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[lldb] Skip declaration DIEs in the debug_names index (#94744)
This makes sure we try to process declaration DIEs that are erroneously present in the index. Until bd5c636, clang was emitting index entries for declaration DIEs with DW_AT_signature attributes. This makes sure to avoid returning those DIEs as the definitions of a type, but also makes sure to pass through DIEs referring to static constexpr member variables, which is a (probably nonconforming) extension used by dsymutil. It adds test cases for both of the scenarios. It is essentially a recommit of #91808.
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‎lldb/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp

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@@ -85,6 +85,11 @@ bool DebugNamesDWARFIndex::ProcessEntry(
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DWARFDIE die = GetDIE(entry);
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if (!die)
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return true;
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// Clang used to erroneously emit index entries for declaration DIEs in case
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// when the definition is in a type unit (llvm.org/pr77696).
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if (die.IsStructUnionOrClass() &&
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die.GetAttributeValueAsUnsigned(DW_AT_declaration, 0))
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return true;
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return callback(die);
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}
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‎lldb/test/Shell/SymbolFile/DWARF/x86/debug-names-signature.s

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## Test that we can correctly complete types even if the debug_names index
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## contains entries referring to declaration dies (clang emitted entries like
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## that until bd5c6367bd7).
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##
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## This test consists of two compile units and one type unit. CU1 has the
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## definition of a variable, but only a forward-declaration of its type. When
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## attempting to find a definition, the debug_names lookup will return the DIE
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## in CU0, which is also a forward-declaration (with a reference to a type
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## unit). LLDB needs to find the definition of the type within the type unit.
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# RUN: llvm-mc -triple=x86_64-pc-linux -filetype=obj %s > %t
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# RUN: %lldb %t -o "target variable s" -o exit | FileCheck %s
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# CHECK: (lldb) target variable s
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# CHECK-NEXT: (Struct) s = (member = 47)
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.data
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.p2align 2, 0x0
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.long 0
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s:
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.long 47 # 0x2f
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.section .debug_abbrev,"",@progbits
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.byte 1 # Abbreviation Code
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.byte 65 # DW_TAG_type_unit
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.byte 1 # DW_CHILDREN_yes
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.byte 19 # DW_AT_language
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.byte 5 # DW_FORM_data2
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 2 # Abbreviation Code
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.byte 19 # DW_TAG_structure_type
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.byte 1 # DW_CHILDREN_yes
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.byte 54 # DW_AT_calling_convention
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.byte 11 # DW_FORM_data1
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.byte 3 # DW_AT_name
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.byte 14 # DW_FORM_strp
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.byte 11 # DW_AT_byte_size
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.byte 11 # DW_FORM_data1
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 3 # Abbreviation Code
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.byte 13 # DW_TAG_member
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.byte 0 # DW_CHILDREN_no
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.byte 3 # DW_AT_name
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.byte 14 # DW_FORM_strp
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.byte 73 # DW_AT_type
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.byte 19 # DW_FORM_ref4
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.byte 56 # DW_AT_data_member_location
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.byte 11 # DW_FORM_data1
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 4 # Abbreviation Code
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.byte 36 # DW_TAG_base_type
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.byte 0 # DW_CHILDREN_no
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.byte 3 # DW_AT_name
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.byte 14 # DW_FORM_strp
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.byte 62 # DW_AT_encoding
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.byte 11 # DW_FORM_data1
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.byte 11 # DW_AT_byte_size
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.byte 11 # DW_FORM_data1
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 5 # Abbreviation Code
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.byte 17 # DW_TAG_compile_unit
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.byte 1 # DW_CHILDREN_yes
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.byte 37 # DW_AT_producer
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.byte 8 # DW_FORM_string
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.byte 19 # DW_AT_language
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.byte 5 # DW_FORM_data2
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 6 # Abbreviation Code
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.byte 52 # DW_TAG_variable
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.byte 0 # DW_CHILDREN_no
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.byte 3 # DW_AT_name
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.byte 14 # DW_FORM_strp
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.byte 73 # DW_AT_type
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.byte 19 # DW_FORM_ref4
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.byte 2 # DW_AT_location
