[Bug symtab/28200] DW_AT_ranges handling in partial_die_info::read does not handle discontinuous ranges

["vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=28200

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Simon Marchi from comment #3)
> (In reply to Tom de Vries from comment #0)
> > What happens here, is that gdb puts together the address map from the
> > functions, triggered by this code in process_psymtab_comp_unit_reader being
> > called with cu_bounds_kind == PC_BOUNDS_INVALID, which sets the set_addrmap
> > argument to 1:
> > ...
> >           scan_partial_symbols (first_die, &lowpc, &highpc,
> >                                 cu_bounds_kind <= PC_BOUNDS_INVALID, cu);
> > ...
> 
> I'm trying to reproduce to understand better what you mean and I lose you
> here.  I'm at:
> 
> (top-gdb) frame
> #0  process_psymtab_comp_unit_reader (reader=0x7fffffffc3e0,
> info_ptr=0x60c000014faa "\003\004\005integer", comp_unit_die=0x621000163110,
> pretend_language=language_minimal) at
> /home/simark/src/binutils-gdb/gdb/dwarf2/read.c:6941
> 6941      if (cu_bounds_kind == PC_BOUNDS_HIGH_LOW && best_lowpc <
> best_highpc)
> 
> 
> And cu_bounds_kind is:
> 
> (top-gdb) p cu_bounds_kind
> $9 = PC_BOUNDS_RANGES
> 
> Not PC_BOUNDS_INVALID.
> 
> This is with the test case modified as you explained, with the separate but
> contiguous ranges:
> 
> 0x0000000b: DW_TAG_compile_unit
>               DW_AT_language [DW_FORM_sdata]    (2)
>               DW_AT_name [DW_FORM_string]       ("dw-ranges-psym.c")
>               DW_AT_low_pc [DW_FORM_addr]       (0x0000000000000000)
>               DW_AT_ranges [DW_FORM_sec_offset] (0x00000040
>                  [0x000000000000113e, 0x0000000000001159)
>                  [0x000000000000112b, 0x000000000000112c)
>                  [0x000000000000112c, 0x0000000000001137)
>                  [0x0000000000001137, 0x000000000000113e)
>                  [0x0000000000001124, 0x000000000000112b))

AFAIU, the "separate but contiguous ranges" maps to case II.

Indeed, in case II we expect to see PC_BOUNDS_RANGES (and the same in case I
and III).  It's only in case IV that we expect something different:
PC_BOUND_NOT_PRESENT (not PC_BOUNDS_INVALID, my mistake).

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