[BOLT][DWARF] Don't create extra .debug_str_offsets contributions

With ThinLTO mutliple CUs can share the same .debug_str_offsets contribution. We
were creating a new one for each CU. This lead to a binary size increase.

Reviewed By: maksfb

Differential Revision: https://reviews.llvm.org/D139214

1 files changed, 304 insertions, 0 deletions

diff --git a/bolt/test/X86/dwarf5-shared-str-offset-base.s b/bolt/test/X86/dwarf5-shared-str-offset-base.s
new file mode 100644
index 000000000000..0756d537b25a
--- /dev/null
+++ b/bolt/test/X86/dwarf5-shared-str-offset-base.s
@@ -0,0 +1,304 @@
+# REQUIRES: system-linux
+
+# RUN: llvm-mc --filetype=obj --triple x86_64 %s -o %tmain.o --defsym MAIN=0
+# RUN: llvm-mc --filetype=obj --triple x86_64 %s -o %thelper.o
+# RUN: %clang %cflags %tmain.o %thelper.o -o %tmain.exe
+# RUN: llvm-bolt %tmain.exe -o %tmain.exe.bolt --update-debug-sections
+# RUN: llvm-dwarfdump --debug-info %tmain.exe.bolt > %tout.text
+# RUN: llvm-dwarfdump --show-section-sizes %tmain.exe >> %tout.text
+# RUN: llvm-dwarfdump --show-section-sizes %tmain.exe.bolt >> %tout.text
+# RUN: cat %tout.text | FileCheck %s
+
+# This test checks that with DWARF5 when two CUs share the same .debug_str_offsets
+# entry BOLT does not create a duplicate.
+
+# CHECK: DW_AT_str_offsets_base (0x[[#%.8x,ADDR:]]
+# CHECK: DW_AT_str_offsets_base (0x[[#ADDR]]
+
+# CHECK: .debug_str_offsets [[#ADDR2:]]
+# CHECK: .debug_str_offsets [[#ADDR2]]
+
+# main.cpp
+# int main(){
+# 	return 0;
+# }
+
+# helper.cpp
+# void foo(){}
+
+## Create two CUs, with dwo_ids 0 and 1 respectively.
+.ifdef MAIN
+.text
+	.file	"main.cpp"
+	.globl	main                            # -- Begin function main
+	.p2align	4, 0x90
+	.type	main,@function
+main:                                   # @main
+.Lfunc_begin0:
+	.file	0 "." "main.cpp" md5 0x32c197b0a8b855eb3d7573c993ada862
+	.loc	0 1 0                           # main.cpp:1:0
+	.cfi_startproc
+# %bb.0:
+	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 1 prologue_end              # main.cpp:2:1
+	xorl	%eax, %eax
+	popq	%rbp
+	.cfi_def_cfa %rsp, 8
+	retq
+.Ltmp1:
+.Lfunc_end0:
+	.size	main, .Lfunc_end0-main
+	.cfi_endproc
+                                        # -- End function
+	.section	.debug_abbrev,"",@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,"",@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,"",@progbits
+	.long	24                              # Length of String Offsets Set
+	.short	5
+	.short	0
+.Lstr_offsets_base0:
+	.section	.debug_str,"MS",@progbits,1
+.Linfo_string0:
+	.asciz	"clang version 15.0.0" # string offset=0
+.Linfo_string1:
+	.asciz	"main.cpp"                      # string offset=146
+.Linfo_string2:
+	.asciz	"." # string offset=155
+.Linfo_string3:
+	.asciz	"main"                          # string offset=198
+.Linfo_string4:
+	.asciz	"int"                           # string offset=203
+	.section	.debug_str_offsets,"",@progbits
+	.long	.Linfo_string0
+	.long	.Linfo_string1
+	.long	.Linfo_string2
+	.long	.Linfo_string3
+	.long	.Linfo_string4
+	.section	.debug_addr,"",@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 15.0.0"
+	.section	".note.GNU-stack","",@progbits
+	.addrsig
+	.section	.debug_line,"",@progbits
+.Lline_table_start0:
+.else
+.text
+	.file	"helper.cpp"
+	.globl	_Z3foov                         # -- Begin function _Z3foov
+	.p2align	4, 0x90
+	.type	_Z3foov,@function
+_Z3foov:                                # @_Z3foov
+.Lfunc_begin0:
+	.file	0 "." "helper.cpp" md5 0x5f98e4807e4f8781c26a82faf819f8a7
+	.loc	0 1 0                           # helper.cpp:1:0
+	.cfi_startproc
+# %bb.0:
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset %rbp, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register %rbp
+.Ltmp0:
+	.loc	0 1 12 prologue_end             # helper.cpp:1:12
+	popq	%rbp
+	.cfi_def_cfa %rsp, 8
+	retq
+.Ltmp1:
+.Lfunc_end0:
+	.size	_Z3foov, .Lfunc_end0-_Z3foov
+	.cfi_endproc
+                                        # -- End function
+	.section	.debug_abbrev,"",@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	63                              # DW_AT_external
+	.byte	25                              # DW_FORM_flag_present
+	.byte	0                               # EOM(1)
+	.byte	0                               # EOM(2)
+	.byte	0                               # EOM(3)
+	.section	.debug_info,"",@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:0x24 DW_TAG_compile_unit
+	.byte	0                               # DW_AT_producer
+	.short	33                              # DW_AT_language
+	.byte	1                               # DW_AT_name
+	.long	0x8				                # DW_AT_str_offsets_base Manually modified to be the same as first CU
+	.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] 0x23:0xc 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
+                                        # DW_AT_external
+	.byte	0                               # End Of Children Mark
+.Ldebug_info_end0:
+# Manually removed .debug_str_offsets and .debug_str
+	.section	.debug_addr,"",@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 15.0.0"
+	.section	".note.GNU-stack","",@progbits
+	.addrsig
+	.section	.debug_line,"",@progbits
+.Lline_table_start0:
+.endif