[PATCH] D55261: [llvm-dwarfdump] - Simplify the test case.

[David Blaikie via Phabricator via llvm-commits]

dblaikie added inline comments.


================
Comment at: test/tools/llvm-dwarfdump/X86/no_debug_addr.s:5-6
+## When .debug_addr is absent for some reason, check we do not print a bogus section name.
+## We had a bug that could be a reason of that when
+## DW_RLE_startx_length/DW_RLE_base_addressx/DW_RLE_offset_pair tags were used.
 
----------------
grimar wrote:
> dblaikie wrote:
> > Not sure I understand this comment - but I think I get where you're going with it, might just be some grammar improvement to make it more clear?
> > 
> > Oh, actually, here's a thought - did this bug pop-up when using rnglists in .dwo files? They certainly won't have a debug_addr & would then be a fully realistic scenario rather than one where a section of debug info would have to be dropped to demonstrate the failure?
> > 
> > So maybe a comment like this:
> > 
> >   ## Ensure bogus empty section names are not printed when dumping rnglists that reference debug_addr when it is not present (such as in .dwo files).
> > 
> > Yep, looks like it does, so here's a really short example I worked up:
> > 
> >         .section        .debug_info.dwo,"e", at progbits
> >         .long   .Ldebug_info_dwo_end1-.Ldebug_info_dwo_start1   # Length of Unit
> >   .Ldebug_info_dwo_start1:
> >         .short  5                       # DWARF version number
> >         .byte   5                       # DWARF Unit Type
> >         .byte   8                       # Address Size (in bytes)
> >         .long   0                       # Offset Into Abbrev. Section
> >         .quad   -6809755978868859807
> >         .byte   1                       # Abbrev [1] 0x14:0x32 DW_TAG_compile_unit
> >         .byte   0                       # DW_AT_ranges
> >   .Ldebug_info_dwo_end1:
> >         .section        .debug_abbrev.dwo,"e", at progbits
> >         .byte   1                       # Abbreviation Code
> >         .byte   17                      # DW_TAG_compile_unit
> >         .byte   0                       # DW_CHILDREN_no
> >         .byte   85                      # DW_AT_ranges
> >         .byte   35                      # DW_FORM_rnglistx
> >         .byte   0                       # EOM(1)
> >         .byte   0                       # EOM(2)
> >         .section        .debug_rnglists.dwo,"e", at progbits
> >         .long   .Ldebug_rnglist_table_end1-.Ldebug_rnglist_table_start1 # Length
> >   .Ldebug_rnglist_table_start1:
> >         .short  5                       # Version
> >         .byte   8                       # Address size
> >         .byte   0                       # Segment selector size
> >         .long   1                       # Offset entry count
> >   .Lrnglists_dwo_table_base0:
> >         .long   .Ldebug_ranges0-.Lrnglists_dwo_table_base0
> >   .Ldebug_ranges0:
> >         .byte   1                       # DW_RLE_base_addressx
> >         .byte   0                       #   base address index
> >         .byte   4                       # DW_RLE_offset_pair
> >         .byte   0                       #   starting offset
> >         .byte   1                       #   ending offset
> >         .byte   3                       # DW_RLE_startx_length
> >         .byte   1                       #   start index
> >         .byte   2                       #   length
> >         .byte   0                       # DW_RLE_end_of_list
> >   .Ldebug_rnglist_table_end1:
> > 
> > 
> > 
> Idea about using the .dwo is interesting, thanks! I'll check it and probably update this patch tomorrow.
> 
> > Oh, actually, here's a thought - did this bug pop-up when using rnglists in .dwo files? 
> 
> I faced this in LLD actually. Its implementation of the `llvm::DWARFObject` did not override the `getRnglistsSection`
> and the effect from returning the empty section by default implementation was the same as rnglists section is absent.
Guess you meant "getAddrSection"/addr section is absent - yeah, could totally believe that - great find! & the same bug totally shows up in other places, like the dwo dumping - so handy to fix all around :)


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D55261/new/

https://reviews.llvm.org/D55261