[llvm] [BOLT][DWARF] Slice .debug_str from the DWP for each CU (PR #159540)
Alexander Yermolovich via llvm-commits
llvm-commits at lists.llvm.org
Sun Nov 2 16:49:14 PST 2025
================
@@ -0,0 +1,380 @@
+#--- main.s
+# clang++ -g2 -gdwarf-4 -gsplit-dwarf=split -S main.cpp
+# extern int getReturn();
+# int main() {
+# return getReturn();
+# }
+ .file "main.cpp"
+ .globl main # -- Begin function main
+ .type main, at function
+main: # @main
+.Lfunc_begin0:
+ .file 1 "." "main.cpp"
+ .loc 1 2 0 # main.cpp:2:0
+ .loc 1 3 10 prologue_end # main.cpp:3:10
+ .loc 1 3 3 epilogue_begin is_stmt 0 # main.cpp:3:3
+ retq
+.Lfunc_end0:
+ .size main, .Lfunc_end0-main
+ .section .debug_abbrev,"", at progbits
+ .byte 1 # Abbreviation Code
+ .byte 17 # DW_TAG_compile_unit
+ .byte 0 # DW_CHILDREN_no
+ .byte 16 # DW_AT_stmt_list
+ .byte 23 # DW_FORM_sec_offset
+ .byte 27 # DW_AT_comp_dir
+ .byte 14 # DW_FORM_strp
+ .ascii "\264B" # DW_AT_GNU_pubnames
+ .byte 25 # DW_FORM_flag_present
+ .ascii "\260B" # DW_AT_GNU_dwo_name
+ .byte 14 # DW_FORM_strp
+ .ascii "\261B" # DW_AT_GNU_dwo_id
+ .byte 7 # DW_FORM_data8
+ .byte 17 # DW_AT_low_pc
+ .byte 1 # DW_FORM_addr
+ .byte 18 # DW_AT_high_pc
+ .byte 6 # DW_FORM_data4
+ .ascii "\263B" # DW_AT_GNU_addr_base
+ .byte 23 # DW_FORM_sec_offset
+ .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 4 # DWARF version number
+ .long .debug_abbrev # Offset Into Abbrev. Section
+ .byte 8 # Address Size (in bytes)
+ .byte 1 # Abbrev [1] 0xb:0x25 DW_TAG_compile_unit
+ .long .Lline_table_start0 # DW_AT_stmt_list
+ .long .Lskel_string0 # DW_AT_comp_dir
+ # DW_AT_GNU_pubnames
+ .long .Lskel_string1 # DW_AT_GNU_dwo_name
+ .quad -9094791692727444213 # DW_AT_GNU_dwo_id
+ .quad .Lfunc_begin0 # DW_AT_low_pc
+ .long .Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
+ .long .Laddr_table_base0 # DW_AT_GNU_addr_base
+.Ldebug_info_end0:
+ .section .debug_str,"MS", at progbits,1
+.Lskel_string0:
+ .asciz "." # string offset=0
+.Lskel_string1:
+ .asciz "main.dwo" # string offset=2
+ .section .debug_str.dwo,"eMS", at progbits,1
+.Linfo_string0:
+ .asciz "main" # string offset=0
+.Linfo_string1:
+ .asciz "int" # string offset=5
+.Linfo_string2:
+ .asciz "clang version 22.0.0" # string offset=9
+.Linfo_string3:
+ .asciz "main.cpp" # string offset=30
+.Linfo_string4:
+ .asciz "main.dwo" # string offset=39
+ .section .debug_str_offsets.dwo,"e", at progbits
+ .long 0
+ .long 5
+ .long 9
+ .long 30
+ .long 39
+ .section .debug_info.dwo,"e", at progbits
+ .long .Ldebug_info_dwo_end0-.Ldebug_info_dwo_start0 # Length of Unit
+.Ldebug_info_dwo_start0:
+ .short 4 # DWARF version number
+ .long 0 # Offset Into Abbrev. Section
+ .byte 8 # Address Size (in bytes)
+ .byte 1 # Abbrev [1] 0xb:0x22 DW_TAG_compile_unit
+ .byte 2 # DW_AT_producer
+ .short 33 # DW_AT_language
+ .byte 3 # DW_AT_name
+ .byte 4 # DW_AT_GNU_dwo_name
+ .quad -9094791692727444213 # DW_AT_GNU_dwo_id
+ .byte 2 # Abbrev [2] 0x19:0xf 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 0 # DW_AT_name
+ .byte 1 # DW_AT_decl_file
+ .byte 2 # DW_AT_decl_line
+ .long 40 # DW_AT_type
+ # DW_AT_external
+ .byte 3 # Abbrev [3] 0x28:0x4 DW_TAG_base_type
+ .byte 1 # DW_AT_name
+ .byte 5 # DW_AT_encoding
+ .byte 4 # DW_AT_byte_size
+ .byte 0 # End Of Children Mark
+.Ldebug_info_dwo_end0:
+ .section .debug_abbrev.dwo,"e", at progbits
+ .byte 1 # Abbreviation Code
+ .byte 17 # DW_TAG_compile_unit
+ .byte 1 # DW_CHILDREN_yes
+ .byte 37 # DW_AT_producer
+ .ascii "\202>" # DW_FORM_GNU_str_index
+ .byte 19 # DW_AT_language
+ .byte 5 # DW_FORM_data2
+ .byte 3 # DW_AT_name
+ .ascii "\202>" # DW_FORM_GNU_str_index
+ .ascii "\260B" # DW_AT_GNU_dwo_name
+ .ascii "\202>" # DW_FORM_GNU_str_index
+ .ascii "\261B" # DW_AT_GNU_dwo_id
+ .byte 7 # DW_FORM_data8
+ .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
+ .ascii "\201>" # DW_FORM_GNU_addr_index
+ .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
+ .ascii "\202>" # DW_FORM_GNU_str_index
+ .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
+ .ascii "\202>" # DW_FORM_GNU_str_index
+ .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_addr,"", at progbits
+.Laddr_table_base0:
+ .quad .Lfunc_begin0
+ .section .debug_gnu_pubnames,"", at progbits
----------------
ayermolo wrote:
I don't think pubnames/pubtypes are needed?
https://github.com/llvm/llvm-project/pull/159540
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