[llvm] 66e943b - [BOLT][DWARF] Fix for .debug_line with DWARF5

Alexander Yermolovich via llvm-commits llvm-commits at lists.llvm.org
Thu Jul 6 11:37:31 PDT 2023


Author: Alexander Yermolovich
Date: 2023-07-06T11:37:08-07:00
New Revision: 66e943b1a9751db1611f6ba07e4c46899455d686

URL: https://github.com/llvm/llvm-project/commit/66e943b1a9751db1611f6ba07e4c46899455d686
DIFF: https://github.com/llvm/llvm-project/commit/66e943b1a9751db1611f6ba07e4c46899455d686.diff

LOG: [BOLT][DWARF] Fix for .debug_line with DWARF5

There was a bug in a code that pre-populated line string for a case where parts
of .debug_line are not processed by BOLT, but copied as raw data. We were not
switching sections. This resulted in parts of the binary being over-written with
debug data.

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D154544

Added: 
    bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-helper-variable.s
    bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-helper.s
    bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-main.s
    bolt/test/X86/dwarf5-debug-line-not-modified.test

Modified: 
    bolt/lib/Core/DebugData.cpp
    llvm/include/llvm/MC/MCDwarf.h
    llvm/lib/MC/MCDwarf.cpp

Removed: 
    


################################################################################
diff  --git a/bolt/lib/Core/DebugData.cpp b/bolt/lib/Core/DebugData.cpp
index a96dde1d51d737..f142c02243f0fc 100644
--- a/bolt/lib/Core/DebugData.cpp
+++ b/bolt/lib/Core/DebugData.cpp
@@ -1655,25 +1655,27 @@ void DwarfLineTable::emitCU(MCStreamer *MCOS, MCDwarfLineTableParams Params,
 // Helper function to parse .debug_line_str, and populate one we are using.
 // For functions that we do not modify we output them as raw data.
 // Re-constructing .debug_line_str so that offsets are correct for those
-// debut line tables.
+// debug line tables.
 // Bonus is that when we output a final binary we can re-use .debug_line_str
 // section. So we don't have to do the SHF_ALLOC trick we did with
 // .debug_line.
 static void parseAndPopulateDebugLineStr(BinarySection &LineStrSection,
                                          MCDwarfLineStr &LineStr,
-                                         BinaryContext &BC,
-                                         MCStreamer &Streamer) {
+                                         BinaryContext &BC) {
   DataExtractor StrData(LineStrSection.getContents(),
                         BC.DwCtx->isLittleEndian(), 0);
   uint64_t Offset = 0;
   while (StrData.isValidOffset(Offset)) {
+    const uint64_t StrOffset = Offset;
     Error Err = Error::success();
     const char *CStr = StrData.getCStr(&Offset, &Err);
     if (Err) {
       errs() << "BOLT-ERROR: could not extract string from .debug_line_str";
       continue;
     }
-    LineStr.emitRef(&Streamer, CStr);
+    const size_t NewOffset = LineStr.addString(CStr);
+    assert(StrOffset == NewOffset &&
+           "New offset in .debug_line_str doesn't match original offset");
   }
 }
 
@@ -1693,11 +1695,12 @@ void DwarfLineTable::emit(BinaryContext &BC, MCStreamer &Streamer) {
   std::optional<MCDwarfLineStr> LineStr;
   ErrorOr<BinarySection &> LineStrSection =
       BC.getUniqueSectionByName(".debug_line_str");
+
   // Some versions of GCC output DWARF5 .debug_info, but DWARF4 or lower
-  // .debug_line
+  // .debug_line, so need to check if section exists.
   if (LineStrSection) {
     LineStr.emplace(*BC.Ctx);
-    parseAndPopulateDebugLineStr(*LineStrSection, *LineStr, BC, Streamer);
+    parseAndPopulateDebugLineStr(*LineStrSection, *LineStr, BC);
   }
 
   // Switch to the section where the table will be emitted into.