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.byte 24 # DW_FORM_exprloc
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 7 # Abbreviation Code
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.byte 19 # DW_TAG_structure_type
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.byte 0 # DW_CHILDREN_no
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.byte 60 # DW_AT_declaration
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.byte 25 # DW_FORM_flag_present
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.byte 105 # DW_AT_signature
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.byte 32 # DW_FORM_ref_sig8
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 8 # Abbreviation Code
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.byte 19 # DW_TAG_structure_type
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.byte 0 # DW_CHILDREN_no
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.byte 3 # DW_AT_name
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.byte 14 # DW_FORM_strp
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.byte 60 # DW_AT_declaration
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.byte 25 # DW_FORM_flag_present
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.byte 0 # EOM(1)
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.byte 0 # EOM(2)
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.byte 0 # EOM(3)
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.section .debug_info,"",@progbits
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.Ltu_begin0:
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.long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
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.Ldebug_info_start0:
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.short 5 # DWARF version number
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.byte 2 # DWARF Unit Type
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.byte 8 # Address Size (in bytes)
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.long .debug_abbrev # Offset Into Abbrev. Section
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.quad 4878254330033667422 # Type Signature
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.long .LStruct_def-.Ltu_begin0 # Type DIE Offset
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.byte 1 # Abbrev [1] 0x18:0x20 DW_TAG_type_unit
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.short 33 # DW_AT_language
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.LStruct_def:
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.byte 2 # Abbrev [2] 0x23:0x10 DW_TAG_structure_type
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.byte 5 # DW_AT_calling_convention
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.long .Linfo_string6 # DW_AT_name
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.byte 4 # DW_AT_byte_size
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.byte 3 # Abbrev [3] 0x29:0x9 DW_TAG_member
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.long .Linfo_string4 # DW_AT_name
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.long .Lint-.Ltu_begin0 # DW_AT_type
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.byte 0 # DW_AT_data_member_location
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.byte 0 # End Of Children Mark
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.Lint:
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.byte 4 # Abbrev [4] 0x33:0x4 DW_TAG_base_type
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.long .Linfo_string5 # DW_AT_name
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.byte 5 # DW_AT_encoding
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.byte 4 # DW_AT_byte_size
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.byte 0 # End Of Children Mark
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.Ldebug_info_end0:
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.Lcu_begin0:
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.long .Ldebug_info_end1-.Ldebug_info_start1 # Length of Unit
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.Ldebug_info_start1:
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.short 5 # DWARF version number
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.byte 1 # DWARF Unit Type
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.byte 8 # Address Size (in bytes)
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.long .debug_abbrev # Offset Into Abbrev. Section
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.byte 5 # Abbrev [5] 0xc:0x27 DW_TAG_compile_unit
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.asciz "Hand-written DWARF" # DW_AT_producer
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.short 33 # DW_AT_language
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.Ls:
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.byte 6 # Abbrev [6] 0x1e:0xb DW_TAG_variable
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.long .Linfo_string3 # DW_AT_name
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.long .LStruct_decl2-.Lcu_begin0 # DW_AT_type
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.byte 9 # DW_AT_location
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.byte 3
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.quad s
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.LStruct_decl2:
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.byte 8 # Abbrev [8] 0x29:0x9 DW_TAG_structure_type
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.long .Linfo_string6 # DW_AT_name
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# DW_AT_declaration
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.byte 0 # End Of Children Mark
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.Ldebug_info_end1:
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.Lcu_begin1:
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.long .Ldebug_info_end2-.Ldebug_info_start2 # Length of Unit
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.Ldebug_info_start2:
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.short 5 # DWARF version number
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.byte 1 # DWARF Unit Type
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.byte 8 # Address Size (in bytes)
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.long .debug_abbrev # Offset Into Abbrev. Section
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.byte 5 # Abbrev [5] 0xc:0x27 DW_TAG_compile_unit
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.asciz "Hand-written DWARF" # DW_AT_producer
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.short 33 # DW_AT_language
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.LStruct_decl:
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.byte 7 # Abbrev [7] 0x29:0x9 DW_TAG_structure_type
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# DW_AT_declaration
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.quad 4878254330033667422 # DW_AT_signature
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.byte 0 # End Of Children Mark
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.Ldebug_info_end2:
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.section .debug_str,"MS",@progbits,1
