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[BOLT] Fix DWARF4/5 file index handling in debug info functions (#151401)
Fix incorrect file index handling that differed between DWARF4 and DWARF5. DWARF4 file indices start at 1, while DWARF5 starts at 0. The code was manually adjusting indices with `Row.File - 1`, which works for DWARF4 but breaks DWARF5. Replace manual indexing with `getFileNameEntry()` which abstracts away the DWARF version differences. Fixed in: - printDebugInfo() - addDebugFilenameToUnit()
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3 files changed

+406
-11
lines changed

3 files changed

+406
-11
lines changed

‎bolt/lib/Core/BinaryContext.cpp‎

Lines changed: 7 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -1568,23 +1568,19 @@ unsigned BinaryContext::addDebugFilenameToUnit(const uint32_t DestCUID,
15681568
DWARFCompileUnit *SrcUnit = DwCtx->getCompileUnitForOffset(SrcCUID);
15691569
const DWARFDebugLine::LineTable *LineTable =
15701570
DwCtx->getLineTableForUnit(SrcUnit);
1571-
const std::vector<DWARFDebugLine::FileNameEntry> &FileNames =
1572-
LineTable->Prologue.FileNames;
1573-
// Dir indexes start at 1, as DWARF file numbers, and a dir index 0
1571+
const DWARFDebugLine::FileNameEntry &FileNameEntry =
1572+
LineTable->Prologue.getFileNameEntry(FileIndex);
1573+
// Dir indexes start at 1 and a dir index 0
15741574
// means empty dir.
1575-
assert(FileIndex > 0 && FileIndex <= FileNames.size() &&
1576-
"FileIndex out of range for the compilation unit.");
15771575
StringRef Dir = "";
1578-
if (FileNames[FileIndex - 1].DirIdx != 0) {
1576+
if (FileNameEntry.DirIdx != 0) {
15791577
if (std::optional<const char *> DirName = dwarf::toString(
1580-
LineTable->Prologue
1581-
.IncludeDirectories[FileNames[FileIndex - 1].DirIdx - 1])) {
1578+
LineTable->Prologue.IncludeDirectories[FileNameEntry.DirIdx - 1])) {
15821579
Dir = *DirName;
15831580
}
15841581
}
15851582
StringRef FileName = "";
1586-
if (std::optional<const char *> FName =
1587-
dwarf::toString(FileNames[FileIndex - 1].Name))
1583+
if (std::optional<const char *> FName = dwarf::toString(FileNameEntry.Name))
15881584
FileName = *FName;
15891585
assert(FileName != "");
15901586
DWARFCompileUnit *DstUnit = DwCtx->getCompileUnitForOffset(DestCUID);
@@ -1925,7 +1921,7 @@ static void printDebugInfo(raw_ostream &OS, const MCInst &Instruction,
19251921
const DWARFDebugLine::Row &Row = LineTable->Rows[RowRef.RowIndex - 1];
19261922
StringRef FileName = "";
19271923
if (std::optional<const char *> FName =
1928-
dwarf::toString(LineTable->Prologue.FileNames[Row.File - 1].Name))
1924+
dwarf::toString(LineTable->Prologue.getFileNameEntry(Row.File).Name))
19291925
FileName = *FName;
19301926
OS << " # debug line " << FileName << ":" << Row.Line;
19311927
if (Row.Column)