diff  --git a/bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-helper-variable.s b/bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-helper-variable.s
new file mode 100644
index 00000000000000..5a9711c710dfa2
--- /dev/null
+++ b/bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-helper-variable.s
@@ -0,0 +1,129 @@
+# int Foo = 0;
+
+	.text
+	.file	"helperVariable.cpp"
+	.file	0 "/test" "helperVariable.cpp" md5 0xb6e6130198b21a44b5db4247fccb359d
+	.type	Foo, at object                     # @Foo
+	.bss
+	.globl	Foo
+	.p2align	2, 0x0
+Foo:
+	.long	0                               # 0x0
+	.size	Foo, 4
+
+	.section	.debug_abbrev,"", at progbits
+	.byte	1                               # Abbreviation Code
+	.byte	17                              # DW_TAG_compile_unit
+	.byte	1                               # DW_CHILDREN_yes
+	.byte	37                              # DW_AT_producer
+	.byte	37                              # DW_FORM_strx1
+	.byte	19                              # DW_AT_language
+	.byte	5                               # DW_FORM_data2
+	.byte	3                               # DW_AT_name
+	.byte	37                              # DW_FORM_strx1
+	.byte	114                             # DW_AT_str_offsets_base
+	.byte	23                              # DW_FORM_sec_offset
+	.byte	16                              # DW_AT_stmt_list
+	.byte	23                              # DW_FORM_sec_offset
+	.byte	27                              # DW_AT_comp_dir
+	.byte	37                              # DW_FORM_strx1
+	.byte	115                             # DW_AT_addr_base
+	.byte	23                              # DW_FORM_sec_offset
+	.byte	0                               # EOM(1)
+	.byte	0                               # EOM(2)
+	.byte	2                               # Abbreviation Code
+	.byte	52                              # DW_TAG_variable
+	.byte	0                               # DW_CHILDREN_no
+	.byte	3                               # DW_AT_name
+	.byte	37                              # DW_FORM_strx1
+	.byte	73                              # DW_AT_type
+	.byte	19                              # DW_FORM_ref4
+	.byte	63                              # DW_AT_external
+	.byte	25                              # DW_FORM_flag_present
+	.byte	58                              # DW_AT_decl_file
+	.byte	11                              # DW_FORM_data1
+	.byte	59                              # DW_AT_decl_line
+	.byte	11                              # DW_FORM_data1
+	.byte	2                               # DW_AT_location
+	.byte	24                              # DW_FORM_exprloc
+	.byte	0                               # EOM(1)
+	.byte	0                               # EOM(2)
+	.byte	3                               # Abbreviation Code
+	.byte	36                              # DW_TAG_base_type
+	.byte	0                               # DW_CHILDREN_no
+	.byte	3                               # DW_AT_name
+	.byte	37                              # DW_FORM_strx1
+	.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	.debug_info,"", at progbits
+.Lcu_begin0:
+	.long	.Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
+.Ldebug_info_start0:
+	.short	5                               # DWARF version number
+	.byte	1                               # DWARF Unit Type
+	.byte	8                               # Address Size (in bytes)
+	.long	.debug_abbrev                   # Offset Into Abbrev. Section
+	.byte	1                               # Abbrev [1] 0xc:0x22 DW_TAG_compile_unit
+	.byte	0                               # DW_AT_producer
+	.short	33                              # DW_AT_language
+	.byte	1                               # DW_AT_name
+	.long	.Lstr_offsets_base0             # DW_AT_str_offsets_base
+	.long	.Lline_table_start0             # DW_AT_stmt_list
+	.byte	2                               # DW_AT_comp_dir
+	.long	.Laddr_table_base0              # DW_AT_addr_base
+	.byte	2                               # Abbrev [2] 0x1e:0xb DW_TAG_variable
+	.byte	3                               # DW_AT_name
+	.long	41                              # DW_AT_type
+                                        # DW_AT_external
+	.byte	0                               # DW_AT_decl_file
+	.byte	1                               # DW_AT_decl_line
+	.byte	2                               # DW_AT_location
+	.byte	161
+	.byte	0
+	.byte	3                               # Abbrev [3] 0x29:0x4 DW_TAG_base_type
+	.byte	4                               # DW_AT_name
+	.byte	5                               # DW_AT_encoding
+	.byte	4                               # DW_AT_byte_size
+	.byte	0                               # End Of Children Mark
+.Ldebug_info_end0:
+	.section	.debug_str_offsets,"", at progbits
+	.long	24                              # Length of String Offsets Set
+	.short	5
+	.short	0
+.Lstr_offsets_base0:
+	.section	.debug_str,"MS", at progbits,1
+.Linfo_string0:
+	.asciz	"clang version 17.0.0 (https://github.com/llvm/llvm-project.git 640e07c49037cca41a1bfbeb916b569d8c950aea)" # string offset=0
+.Linfo_string1:
+	.asciz	"helperVariable.cpp"            # string offset=105
+.Linfo_string2:
+	.asciz	"/test" # string offset=124
+.Linfo_string3:
+	.asciz	"Foo"                           # string offset=162
+.Linfo_string4:
+	.asciz	"int"                           # string offset=166
+	.section	.debug_str_offsets,"", at progbits
+	.long	.Linfo_string0
+	.long	.Linfo_string1
+	.long	.Linfo_string2
+	.long	.Linfo_string3
+	.long	.Linfo_string4
+	.section	.debug_addr,"", at progbits
+	.long	.Ldebug_addr_end0-.Ldebug_addr_start0 # Length of contribution
+.Ldebug_addr_start0:
+	.short	5                               # DWARF version number
+	.byte	8                               # Address size
+	.byte	0                               # Segment selector size
+.Laddr_table_base0:
+	.quad	Foo
+.Ldebug_addr_end0:
+	.ident	"clang version 17.0.0 (https://github.com/llvm/llvm-project.git 640e07c49037cca41a1bfbeb916b569d8c950aea)"
+	.section	".note.GNU-stack","", at progbits
+	.addrsig
+	.section	.debug_line,"", at progbits
+.Lline_table_start0:

diff  --git a/bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-helper.s b/bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-helper.s
new file mode 100644
index 00000000000000..f70a3dcc8121f7
--- /dev/null
+++ b/bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-helper.s
@@ -0,0 +1,165 @@
+# int foo() {
+#   return 0;
+# }
+
+	.text
+	.file	"helper.cpp"
+	.globl	_Z3foov                         # -- Begin function _Z3foov
+	.p2align	4, 0x90
+	.type	_Z3foov, at function
+_Z3foov:                                # @_Z3foov
+.Lfunc_begin0:
+	.file	0 "/test" "helper.cpp" md5 0x95a4a33e7fe9423970d3c798fdf8ed43
+	.loc	0 1 0                           # helper.cpp:1:0
+	.cfi_startproc
+# %bb.0:                                # %entry
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset %rbp, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register %rbp
+.Ltmp0:
+	.loc	0 2 3 prologue_end              # helper.cpp:2:3
+	xorl	%eax, %eax
+	.loc	0 2 3 epilogue_begin is_stmt 0  # helper.cpp:2:3
+	popq	%rbp
+	.cfi_def_cfa %rsp, 8
+	retq
+.Ltmp1:
+.Lfunc_end0:
+	.size	_Z3foov, .Lfunc_end0-_Z3foov
+	.cfi_endproc
+                                        # -- End function
+	.section	.debug_abbrev,"", at progbits
+	.byte	1                               # Abbreviation Code
+	.byte	17                              # DW_TAG_compile_unit
+	.byte	1                               # DW_CHILDREN_yes
+	.byte	37                              # DW_AT_producer
+	.byte	37                              # DW_FORM_strx1
+	.byte	19                              # DW_AT_language
+	.byte	5                               # DW_FORM_data2
+	.byte	3                               # DW_AT_name
+	.byte	37                              # DW_FORM_strx1
+	.byte	114                             # DW_AT_str_offsets_base
+	.byte	23                              # DW_FORM_sec_offset
+	.byte	16                              # DW_AT_stmt_list
+	.byte	23                              # DW_FORM_sec_offset
+	.byte	27                              # DW_AT_comp_dir
+	.byte	37                              # DW_FORM_strx1
+	.byte	17                              # DW_AT_low_pc
+	.byte	27                              # DW_FORM_addrx
+	.byte	18                              # DW_AT_high_pc
+	.byte	6                               # DW_FORM_data4
+	.byte	115                             # DW_AT_addr_base
+	.byte	23                              # DW_FORM_sec_offset
+	.byte	0                               # EOM(1)
+	.byte	0                               # EOM(2)
+	.byte	2                               # Abbreviation Code
+	.byte	46                              # DW_TAG_subprogram
+	.byte	0                               # DW_CHILDREN_no
+	.byte	17                              # DW_AT_low_pc
+	.byte	27                              # DW_FORM_addrx
+	.byte	18                              # DW_AT_high_pc
+	.byte	6                               # DW_FORM_data4
+	.byte	64                              # DW_AT_frame_base
+	.byte	24                              # DW_FORM_exprloc
+	.byte	110                             # DW_AT_linkage_name
+	.byte	37                              # DW_FORM_strx1
+	.byte	3                               # DW_AT_name
+	.byte	37                              # DW_FORM_strx1
+	.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	63                              # DW_AT_external
+	.byte	25                              # DW_FORM_flag_present
+	.byte	0                               # EOM(1)
+	.byte	0                               # EOM(2)
+	.byte	3                               # Abbreviation Code
+	.byte	36                              # DW_TAG_base_type
