[lldb] Add the ability to load DWARF64 .debug_str_offsets tables for DWARF32 DWARF units in .dwp files in LLDB. #167997
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@llvm/pr-subscribers-lldb Author: Greg Clayton (clayborg) ChangesThis patch is updating the reading capabilities of the LLDB DWARF parser for a llvm-dwp patch #167457 that will emit .dwp files where the compile units are DWARF32 and the .debug_str_offsets tables will be emitted as DWARF64 to allow .debug_str sections that exceed 4GB in size. Full diff: https://github.com/llvm/llvm-project/pull/167997.diff 5 Files Affected:
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
index 94fc2e83e899d..14bfa75d772a4 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -360,8 +360,10 @@ void DWARFUnit::SetDwoStrOffsetsBase() {
const DWARFDataExtractor &strOffsets =
GetSymbolFileDWARF().GetDWARFContext().getOrLoadStrOffsetsData();
uint64_t length = strOffsets.GetU32(&baseOffset);
- if (length == 0xffffffff)
+ if (length == llvm::dwarf::DW_LENGTH_DWARF64) {
length = strOffsets.GetU64(&baseOffset);
+ m_str_offsets_size = 8;
+ }
// Check version.
if (strOffsets.GetU16(&baseOffset) < 5)
@@ -369,8 +371,13 @@ void DWARFUnit::SetDwoStrOffsetsBase() {
// Skip padding.
baseOffset += 2;
+ } else {
+ // Size of offset for .debug_str_offsets is same as DWARF offset byte size
+ // of the DWARFUnit for DWARF version 4 and earlier.
+ m_str_offsets_size = m_header.getDwarfOffsetByteSize();
}
+
SetStrOffsetsBase(baseOffset);
}
@@ -1079,10 +1086,9 @@ uint32_t DWARFUnit::GetHeaderByteSize() const { return m_header.getSize(); }
std::optional<uint64_t>
DWARFUnit::GetStringOffsetSectionItem(uint32_t index) const {
- lldb::offset_t offset =
- GetStrOffsetsBase() + index * m_header.getDwarfOffsetByteSize();
+ lldb::offset_t offset = GetStrOffsetsBase() + index * m_str_offsets_size;
return m_dwarf.GetDWARFContext().getOrLoadStrOffsetsData().GetMaxU64(
- &offset, m_header.getDwarfOffsetByteSize());
+ &offset, m_str_offsets_size);
}
llvm::Expected<llvm::DWARFAddressRangesVector>
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
index 91a693860c55a..fa863eb8417ab 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
@@ -364,6 +364,7 @@ class DWARFUnit : public DWARFExpression::Delegate, public UserID {
dw_offset_t m_line_table_offset = DW_INVALID_OFFSET;
dw_offset_t m_str_offsets_base = 0; // Value of DW_AT_str_offsets_base.
+ dw_offset_t m_str_offsets_size = 4; // Size in bytes of the string offsets.
