DWARF Summary⌗

DWARF5.pdf 太长了懒得看，咱觉得看这个就够了。 实际上咱感兴趣的部分应该是 ch5: Type Entries

Just my note about DWARF5 Debugging Format Standard. Maybe focus on ch5: Type Entries

What is DWARF?⌗

DWARF is the debuginfo standard used on the majority of operating systems today.

2.1 The Debugging Information Entry (DIE) DWARF uses a series of debugging information entries (DIEs) to define a low-level representation of a source program. Each debugging information entry consists of an identifying and a series of attributes. An entry, or group of entries together, provide a description of a corresponding entity in the source program. The tag specifies the class to which an entry belongs and the attributes define the specific characteristics of the entry.

DWARF identifies and attributes⌗

  • tag : DW_TAG_<name>

  • attribute value : DW_AT_<value>

  • general operation : DW_OP_<op>

  • accessibility : DW_ACCESS_(public|private|protected)

  • visibility : DW_VIS_(local|exported|qualified)

  • virtuality : DW_VIRTUALITY_(none|virtual|pure_virtual)

  • segmented addresses : DW_ADDR_<addr>

  • for use in both split or non-split units : DW_RLE_<identifier>

  • language names (C,C99,C_plus_plus,C_plus_plus_11) : DW_LANG_<lang>

  • identifier case code : DW_ID_(case_sensitive|case_insensitive|up_case|down_case**

  • utf8? : DW_AT_use_UTF8

!!! note 同时有很多特殊的 DW_AT_xxx 懒得一一列举了， 我就枚举几个我感兴趣的吧。

  • identifier names : DW_AT_name

  • mangled names : DW_AT_linkage_name

  • template parameters : DW_TAG_template_type_parameter, DW_AT_type, DW_AT_name, DW_AT_default_value

Type Entries⌗

Base Type⌗

  • DW_TAG_base_type
  • name : string : DW_AT_name?
  • encoding : see DWARF5.pdf : DW_AT_encoding
  • endianity : { DW_END_default, DW_END_big, DW_END_little } : DW_AT_endianity? (default = the default for the target architecture)
  • value size : DW_AT_byte_size
  • DW_AT_bit_size, DA_AT_data_bit_offset (default = 0) : if value of the type does not fully occupy the value size

For example, int in C : DW_AT_name = int, DW_AT_encoding = DW_ATE_signed, DW_AT_byte_size = 4.

Unspecified Type⌗

  • DW_TAG_unspecified_type (void in C, auto in C++)
  • DW_AT_name?

Type Modifier⌗

  • DW_TAG_(atomic|const|immutable|packed|pointer|reference|restrict|rvalue_reference|shared|volatile)_type
  • DW_AT_name?
  • DW_AT_type : reference to a base type
  • DW_AT_address_class? : if pointer or reference type, describe how objects having the given pointer.
  • DW_AT_count? : if DW_TAG_shared_type (default = “infinite”), blocksize specified for the type.

Typedef⌗

  • DW_TAG_typedef
  • DW_AT_name
  • DW_AT_type : reference to the type named by the typedef.

Array Type⌗

  • DW_TAG_array_type
  • DW_AT_name
  • DW_AT_ordering? : DW_ORD_(col|row)_major (default = the default ordering for the source language)
  • DW_AT_type : the type of each element
  • (DW_AT_byte_stride | DW_AT_bit_stride)?
  • (DW_AT_byte_size | DW_AT_bit_size)? : the amount of storage needed to hold an instance of the array type.

懒得写，总之比较复杂，建议看 ch5.5: Array Type Entries

Coarray Type⌗

  • DW_TAG_coarray_type
  • DW_AT_name
  • [DW_TAG_subrange_type] : one for each codimension
  • DW_AT_type : the type of each element

In Fortran, a “coarray” is an array whose elements are located in different processes rather than in the memory of one process. The individual elements of a coarray can be scalars or arrays. Similar to arrays, coarrays have “codimensions” that are indexed using a “coindex” or multiple “coindices”.

Structure, Union, Class and Interface Type Entries⌗

Structure, Union, Class and Interface Type Entries⌗

  • DW_TAG_structure_type | DW_TAG_union_type | DW_TAG_class_type
  • DW_AT_name?
  • (DW_AT_byte_size | DW_AT_bit_size)?
  • DW_AT_declaration? : incomplete type
  • DW_AT_signature? : incomplete declaration
  • DW_AT_specification? : reference to the incomplete type
  • DW_AT_calling_convention? : indicate whether is passed by reference or value.
    • DW_CC_normal
    • DW_CC_pass_by_value
    • DW_CC_pass_by_reference

Interface Type⌗

  • DW_TAG_interface_type
  • DW_AT_name

Derived or Extended Structures, Classes and Interfaces.⌗

  • DW_TAG_inheritance
  • DW_AT_type
  • DW_AT_data_member_location
  • DW_AT_accessibility?
  • DW_AT_virtuality?

Access Declarations⌗

  • DW_TAG_access_declaration
  • DW_AT_name
  • DW_AT_accessibility

Friends⌗

  • DW_TAG_friend
  • DW_AT_friend : reference to the declaration of the friend

Data Member Entries⌗

  • DW_TAG_member
  • DW_AT_name
  • DW_AT_type
  • DW_AT_accessibility
  • DW_AT_mutable
  • (DW_AT_data_member_location | DW_AT_data_bit_offset)

Class Variable Entries⌗

  • DW_TAG_variable
  • DW_AT_accessibility

Member Function Entries⌗

  • DW_TAG_subprogram
  • DW_AT_accessibility
  • DW_AT_virtuality?
  • DW_AT_explicit?
  • DW_AT_vtable_ele_location?
  • DW_AT_object_pointer?
  • DW_AT_reference?
  • DW_AT_rvalue_reference?
  • DW_AT_specification?
  • DW_AT_deleted

Class Template Instantiations⌗

TODO

Variant Entries⌗

  • DW_TAG_variant_part
  • DW_AT_discr?
  • DW_AT_type?
  • DW_TAG_variant
  • DW_AT_discr_value
  • DW_AT_discr_list

Condition Entries⌗

  • DW_TAG_condition
  • DW_AT_name
  • DW_TAG_variable
  • DW_TAG_member | DW_TAG_formal_parameter
  • DW_TAG_constant | DW_TAG_subrange_type
  • DW_AT_type

Enum Entries⌗

  • DW_TAG_enumeration_type

Subroutine Type Entries⌗

  • DW_TAG_subroutine_type

String Type Entries⌗

  • DW_TAG_string_type

Set Type Entries⌗

  • DW_TAG_set_type

Subrange Type Entries⌗

  • DW_TAG_subrange_type

Pointer to Member Type Entries⌗

  • DW_TAG_ptr_to_member_type

File Type Entries⌗

  • DW_TAG_file_type

Dynamic Type Entries⌗

  • DW_TAG_dynamic_type

Template Alias Entries⌗

  • DW_TAG_template_alias

Dynamic Properties of Types⌗

  • DW_TAG_dynamic_type
  • DW_AT_(data_location|allocated|associated)