+	.byte	0                               # DW_CHILDREN_no
+	.byte	3                               # DW_AT_name
+	.byte	37                              # DW_FORM_strx1
+	.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	.debug_info,"", at progbits
+.Lcu_begin0:
+	.long	.Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
+.Ldebug_info_start0:
+	.short	5                               # DWARF version number
+	.byte	1                               # DWARF Unit Type
+	.byte	8                               # Address Size (in bytes)
+	.long	.debug_abbrev                   # Offset Into Abbrev. Section
+	.byte	1                               # Abbrev [1] 0xc:0x2c DW_TAG_compile_unit
+	.byte	0                               # DW_AT_producer
+	.short	33                              # DW_AT_language
+	.byte	1                               # DW_AT_name
+	.long	.Lstr_offsets_base0             # DW_AT_str_offsets_base
+	.long	.Lline_table_start0             # DW_AT_stmt_list
+	.byte	2                               # DW_AT_comp_dir
+	.byte	0                               # DW_AT_low_pc
+	.long	.Lfunc_end0-.Lfunc_begin0       # DW_AT_high_pc
+	.long	.Laddr_table_base0              # DW_AT_addr_base
+	.byte	2                               # Abbrev [2] 0x23:0x10 DW_TAG_subprogram
+	.byte	0                               # DW_AT_low_pc
+	.long	.Lfunc_end0-.Lfunc_begin0       # DW_AT_high_pc
+	.byte	1                               # DW_AT_frame_base
+	.byte	86
+	.byte	3                               # DW_AT_linkage_name
+	.byte	4                               # DW_AT_name
+	.byte	0                               # DW_AT_decl_file
+	.byte	1                               # DW_AT_decl_line
+	.long	51                              # DW_AT_type
+                                        # DW_AT_external
+	.byte	3                               # Abbrev [3] 0x33:0x4 DW_TAG_base_type
+	.byte	5                               # DW_AT_name
+	.byte	5                               # DW_AT_encoding
+	.byte	4                               # DW_AT_byte_size
+	.byte	0                               # End Of Children Mark
+.Ldebug_info_end0:
+	.section	.debug_str_offsets,"", at progbits
+	.long	28                              # Length of String Offsets Set
+	.short	5
+	.short	0
+.Lstr_offsets_base0:
+	.section	.debug_str,"MS", at progbits,1
+.Linfo_string0:
+	.asciz	"clang version 17.0.0 (https://github.com/llvm/llvm-project.git 640e07c49037cca41a1bfbeb916b569d8c950aea)" # string offset=0
+.Linfo_string1:
+	.asciz	"helper.cpp"                    # string offset=105
+.Linfo_string2:
+	.asciz	"/test" # string offset=116
+.Linfo_string3:
+	.asciz	"_Z3foov"                       # string offset=154
+.Linfo_string4:
+	.asciz	"foo"                           # string offset=162
+.Linfo_string5:
+	.asciz	"int"                           # string offset=166
+	.section	.debug_str_offsets,"", at progbits
+	.long	.Linfo_string0
+	.long	.Linfo_string1
+	.long	.Linfo_string2
+	.long	.Linfo_string3
+	.long	.Linfo_string4
+	.long	.Linfo_string5
+	.section	.debug_addr,"", at progbits
+	.long	.Ldebug_addr_end0-.Ldebug_addr_start0 # Length of contribution
+.Ldebug_addr_start0:
+	.short	5                               # DWARF version number
+	.byte	8                               # Address size
+	.byte	0                               # Segment selector size
+.Laddr_table_base0:
+	.quad	.Lfunc_begin0
+.Ldebug_addr_end0:
+	.ident	"clang version 17.0.0 (https://github.com/llvm/llvm-project.git 640e07c49037cca41a1bfbeb916b569d8c950aea)"
+	.section	".note.GNU-stack","", at progbits
+	.addrsig
+	.section	.debug_line,"", at progbits
+.Lline_table_start0:

diff  --git a/bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-main.s b/bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-main.s
new file mode 100644
index 00000000000000..df42ed1c7ace04
--- /dev/null
+++ b/bolt/test/X86/Inputs/dwarf5-debug-line-not-modified-main.s
@@ -0,0 +1,160 @@
+# int main() {
+#  return 0;
+# }
+
+	.text
+	.file	"main.cpp"
+	.globl	main                            # -- Begin function main
+	.p2align	4, 0x90
+	.type	main, at function
+main:                                   # @main
+.Lfunc_begin0:
+	.file	0 "/test" "main.cpp" md5 0x7228a872dc174332f3151a7ac3344b26
+	.loc	0 1 0                           # main.cpp:1:0
+	.cfi_startproc
+# %bb.0:                                # %entry
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset %rbp, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register %rbp
+	movl	$0, -4(%rbp)
+.Ltmp0:
+	.loc	0 2 2 prologue_end              # main.cpp:2:2
+	xorl	%eax, %eax
+	.loc	0 2 2 epilogue_begin is_stmt 0  # main.cpp:2:2
+	popq	%rbp
+	.cfi_def_cfa %rsp, 8
+	retq
+.Ltmp1:
+.Lfunc_end0:
+	.size	main, .Lfunc_end0-main
+	.cfi_endproc
+                                        # -- End function
+	.section	.debug_abbrev,"", at progbits
+	.byte	1                               # Abbreviation Code
+	.byte	17                              # DW_TAG_compile_unit
+	.byte	1                               # DW_CHILDREN_yes
+	.byte	37                              # DW_AT_producer
+	.byte	37                              # DW_FORM_strx1
+	.byte	19                              # DW_AT_language
+	.byte	5                               # DW_FORM_data2
+	.byte	3                               # DW_AT_name
+	.byte	37                              # DW_FORM_strx1
+	.byte	114                             # DW_AT_str_offsets_base
+	.byte	23                              # DW_FORM_sec_offset
+	.byte	16                              # DW_AT_stmt_list
+	.byte	23                              # DW_FORM_sec_offset
+	.byte	27                              # DW_AT_comp_dir
+	.byte	37                              # DW_FORM_strx1
+	.byte	17                              # DW_AT_low_pc
+	.byte	27                              # DW_FORM_addrx
+	.byte	18                              # DW_AT_high_pc
+	.byte	6                               # DW_FORM_data4
+	.byte	115                             # DW_AT_addr_base
+	.byte	23                              # DW_FORM_sec_offset
+	.byte	0                               # EOM(1)
+	.byte	0                               # EOM(2)
+	.byte	2                               # Abbreviation Code
+	.byte	46                              # DW_TAG_subprogram
+	.byte	0                               # DW_CHILDREN_no
+	.byte	17                              # DW_AT_low_pc
+	.byte	27                              # DW_FORM_addrx
+	.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	37                              # DW_FORM_strx1
+	.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	63                              # DW_AT_external
+	.byte	25                              # DW_FORM_flag_present
+	.byte	0                               # EOM(1)
+	.byte	0                               # EOM(2)
+	.byte	3                               # Abbreviation Code
+	.byte	36                              # DW_TAG_base_type
+	.byte	0                               # DW_CHILDREN_no
+	.byte	3                               # DW_AT_name
+	.byte	37                              # DW_FORM_strx1
+	.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	.debug_info,"", at progbits
+.Lcu_begin0:
+	.long	.Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
+.Ldebug_info_start0:
+	.short	5                               # DWARF version number
+	.byte	1                               # DWARF Unit Type
+	.byte	8                               # Address Size (in bytes)
+	.long	.debug_abbrev                   # Offset Into Abbrev. Section
+	.byte	1                               # Abbrev [1] 0xc:0x2b DW_TAG_compile_unit
+	.byte	0                               # DW_AT_producer
+	.short	33                              # DW_AT_language
+	.byte	1                               # DW_AT_name
+	.long	.Lstr_offsets_base0             # DW_AT_str_offsets_base
+	.long	.Lline_table_start0             # DW_AT_stmt_list
+	.byte	2                               # DW_AT_comp_dir
+	.byte	0                               # DW_AT_low_pc
+	.long	.Lfunc_end0-.Lfunc_begin0       # DW_AT_high_pc
+	.long	.Laddr_table_base0              # DW_AT_addr_base
+	.byte	2                               # Abbrev [2] 0x23:0xf DW_TAG_subprogram
+	.byte	0                               # DW_AT_low_pc
+	.long	.Lfunc_end0-.Lfunc_begin0       # DW_AT_high_pc
+	.byte	1                               # DW_AT_frame_base
+	.byte	86
+	.byte	3                               # DW_AT_name
+	.byte	0                               # DW_AT_decl_file
+	.byte	1                               # DW_AT_decl_line
+	.long	50                              # DW_AT_type
+                                        # DW_AT_external
+	.byte	3                               # Abbrev [3] 0x32:0x4 DW_TAG_base_type
+	.byte	4                               # DW_AT_name
+	.byte	5                               # DW_AT_encoding
+	.byte	4                               # DW_AT_byte_size
+	.byte	0                               # End Of Children Mark
+.Ldebug_info_end0:
+	.section	.debug_str_offsets,"", at progbits
+	.long	24                              # Length of String Offsets Set
+	.short	5
+	.short	0
+.Lstr_offsets_base0:
+	.section	.debug_str,"MS", at progbits,1
+.Linfo_string0:
+	.asciz	"clang version 17.0.0 (https://github.com/llvm/llvm-project.git 640e07c49037cca41a1bfbeb916b569d8c950aea)" # string offset=0
+.Linfo_string1:
+	.asciz	"main.cpp"                      # string offset=105
+.Linfo_string2:
+	.asciz	"/test" # string offset=114
+.Linfo_string3:
+	.asciz	"main"                          # string offset=152
+.Linfo_string4:
+	.asciz	"int"                           # string offset=157
+	.section	.debug_str_offsets,"", at progbits
+	.long	.Linfo_string0
+	.long	.Linfo_string1
+	.long	.Linfo_string2
+	.long	.Linfo_string3
+	.long	.Linfo_string4
+	.section	.debug_addr,"", at progbits
+	.long	.Ldebug_addr_end0-.Ldebug_addr_start0 # Length of contribution
+.Ldebug_addr_start0:
+	.short	5                               # DWARF version number
+	.byte	8                               # Address size
+	.byte	0                               # Segment selector size
+.Laddr_table_base0:
+	.quad	.Lfunc_begin0
+.Ldebug_addr_end0:
+	.ident	"clang version 17.0.0 (https://github.com/llvm/llvm-project.git 640e07c49037cca41a1bfbeb916b569d8c950aea)"
+	.section	".note.GNU-stack","", at progbits
+	.addrsig
+	.section	.debug_line,"", at progbits
+.Lline_table_start0:

diff  --git a/bolt/test/X86/dwarf5-debug-line-not-modified.test b/bolt/test/X86/dwarf5-debug-line-not-modified.test
new file mode 100644
index 00000000000000..20dd9083169acf
--- /dev/null
+++ b/bolt/test/X86/dwarf5-debug-line-not-modified.test
@@ -0,0 +1,29 @@
+# REQUIRES: system-linux
+
+# RUN: llvm-mc -dwarf-version=5 -filetype=obj -triple x86_64-unknown-linux %p/Inputs/dwarf5-debug-line-not-modified-main.s -o %t1.o
+# RUN: llvm-mc -dwarf-version=5 -filetype=obj -triple x86_64-unknown-linux %p/Inputs/dwarf5-debug-line-not-modified-helper-variable.s -o %t2.o
+# RUN: llvm-mc -dwarf-version=5 -filetype=obj -triple x86_64-unknown-linux %p/Inputs/dwarf5-debug-line-not-modified-helper.s -o %t3.o
+# RUN: %clang %cflags -dwarf-5 %t1.o %t2.o %t3.o -o %t.exe -Wl,-q
+# RUN: llvm-bolt %t.exe -o %t.bolt --update-debug-sections
+# RUN: llvm-dwarfdump --show-form --verbose --debug-line %t.bolt | FileCheck --check-prefix=POSTCHECK %s
+
+# This test checks that BOLT generates correct debug_line_str when one of CU contributions is not modified.
+
+# POSTCHECK: version: 5
+# POSTCHECK: include_directories[  0] =  .debug_line_str[{{.*}}] = "/test"
+# POSTCHECK: file_names[  0]:
+# POSTCHECK: name:  .debug_line_str[{{.*}}] = "main.cpp"
+# POSTCHECK: dir_index: 0
+# POSTCHECK: md5_checksum: 7228a872dc174332f3151a7ac3344b26
+# POSTCHECK: version: 5
+# POSTCHECK: include_directories[  0] =  .debug_line_str[{{.*}}] = "/test"
+# POSTCHECK: file_names[  0]:
+# POSTCHECK: name:  .debug_line_str[{{.*}}] = "helperVariable.cpp"
+# POSTCHECK: dir_index: 0
+# POSTCHECK: md5_checksum: b6e6130198b21a44b5db4247fccb359d
+# POSTCHECK: version: 5
+# POSTCHECK: include_directories[  0] =  .debug_line_str[{{.*}}] = "/test"
+# POSTCHECK: file_names[  0]:
+# POSTCHECK: name:  .debug_line_str[{{.*}}] = "helper.cpp"
+# POSTCHECK: dir_index: 0
+# POSTCHECK: md5_checksum: 95a4a33e7fe9423970d3c798fdf8ed43