‎bolt/test/X86/dwarf5-debug-line-print.s‎

Lines changed: 148 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,148 @@
1+
# REQUIRES: system-linux
2+
3+
## Check that BOLT correctly prints debug line comments for DWARF-5.
4+
5+
6+
# RUN: llvm-mc -dwarf-version=5 -filetype=obj -triple x86_64-unknown-linux %s -o %t1.o
7+
# RUN: %clang %cflags -dwarf-5 %t1.o -o %t.exe -Wl,-q
8+
# RUN: llvm-bolt %t.exe --update-debug-sections --print-debug-info \
9+
# RUN: --print-after-lowering -o %t.bolt | FileCheck %s
10+
11+
# CHECK: xorq %rdi, %rdi # debug line main.c:2:5
12+
13+
# __attribute__((naked)) void _start() {
14+
# __asm__(
15+
# "xor %rdi, %rdi\n" // exit code 0
16+
# "mov $60, %rax\n" // syscall number for exit
17+
# "syscall\n"
18+
# );
19+
# }
20+
21+
.file "main.c"
22+
.text
23+
.globl _start # -- Begin function _start
24+
.p2align 4
25+
.type _start,@function
26+
_start: # @_start
27+
.Lfunc_begin0:
28+
.file 0 "/home/gpastukhov/tmp2" "main.c" md5 0x94c0e54a615c2a21415ddb904991abd8
29+
.cfi_startproc
30+
# %bb.0:
31+
.loc 0 2 5 prologue_end # main.c:2:5
32+
#APP
33+
xorq %rdi, %rdi
34+
movq $60, %rax
35+
syscall
36+
37+
#NO_APP
38+
.Ltmp0:
39+
.Lfunc_end0:
40+
.size _start, .Lfunc_end0-_start
41+
.cfi_endproc
42+
# -- End function
43+
.section .debug_abbrev,"",@progbits
44+
.byte 1 # Abbreviation Code
45+
.byte 17 # DW_TAG_compile_unit
46+
.byte 1 # DW_CHILDREN_yes
47+
.byte 37 # DW_AT_producer
48+
.byte 37 # DW_FORM_strx1
49+
.byte 19 # DW_AT_language
50+
.byte 5 # DW_FORM_data2
51+
.byte 3 # DW_AT_name
52+
.byte 37 # DW_FORM_strx1
53+
.byte 114 # DW_AT_str_offsets_base
54+
.byte 23 # DW_FORM_sec_offset
55+
.byte 16 # DW_AT_stmt_list
56+
.byte 23 # DW_FORM_sec_offset
57+
.byte 27 # DW_AT_comp_dir
58+
.byte 37 # DW_FORM_strx1
59+
.byte 17 # DW_AT_low_pc
60+
.byte 27 # DW_FORM_addrx
61+
.byte 18 # DW_AT_high_pc
62+
.byte 6 # DW_FORM_data4
63+
.byte 115 # DW_AT_addr_base
64+
.byte 23 # DW_FORM_sec_offset
65+
.byte 0 # EOM(1)
66+
.byte 0 # EOM(2)
67+
.byte 2 # Abbreviation Code
68+
.byte 46 # DW_TAG_subprogram
69+
.byte 0 # DW_CHILDREN_no
70+
.byte 17 # DW_AT_low_pc
71+
.byte 27 # DW_FORM_addrx
72+
.byte 18 # DW_AT_high_pc
73+
.byte 6 # DW_FORM_data4
74+
.byte 64 # DW_AT_frame_base
75+
.byte 24 # DW_FORM_exprloc
76+
.byte 3 # DW_AT_name
77+
.byte 37 # DW_FORM_strx1
78+
.byte 58 # DW_AT_decl_file
79+
.byte 11 # DW_FORM_data1
80+
.byte 59 # DW_AT_decl_line
81+
.byte 11 # DW_FORM_data1
82+
.byte 63 # DW_AT_external
83+
.byte 25 # DW_FORM_flag_present
84+
.byte 0 # EOM(1)
85+
.byte 0 # EOM(2)
86+
.byte 0 # EOM(3)
87+
.section .debug_info,"",@progbits
88+
.Lcu_begin0:
89+
.long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
90+
.Ldebug_info_start0:
91+
.short 5 # DWARF version number
92+
.byte 1 # DWARF Unit Type
93+
.byte 8 # Address Size (in bytes)
94+
.long .debug_abbrev # Offset Into Abbrev. Section
95+
.byte 1 # Abbrev [1] 0xc:0x23 DW_TAG_compile_unit
96+
.byte 0 # DW_AT_producer
97+
.short 29 # DW_AT_language
98+
.byte 1 # DW_AT_name
99+
.long .Lstr_offsets_base0 # DW_AT_str_offsets_base
100+
.long .Lline_table_start0 # DW_AT_stmt_list
101+
.byte 2 # DW_AT_comp_dir
102+
.byte 0 # DW_AT_low_pc
103+
.long .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
104+
.long .Laddr_table_base0 # DW_AT_addr_base
105+
.byte 2 # Abbrev [2] 0x23:0xb DW_TAG_subprogram
106+
.byte 0 # DW_AT_low_pc
107+
.long .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
108+
.byte 1 # DW_AT_frame_base
109+
.byte 87
110+
.byte 3 # DW_AT_name
111+
.byte 0 # DW_AT_decl_file
112+
.byte 1 # DW_AT_decl_line
113+
# DW_AT_external
114+
.byte 0 # End Of Children Mark
115+
.Ldebug_info_end0:
116+
.section .debug_str_offsets,"",@progbits
117+
.long 20 # Length of String Offsets Set
118+
.short 5
119+
.short 0
120+
.Lstr_offsets_base0:
121+
.section .debug_str,"MS",@progbits,1
122+
.Linfo_string0:
123+
.asciz "clang version 20.1.8 (CentOS 20.1.8-1.el9)" # string offset=0
124+
.Linfo_string1:
125+
.asciz "main.c" # string offset=43
126+
.Linfo_string2:
127+
.asciz "/home/gpastukhov/tmp2" # string offset=50
128+
.Linfo_string3:
129+
.asciz "_start" # string offset=72
130+
.section .debug_str_offsets,"",@progbits
131+
.long .Linfo_string0
132+
.long .Linfo_string1
133+
.long .Linfo_string2
134+
.long .Linfo_string3
135+
.section .debug_addr,"",@progbits
136+
.long .Ldebug_addr_end0-.Ldebug_addr_start0 # Length of contribution
137+
.Ldebug_addr_start0:
138+
.short 5 # DWARF version number
139+
.byte 8 # Address size
140+
.byte 0 # Segment selector size
141+
.Laddr_table_base0:
142+
.quad .Lfunc_begin0
143+
.Ldebug_addr_end0:
144+
.ident "clang version 20.1.8 (CentOS 20.1.8-1.el9)"
145+
.section ".note.GNU-stack","",@progbits
146+
.addrsig
147+
.section .debug_line,"",@progbits
148+
.Lline_table_start0:

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