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.Linfo_string3:
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.asciz "s" # string offset=60
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.Linfo_string4:
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.asciz "member" # string offset=62
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.Linfo_string5:
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.asciz "int" # string offset=69
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.Linfo_string6:
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.asciz "Struct" # string offset=73
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.section .debug_names,"",@progbits
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.long .Lnames_end0-.Lnames_start0 # Header: unit length
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.Lnames_start0:
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.short 5 # Header: version
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.short 0 # Header: padding
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.long 2 # Header: compilation unit count
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.long 1 # Header: local type unit count
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.long 0 # Header: foreign type unit count
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.long 0 # Header: bucket count
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.long 3 # Header: name count
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.long .Lnames_abbrev_end0-.Lnames_abbrev_start0 # Header: abbreviation table size
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.long 8 # Header: augmentation string size
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.ascii "LLVM0700" # Header: augmentation string
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.long .Lcu_begin0 # Compilation unit 0
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.long .Lcu_begin1 # Compilation unit 1
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.long .Ltu_begin0 # Type unit 0
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.long .Linfo_string6 # String in Bucket 0: Struct
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.long .Linfo_string3 # String in Bucket 1: s
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.long .Linfo_string5 # String in Bucket 2: int
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.long .Lnames1-.Lnames_entries0 # Offset in Bucket 0
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.long .Lnames2-.Lnames_entries0 # Offset in Bucket 1
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.long .Lnames0-.Lnames_entries0 # Offset in Bucket 2
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.Lnames_abbrev_start0:
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.byte 1 # Abbrev code
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.byte 19 # DW_TAG_structure_type
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.byte 2 # DW_IDX_type_unit
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.byte 11 # DW_FORM_data1
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.byte 3 # DW_IDX_die_offset
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.byte 19 # DW_FORM_ref4
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.byte 0 # End of abbrev
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.byte 0 # End of abbrev
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.byte 2 # Abbrev code
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.byte 52 # DW_TAG_variable
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.byte 1 # DW_IDX_compile_unit
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.byte 11 # DW_FORM_data1
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.byte 3 # DW_IDX_die_offset
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.byte 19 # DW_FORM_ref4
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.byte 0 # End of abbrev
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.byte 0 # End of abbrev
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.byte 3 # Abbrev code
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.byte 36 # DW_TAG_base_type
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.byte 2 # DW_IDX_type_unit
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.byte 11 # DW_FORM_data1
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.byte 3 # DW_IDX_die_offset
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.byte 19 # DW_FORM_ref4
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.byte 0 # End of abbrev
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.byte 0 # End of abbrev
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.byte 4 # Abbrev code
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.byte 19 # DW_TAG_structure_type
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.byte 1 # DW_IDX_compile_unit
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.byte 11 # DW_FORM_data1
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.byte 3 # DW_IDX_die_offset
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.byte 19 # DW_FORM_ref4
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.byte 0 # End of abbrev
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.byte 0 # End of abbrev
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.byte 0 # End of abbrev list
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.Lnames_abbrev_end0:
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.Lnames_entries0:
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.Lnames1:
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.byte 4 # Abbreviation code
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.byte 1 # DW_IDX_compile_unit
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.long .LStruct_decl-.Lcu_begin1 # DW_IDX_die_offset
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.byte 1 # Abbreviation code
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.byte 0 # DW_IDX_type_unit
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.long .LStruct_def-.Ltu_begin0 # DW_IDX_die_offset
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.byte 0
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# End of list: Struct
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.Lnames2:
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.byte 2 # Abbreviation code
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.byte 0 # DW_IDX_compile_unit
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.long .Ls-.Lcu_begin0 # DW_IDX_die_offset
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.byte 0
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# End of list: s
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.Lnames0:
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.byte 3 # Abbreviation code
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.byte 0 # DW_IDX_type_unit
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.long .Lint-.Ltu_begin0 # DW_IDX_die_offset
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.byte 0
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# End of list: int
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.p2align 2, 0x0
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.Lnames_end0:

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