[Dwarf-discuss] "null entry"

Bishop, John E john.e.bishop
Mon May 23 16:05:19 PDT 2005


I therefore propose that this be made clearer in the
document, and make these changes

o   An index hit for "null entry", pointing to section
    7.5.2 (p 118).

o   Add some text along these lines before the second 
    paragraph in 7.5.2:

        A null entry is a debugging information entry
        whose abbreviation code is 0.  This entry has no
        attributes.

        Null entries are used for purposes such as 
        ending a list of sibling nodes.  They can also
        be used for padding because on some architectures...

I'll agree with the poster who said it was a pain to 
have zero not work as a null sibling pointer.  But there's
a work-around:

Since the value of SW_AT_sibling is a reference, and a
reference is an offset from a .debug_info section (this one
or a remote one), zero would normally mean "the first DIE".
So producers could issue a null DIE as the very first DIE,
and then zero works!  (or have I misunderstood something?)

	-John



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