diff  --git a/llvm/include/llvm/MC/MCDwarf.h b/llvm/include/llvm/MC/MCDwarf.h
index 7dc1c383bbf3f2..715714f8e55dbb 100644
--- a/llvm/include/llvm/MC/MCDwarf.h
+++ b/llvm/include/llvm/MC/MCDwarf.h
@@ -70,6 +70,10 @@ class MCDwarfLineStr {
 
   /// Returns finalized section.
   SmallString<0> getFinalizedData();
+
+  /// Adds path \p Path to the line string. Returns offset in the
+  /// .debug_line_str section.
+  size_t addString(StringRef Path);
 };
 
 /// Instances of this class represent the name of the dwarf .file directive and

diff  --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index 177f957a3f377f..55632f2fe76a68 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -350,10 +350,14 @@ SmallString<0> MCDwarfLineStr::getFinalizedData() {
   return Data;
 }
 
+size_t MCDwarfLineStr::addString(StringRef Path) {
+  return LineStrings.add(Path);
+}
+
 void MCDwarfLineStr::emitRef(MCStreamer *MCOS, StringRef Path) {
   int RefSize =
       dwarf::getDwarfOffsetByteSize(MCOS->getContext().getDwarfFormat());
-  size_t Offset = LineStrings.add(Path);
+  size_t Offset = addString(Path);
   if (UseRelocs) {
     MCContext &Ctx = MCOS->getContext();
     MCOS->emitValue(makeStartPlusIntExpr(Ctx, *LineStrLabel, Offset), RefSize);


        


More information about the llvm-commits mailing list