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comparison docs/BitCodeFormat.rst @ 121:803732b1fca8

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LLVM 5.0
author kono
date Fri, 27 Oct 2017 17:07:41 +0900
parents 1172e4bd9c6f
children 3a76565eade5
comparison
equal deleted inserted replaced
120:1172e4bd9c6f 121:803732b1fca8
548 * 16 --- `METADATA_ATTACHMENT`_ --- This contains records associating metadata 548 * 16 --- `METADATA_ATTACHMENT`_ --- This contains records associating metadata
549 with function instruction values. 549 with function instruction values.
550 550
551 * 17 --- `TYPE_BLOCK`_ --- This describes all of the types in the module. 551 * 17 --- `TYPE_BLOCK`_ --- This describes all of the types in the module.
552 552
553 * 23 --- `STRTAB_BLOCK`_ --- The bitcode file's string table.
554
553 .. _MODULE_BLOCK: 555 .. _MODULE_BLOCK:
554 556
555 MODULE_BLOCK Contents 557 MODULE_BLOCK Contents
556 --------------------- 558 ---------------------
557 559
575 ^^^^^^^^^^^^^^^^^^^^^^^^^^ 577 ^^^^^^^^^^^^^^^^^^^^^^^^^^
576 578
577 ``[VERSION, version#]`` 579 ``[VERSION, version#]``
578 580
579 The ``VERSION`` record (code 1) contains a single value indicating the format 581 The ``VERSION`` record (code 1) contains a single value indicating the format
580 version. Versions 0 and 1 are supported at this time. The difference between 582 version. Versions 0, 1 and 2 are supported at this time. The difference between
581 version 0 and 1 is in the encoding of instruction operands in 583 version 0 and 1 is in the encoding of instruction operands in
582 each `FUNCTION_BLOCK`_. 584 each `FUNCTION_BLOCK`_.
583 585
584 In version 0, each value defined by an instruction is assigned an ID 586 In version 0, each value defined by an instruction is assigned an ID
585 unique to the function. Function-level value IDs are assigned starting from 587 unique to the function. Function-level value IDs are assigned starting from
618 This can be inefficient, as operands are normally encoded 620 This can be inefficient, as operands are normally encoded
619 as unsigned VBRs. However, forward references are rare, except in the 621 as unsigned VBRs. However, forward references are rare, except in the
620 case of phi instructions. For phi instructions, operands are encoded as 622 case of phi instructions. For phi instructions, operands are encoded as
621 `Signed VBRs`_ to deal with forward references. 623 `Signed VBRs`_ to deal with forward references.
622 624
625 In version 2, the meaning of module records ``FUNCTION``, ``GLOBALVAR``,
626 ``ALIAS``, ``IFUNC`` and ``COMDAT`` change such that the first two operands
627 specify an offset and size of a string in a string table (see `STRTAB_BLOCK
628 Contents`_), the function name is removed from the ``FNENTRY`` record in the
629 value symbol table, and the top-level ``VALUE_SYMTAB_BLOCK`` may only contain
630 ``FNENTRY`` records.
623 631
624 MODULE_CODE_TRIPLE Record 632 MODULE_CODE_TRIPLE Record
625 ^^^^^^^^^^^^^^^^^^^^^^^^^ 633 ^^^^^^^^^^^^^^^^^^^^^^^^^
626 634
627 ``[TRIPLE, ...string...]`` 635 ``[TRIPLE, ...string...]``
671 for each library name referenced. 679 for each library name referenced.
672 680
673 MODULE_CODE_GLOBALVAR Record 681 MODULE_CODE_GLOBALVAR Record
674 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 682 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
675 683
676 ``[GLOBALVAR, pointer type, isconst, initid, linkage, alignment, section, visibility, threadlocal, unnamed_addr, externally_initialized, dllstorageclass, comdat]`` 684 ``[GLOBALVAR, strtab offset, strtab size, pointer type, isconst, initid, linkage, alignment, section, visibility, threadlocal, unnamed_addr, externally_initialized, dllstorageclass, comdat, attributes, preemptionspecifier]``
677 685
678 The ``GLOBALVAR`` record (code 7) marks the declaration or definition of a 686 The ``GLOBALVAR`` record (code 7) marks the declaration or definition of a
679 global variable. The operand fields are: 687 global variable. The operand fields are:
688
689 * *strtab offset*, *strtab size*: Specifies the name of the global variable.
690 See `STRTAB_BLOCK Contents`_.
680 691
681 * *pointer type*: The type index of the pointer type used to point to this 692 * *pointer type*: The type index of the pointer type used to point to this
682 global variable 693 global variable
683 694
684 * *isconst*: Non-zero if the variable is treated as constant within the module, 695 * *isconst*: Non-zero if the variable is treated as constant within the module,
748 * ``dllimport``: code 1 759 * ``dllimport``: code 1
749 * ``dllexport``: code 2 760 * ``dllexport``: code 2
750 761
751 * *comdat*: An encoding of the COMDAT of this function 762 * *comdat*: An encoding of the COMDAT of this function
752 763
764 * *attributes*: If nonzero, the 1-based index into the table of AttributeLists.