std::optional<llvm::DWARFDebugRnglistTable> m_rnglist_table;
bool m_rnglist_table_done = false;
diff --git a/lldb/test/Shell/SymbolFile/DWARF/Inputs/dwp-str-offsets-dwarf64-dwp.yaml b/lldb/test/Shell/SymbolFile/DWARF/Inputs/dwp-str-offsets-dwarf64-dwp.yaml
new file mode 100644
index 0000000000000..d4e2ceea9c4f6
--- /dev/null
+++ b/lldb/test/Shell/SymbolFile/DWARF/Inputs/dwp-str-offsets-dwarf64-dwp.yaml
@@ -0,0 +1,44 @@
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_REL
+ Machine: EM_X86_64
+ SectionHeaderStringTable: .strtab
+Sections:
+ - Name: .debug_abbrev.dwo
+ Type: SHT_PROGBITS
+ Flags: [ SHF_EXCLUDE ]
+ AddressAlign: 0x1
+ Content: 01110125251305032576250000022E01111B1206401803253A0B3B0B49133F190000030500021803253A0B3B0B4913000004240003253E0B0B0B0000050F00491300000626004913000000
+ - Name: .debug_str.dwo
+ Type: SHT_PROGBITS
+ Flags: [ SHF_EXCLUDE, SHF_MERGE, SHF_STRINGS ]
+ AddressAlign: 0x1
+ EntSize: 0x1
+ Content: 6D61696E00696E74006172676300617267760063686172004170706C6520636C616E672076657273696F6E2031372E302E302028636C616E672D313730302E342E342E3129006D61696E2E6D696E696D616C2E637070006D61696E2E6D696E696D616C2E64776F00
+ - Name: .debug_str_offsets.dwo
+ Type: SHT_PROGBITS
+ Flags: [ SHF_EXCLUDE ]
+ AddressAlign: 0x1
+ Content: 'FFFFFFFF4400000000000000050000000000000000000000050000000000000009000000000000000E000000000000001300000000000000180000000000000046000000000000005700000000000000'
+ - Name: .debug_info.dwo
+ Type: SHT_PROGBITS
+ Flags: [ SHF_EXCLUDE ]
+ AddressAlign: 0x1
+ Content: 54000000050005080000000099E97383BBC6980B0105210006070200160000000156000001400000000302917802000140000000030291700300014400000000040105040549000000054E00000006530000000404060100
+ - Name: .debug_cu_index
+ Type: SHT_PROGBITS
+ AddressAlign: 0x1
+ Content: 05000000030000000100000002000000000000000000000099E97383BBC6980B0000000001000000010000000300000006000000000000000000000000000000580000004B00000028000000
+ - Type: SectionHeaderTable
+ Sections:
+ - Name: .strtab
+ - Name: .debug_abbrev.dwo
+ - Name: .debug_str.dwo
+ - Name: .debug_str_offsets.dwo
+ - Name: .debug_info.dwo
+ - Name: .debug_cu_index
+ - Name: .symtab
+Symbols: []
+...
diff --git a/lldb/test/Shell/SymbolFile/DWARF/Inputs/dwp-str-offsets-dwarf64-exe.yaml b/lldb/test/Shell/SymbolFile/DWARF/Inputs/dwp-str-offsets-dwarf64-exe.yaml
new file mode 100644
index 0000000000000..3785bbe6ecbe0
--- /dev/null
+++ b/lldb/test/Shell/SymbolFile/DWARF/Inputs/dwp-str-offsets-dwarf64-exe.yaml
@@ -0,0 +1,100 @@
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+ProgramHeaders:
+ - Type: PT_PHDR
+ Flags: [ PF_R ]
+ VAddr: 0x200040
+ Align: 0x8
+ Offset: 0x40
+ - Type: PT_LOAD
+ Flags: [ PF_R ]
+ FirstSec: .eh_frame
+ LastSec: .eh_frame
+ VAddr: 0x200000
+ Align: 0x1000
+ Offset: 0x0
+ - Type: PT_LOAD
+ Flags: [ PF_X, PF_R ]
+ FirstSec: .text
+ LastSec: .text
+ VAddr: 0x201160
+ Align: 0x1000
+ Offset: 0x160
+ - Type: PT_GNU_STACK
+ Flags: [ PF_W, PF_R ]
+ Align: 0x0
+ Offset: 0x0
+Sections:
