Consider test-case gdb.dwarf2/imported-unit.exp.
It contains a CU with type int:
...
<0><129>: Abbrev Number: 2 (DW_TAG_compile_unit)
<12a> DW_AT_language : 4 (C++)
<12b> DW_AT_name : imported_unit.c
<1><13b>: Abbrev Number: 3 (DW_TAG_base_type)
<13c> DW_AT_byte_size : 4
<13d> DW_AT_encoding : 5 (signed)
<13e> DW_AT_name : int
...
which is imported in another CU:
...
<0><d2>: Abbrev Number: 2 (DW_TAG_compile_unit)
<d3> DW_AT_language : 4 (C++)
<d4> DW_AT_name : <artificial>
<1><e1>: Abbrev Number: 3 (DW_TAG_imported_unit)
<e2> DW_AT_import : <0x129> [Abbrev Number: 2]
...
However, if we print the partial symbols:
...
$ gdb -batch imported-unit -ex "maint print psymbols"
...
we see type int both in the importing CU:
...
Partial symtab for source file <artificial>@0xc7 (object 0x29f9b80)
...
Depends on 1 other partial symtabs.
0 0x2a24240 imported_unit.c
Global partial symbols:
`main', function, 0x4004b2
Static partial symbols:
`int', type, 0x0
...
and in the imported CU:
...
Partial symtab for source file imported_unit.c (object 0x2a24240)
...
Depends on 0 other partial symtabs.
Shared partial symtab with user 0x29f9b80
Static partial symbols:
`int', type, 0x0
...
This is an artefact resulting from the fact that all CUs in an objfile
share the same storage array for static partial symbols (and another array for
global partial symbols), using a range to describe their symbols.
Then when scanning the partial symbols of a CU and encountering an import, either:
- the referred CU has not been parsed yet, and will be parsed, and the range of
static partial symbols of the referred CU will be a subrange of the range of
static partial symbols of this CU, or
- the referred CU has already been parsed, and the range of static partial
symbols of the referred CU will not be a subrange of the range of static
partial symbols of this CU.
This is inconsistent handling, and confuses the notion of a symbol belonging to
a single symtab.
Furthermore, it might slow down searches, given that the symbol needs to be
skipped twice.
Finally, the same issue holds for global partial symbols, where the range of a
CU is sorted after parsing is finished. Obviously sorting the range of a CU
may invalidate subranges, effectively moving symbols in and out of imported
CUs.
Fix this for both static and global partial symbols, by gathering partial
symbols in a per-CU vector, and adding those symbols to the per-objfile
storage only once complete.
Tested on x86_64-linux, with native and board cc-with-dwz and cc-with-dwz-m.
gdb/ChangeLog:
2020-03-13 Tom de Vries <tdevries@suse.de>
PR symtab/25646
* psymtab.c (partial_symtab::partial_symtab): Don't set
globals_offset and statics_offset. Push element onto
current_global_psymbols and current_static_psymbols stacks.
(concat): New function.
(end_psymtab_common): Set globals_offset and statics_offset. Pop
element from current_global_psymbols and current_static_psymbols
stacks. Concat popped elements to global_psymbols and
static_symbols.
(add_psymbol_to_list): Use current_global_psymbols and
current_static_psymbols stacks.
* psymtab.h (class psymtab_storage): Add current_global_psymbols and
current_static_psymbols fields.
gdb/testsuite/ChangeLog:
2020-03-13 Tom de Vries <tdevries@suse.de>
PR symtab/25646
* gdb.dwarf2/imported-unit.exp: Add test.
When running the gdb testsuite with the cc-with-dwz board, I run into:
...
Running gdb/testsuite/gdb.dwarf2/imported-unit.exp ...
gdb compile failed, dwz: gdb.dwarf2/imported-unit/imported-unit: \
Couldn't find DIE referenced by DW_AT_abstract_origin
cc-with-tweaks.sh: dwz did not modify gdb.dwarf2/imported-unit/imported-unit.
...
The problem is that the DW_AT_abstract_origin reference here:
...
<0><d2>: Abbrev Number: 2 (DW_TAG_compile_unit)
<1><e6>: Abbrev Number: 4 (DW_TAG_subprogram)
<e7> DW_AT_abstract_origin: <0x142>
<eb> DW_AT_low_pc : 0x4004b2
<f3> DW_AT_high_pc : 0x4004c8
...
referring to a DIE in another compilation unit here:
...
<0><129>: Abbrev Number: 2 (DW_TAG_compile_unit)
<1><142>: Abbrev Number: 4 (DW_TAG_subprogram)
<143> DW_AT_name : main
<148> DW_AT_type : <0x13b>
<14c> DW_AT_external : 1
...
is encoded using intra-CU reference form DW_FORM_ref4 instead of intra-CU
reference DW_FORM_ref_addr:
...
4 DW_TAG_subprogram [has children]
DW_AT_abstract_origin DW_FORM_ref4
DW_AT_low_pc DW_FORM_addr
DW_AT_high_pc DW_FORM_addr
DW_AT value: 0 DW_FORM value: 0
...
Fix this in the DWARF assembler by making all inter-CU references use the '%'
label prefix.
Tested on x86_64-linux.
gdb/testsuite/ChangeLog:
2019-12-08 Tom de Vries <tdevries@suse.de>
* gdb.dwarf2/imported-unit.exp: Fix inter-CU references.
Change-Id: I690ff18c3943705ed478453531b176ff74700f3c
Running a GDB with the fix for BZ 25065 should cause these new tests
to all pass.
When run against a GDB without the fix, there will be 2 unresolved
testcases. This is what I see in the gdb.sum file when I try it using
a GDB without the fix:
ERROR: GDB process no longer exists
UNRESOLVED: gdb.dwarf2/imported-unit.exp: ptype main::Foo
ERROR: Couldn't send ptype main::foo to GDB.
UNRESOLVED: gdb.dwarf2/imported-unit.exp: ptype main::foo
These are "unresolved" versus outright failures due to the fact that
GDB dies (segfaults) during the running of the test.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/imported-unit.exp: New file.
* gdb.dwarf2/imported-unit.c: New file.
Change-Id: I073fe69b81bd258951615f752df8e95b6e33a271
Tom de Vries
Joel Brobecker
Kevin Buettner