 # Offset in .debug_abbrev.dwo
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## Table of Section Sizes:
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.long 0x1 # Size in .debug_info.dwo
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.long 0x1 # Size in .debug_abbrev.dwo
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.long 0x1 # Size in .debug_info.dwo
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.long 0x1 # Size in .debug_abbrev.dwo
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.long 0x1 # Size in .debug_info.dwo
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.long 0x1 # Size in .debug_abbrev.dwo

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