+ - Name: .eh_frame
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC ]
+ Address: 0x200120
+ AddressAlign: 0x8
+ Content: 1400000000000000017A5200017810011B0C0708900100001C0000001C000000201000001600000000410E108602430D06510C070800000000000000
+ - Name: .text
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ Address: 0x201160
+ AddressAlign: 0x10
+ Content: 554889E5C745FC00000000897DF8488975F031C05DC3
+ - Name: .debug_abbrev
+ Type: SHT_PROGBITS
+ AddressAlign: 0x1
+ Content: 014A00101772171B25B442197625111B12067317000000
+ - Name: .debug_info
+ Type: SHT_PROGBITS
+ AddressAlign: 0x1
+ Content: 24000000050004080000000099E97383BBC6980B0100000000080000000001001600000008000000
+ - Name: .debug_str_offsets
+ Type: SHT_PROGBITS
+ AddressAlign: 0x1
+ Content: 0C000000050000000000000002000000
+ - Name: .debug_gnu_pubnames
+ Type: SHT_PROGBITS
+ AddressAlign: 0x1
+ Content: 18000000020000000000280000001A000000306D61696E0000000000
+ - Name: .debug_gnu_pubtypes
+ Type: SHT_PROGBITS
+ AddressAlign: 0x1
+ Content: '21000000020000000000280000004000000090696E74005300000090636861720000000000'
+ - Name: .comment
+ Type: SHT_PROGBITS
+ Flags: [ SHF_MERGE, SHF_STRINGS ]
+ AddressAlign: 0x1
+ EntSize: 0x1
+ Content: 004170706C6520636C616E672076657273696F6E2031372E302E302028636C616E672D313730302E342E342E3129004C696E6B65723A204C4C442032322E302E30202868747470733A2F2F6769746875622E636F6D2F636C6179626F72672F6C6C766D2D70726F6A6563742E67697420613234333130363863303837656463303938393330303934343864343162356138336361303363392900
+ - Name: .debug_line
+ Type: SHT_PROGBITS
+ AddressAlign: 0x1
+ Content: 5A0000000500080037000000010101FB0E0D00010101010000000100000101011F010000000003011F020F051E0102000000004E0649A10A56ED4D381C49A3DB4F6825040000090260112000000000000105030A0821060B2E0202000101
+ - Name: .debug_line_str
+ Type: SHT_PROGBITS
+ Flags: [ SHF_MERGE, SHF_STRINGS ]
+ AddressAlign: 0x1
+ EntSize: 0x1
+ Content: 2E006D61696E2E6D696E696D616C2E63707000
+Symbols:
+ - Name: main.minimal.cpp
+ Type: STT_FILE
+ Index: SHN_ABS
+ - Name: main
+ Type: STT_FUNC
+ Section: .text
+ Binding: STB_GLOBAL
+ Value: 0x201160
+ Size: 0x16
+DWARF:
+ debug_str:
+ - .
+ - main.minimal.dwo
+ debug_addr:
+ - Length: 0xC
+ Version: 0x5
+ AddressSize: 0x8
+ Entries:
+ - Address: 0x201160
+...
diff --git a/lldb/test/Shell/SymbolFile/DWARF/dwp-str-offsets-dwarf64.test b/lldb/test/Shell/SymbolFile/DWARF/dwp-str-offsets-dwarf64.test
new file mode 100644
index 0000000000000..b010aa0995971
--- /dev/null
+++ b/lldb/test/Shell/SymbolFile/DWARF/dwp-str-offsets-dwarf64.test
@@ -0,0 +1,25 @@
+# This test verifies that LLDB can read a .dwp file that has a DWARF32 compile
+# unit that has a DWARF64 .debug_str_offsets table. This will be needed for
+# llvm-dwp changes that will start emitting 64 bit line tables for compile units
+# that have strings in the .debug_str section whose string offsets exceed 4GB.
+# By having a 64 bit .debug_str_offsets table, we can emit .debug_str sections
+# with no size limits.
