[gdb/symtab] Handle DW_AT_decl_file with form DW_FORM_implicit_const
authorTom de Vries <tdevries@suse.de>
Wed, 24 Feb 2021 22:58:42 +0000 (23:58 +0100)
committerTom de Vries <tdevries@suse.de>
Wed, 24 Feb 2021 22:58:42 +0000 (23:58 +0100)
commitaa659cfad638376ab535bc5a7b65c164327e9e21
tree5b0b06a659dfcaa6c02c9cf12003687abb7b4915
parent268c77c1b0cc5d82c894af6e3e4f040c1bd4644e
[gdb/symtab] Handle DW_AT_decl_file with form DW_FORM_implicit_const

With test-case gdb.cp/temargs.exp on target board \
unix/gdb:debug_flags=-gdwarf-5 I run into:
...
(gdb) info addr I^M
ERROR: GDB process no longer exists
GDB process exited with wait status 32286 exp19 0 0 CHILDKILLED SIGABRT SIGABRT
UNRESOLVED: gdb.cp/temargs.exp: test address of I in templ_m
...

This is a regression since commit 529908cbd0a "Remove DW_UNSND".

The problem is that this DW_AT_decl_file:
...
 <1><221>: Abbrev Number: 4 (DW_TAG_structure_type)
    <222>   DW_AT_name        : Base<double, 23, (& a_global), &S::f>
    <226>   DW_AT_byte_size   : 1
    <226>   DW_AT_decl_file   : 1
    <226>   DW_AT_decl_line   : 30
    <227>   DW_AT_sibling     : <0x299>
...
is not read by this code in new_symbol:
....
      attr = dwarf2_attr (die,
                          inlined_func ? DW_AT_call_file : DW_AT_decl_file,
                          cu);
      if (attr != nullptr && attr->form_is_unsigned ())
...
because DW_AT_decl_file has form DW_FORM_implicit_const:
...
   4      DW_TAG_structure_type    [has children]
    DW_AT_name         DW_FORM_strp
    DW_AT_byte_size    DW_FORM_implicit_const: 1
    DW_AT_decl_file    DW_FORM_implicit_const: 1
    DW_AT_decl_line    DW_FORM_data1
    DW_AT_sibling      DW_FORM_ref4
    DW_AT value: 0     DW_FORM value: 0
...
which is a signed LEB128, so attr->form_is_unsigned () returns false.

Fix this by introducing new functions is_nonnegative and as_nonnegative, and
use these instead of form_is_unsigned and as_unsigned.

Tested on x86_64-linux.

gdb/ChangeLog:

2021-02-24  Tom de Vries  <tdevries@suse.de>

PR symtab/27336
* dwarf2/attribute.c (attribute::form_is_signed): New function
factored out of ...
* dwarf2/attribute.h (attribute::as_signed): ... here.
(attribute::is_nonnegative, attribute::as_nonnegative): New function.
(attribute::form_is_signed): Declare.
* dwarf2/read.c (new_symbol): Use is_nonnegative and as_nonnegative
for DW_AT_decl_file.
gdb/ChangeLog
gdb/dwarf2/attribute.c
gdb/dwarf2/attribute.h
gdb/dwarf2/read.c