765
766 .. _bcpreemptionspecifier:
767
768 * *preemptionspecifier*: If present, an encoding of the runtime preemption specifier of this variable:
769
770 * ``dso_preemptable``: code 0
771 * ``dso_local``: code 1
772
753 .. _FUNCTION: 773 .. _FUNCTION:
754 774
755 MODULE_CODE_FUNCTION Record 775 MODULE_CODE_FUNCTION Record
756 ^^^^^^^^^^^^^^^^^^^^^^^^^^^ 776 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
757 777
758 ``[FUNCTION, type, callingconv, isproto, linkage, paramattr, alignment, section, visibility, gc, prologuedata, dllstorageclass, comdat, prefixdata, personalityfn]`` 778 ``[FUNCTION, strtab offset, strtab size, type, callingconv, isproto, linkage, paramattr, alignment, section, visibility, gc, prologuedata, dllstorageclass, comdat, prefixdata, personalityfn, preemptionspecifier]``
759 779
760 The ``FUNCTION`` record (code 8) marks the declaration or definition of a 780 The ``FUNCTION`` record (code 8) marks the declaration or definition of a
761 function. The operand fields are: 781 function. The operand fields are:
782
783 * *strtab offset*, *strtab size*: Specifies the name of the function.
784 See `STRTAB_BLOCK Contents`_.
762 785
763 * *type*: The type index of the function type describing this function 786 * *type*: The type index of the function type describing this function
764 787
765 * *callingconv*: The calling convention number: 788 * *callingconv*: The calling convention number:
766 * ``ccc``: code 0 789 * ``ccc``: code 0
812 plus 1. 835 plus 1.
813 836
814 * *personalityfn*: If non-zero, the value index of the personality function for this function, 837 * *personalityfn*: If non-zero, the value index of the personality function for this function,
815 plus 1. 838 plus 1.
816 839
840 * *preemptionspecifier*: If present, an encoding of the :ref:`runtime preemption specifier<bcpreemptionspecifier>` of this function.
841
817 MODULE_CODE_ALIAS Record 842 MODULE_CODE_ALIAS Record
818 ^^^^^^^^^^^^^^^^^^^^^^^^ 843 ^^^^^^^^^^^^^^^^^^^^^^^^
819 844
820 ``[ALIAS, alias type, aliasee val#, linkage, visibility, dllstorageclass, threadlocal, unnamed_addr]`` 845 ``[ALIAS, strtab offset, strtab size, alias type, aliasee val#, linkage, visibility, dllstorageclass, threadlocal, unnamed_addr, preemptionspecifier]``
821 846
822 The ``ALIAS`` record (code 9) marks the definition of an alias. The operand 847 The ``ALIAS`` record (code 9) marks the definition of an alias. The operand
823 fields are 848 fields are
824 849
850 * *strtab offset*, *strtab size*: Specifies the name of the alias.
851 See `STRTAB_BLOCK Contents`_.
852
825 * *alias type*: The type index of the alias 853 * *alias type*: The type index of the alias
826 854
827 * *aliasee val#*: The value index of the aliased value 855 * *aliasee val#*: The value index of the aliased value
828 856
829 * *linkage*: An encoding of the `linkage type`_ for this alias 857 * *linkage*: An encoding of the `linkage type`_ for this alias
837 :ref:`thread local property<bcthreadlocal>` of the alias 865 :ref:`thread local property<bcthreadlocal>` of the alias
838 866
839 * *unnamed_addr*: If present, an encoding of the 867 * *unnamed_addr*: If present, an encoding of the
840 :ref:`unnamed_addr<bcunnamedaddr>` attribute of this alias 868 :ref:`unnamed_addr<bcunnamedaddr>` attribute of this alias
841 869
842 MODULE_CODE_PURGEVALS Record 870 * *preemptionspecifier*: If present, an encoding of the :ref:`runtime preemption specifier<bcpreemptionspecifier>` of this alias.
843 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
844
845 ``[PURGEVALS, numvals]``
846
847 The ``PURGEVALS`` record (code 10) resets the module-level value list to the
848 size given by the single operand value. Module-level value list items are added
849 by ``GLOBALVAR``, ``FUNCTION``, and ``ALIAS`` records. After a ``PURGEVALS``
850 record is seen, new value indices will start from the given *numvals* value.
851 871
852 .. _MODULE_CODE_GCNAME: 872 .. _MODULE_CODE_GCNAME:
853 873
854 MODULE_CODE_GCNAME Record 874 MODULE_CODE_GCNAME Record
855 ^^^^^^^^^^^^^^^^^^^^^^^^^ 875 ^^^^^^^^^^^^^^^^^^^^^^^^^
1308 1328
1309 METADATA_ATTACHMENT Contents 1329 METADATA_ATTACHMENT Contents
1310 ---------------------------- 1330 ----------------------------
1311 1331
1312 The ``METADATA_ATTACHMENT`` block (id 16) ... 1332 The ``METADATA_ATTACHMENT`` block (id 16) ...
1333
1334 .. _STRTAB_BLOCK:
1335
1336 STRTAB_BLOCK Contents
1337 ---------------------
1338
1339 The ``STRTAB`` block (id 23) contains a single record (``STRTAB_BLOB``, id 1)
1340 with a single blob operand containing the bitcode file's string table.
1341
1342 Strings in the string table are not null terminated. A record's *strtab
1343 offset* and *strtab size* operands specify the byte offset and size of a
1344 string within the string table.
1345
1346 The string table is used by all preceding blocks in the bitcode file that are
1347 not succeeded by another intervening ``STRTAB`` block. Normally a bitcode
1348 file will have a single string table, but it may have more than one if it
1349 was created by binary concatenation of multiple bitcode files.