+
+# RUN: yaml2obj %S/Inputs/dwp-str-offsets-dwarf64-exe.yaml > %t
+# RUN: yaml2obj %S/Inputs/dwp-str-offsets-dwarf64-dwp.yaml > %t.dwp
+# RUN: %lldb %t -b \
+# RUN: -o 'image lookup --verbose --address 0x0000000000201172' | \
+# RUN: FileCheck %s
+
+# CHECK: (lldb) image lookup --verbose --address 0x0000000000201172
+# CHECK-NEXT: Address: dwp-str-offsets-dwarf64.test.tmp[0x0000000000201172] (dwp-str-offsets-dwarf64.test.tmp.PT_LOAD[1]..text + 18)
+# CHECK-NEXT: Summary: dwp-str-offsets-dwarf64.test.tmp`main + 18 at main.minimal.cpp:2:3
+# CHECK-NEXT: Module: file = "{{.*}}/dwp-str-offsets-dwarf64.test.tmp", arch = "x86_64"
+# CHECK-NEXT: CompileUnit: id = {0x00000000}, file = "main.minimal.cpp", language = "<not loaded>"
+# CHECK-NEXT: Function: id = {0x7fffff000000001a}, name = "main", range = [0x0000000000201160-0x0000000000201176)
+# CHECK-NEXT: FuncType: id = {0x7fffff000000001a}, byte-size = 0, decl = main.minimal.cpp:1, compiler_type = "int (int, const char **)"
+# CHECK-NEXT: Blocks: id = {0x7fffff000000001a}, range = [0x00201160-0x00201176)
+# CHECK-NEXT: LineEntry: [0x0000000000201172-0x0000000000201174): main.minimal.cpp:2:3
+# CHECK-NEXT: Symbol: id = {0x00000002}, range = [0x0000000000201160-0x0000000000201176), name="main"
+# CHECK-NEXT: Variable: id = {0x7fffff0000000029}, name = "argc", type = "int", valid ranges = <block>, location = DW_OP_fbreg -8, decl = main.minimal.cpp:1
+# CHECK-NEXT: Variable: id = {0x7fffff0000000034}, name = "argv", type = "const char **", valid ranges = <block>, location = DW_OP_fbreg -16, decl = main.minimal.cpp:1
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✅ With the latest revision this PR passed the C/C++ code formatter. |
Michael137
approved these changes
Nov 14, 2025
Collaborator
Author
I fixed the unit test failure and refactored a bit. |
dwblaikie
reviewed
Nov 14, 2025
Comment on lines
366
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| uint64_t length = strOffsets.GetU32(&baseOffset); | ||
| if (length == 0xffffffff) | ||
| if (length == llvm::dwarf::DW_LENGTH_DWARF64) { | ||
| length = strOffsets.GetU64(&baseOffset); | ||
| m_str_offset_size = 8; | ||
| } |
Collaborator
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Do we have a utility for reading the 32/64 encoded length we could reuse here?
Collaborator
Author
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We don't. The LLVM one is hidden and not in the DWARFDataExtractor and there is no counterpart in LLDB's DWARFDataExtractor.
Collaborator
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I was able to use the LLVM DWARFDataExtractor and re-use the getInitialLength() function from there.
Comment on lines
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| } | ||
|
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||
| SetStrOffsetsBase(baseOffset); |
Collaborator
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Remove unrelated reformatting
…DWARF32 DWARF units in .dwp files in LLDB. This patch is updating the reading capabilities of the LLDB DWARF parser for a llvm-dwp patch llvm#167457 that will emit .dwp files where the compile units are DWARF32 and the .debug_str_offsets tables will be emitted as DWARF64 to allow .debug_str sections that exceed 4GB in size.
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dwblaikie
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Nov 15, 2025
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| uint64_t length; | ||
| llvm::dwarf::DwarfFormat format; | ||
| std::tie(length, format) = strOffsets.getInitialLength(&baseOffset); |
Collaborator
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Might be simpler to write that as auto [length, format] = strOffsets... (though it is a readability tradeoff due to omitting the types of the two variables)
Contributor
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The buildbots lldb-x86_64-win and lldb-remote-linux-win are broken after this patch. |
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This patch is updating the reading capabilities of the LLDB DWARF parser for a llvm-dwp patch #167457 that will emit .dwp files where the compile units are DWARF32 and the .debug_str_offsets tables will be emitted as DWARF64 to allow .debug_str sections that exceed 4GB in size.