A while ago, back when GDB was a C program, the sect_offset and
cu_offset types were made structs in order to prevent incorrect mixing
of those offsets. Now that we require C++11, we can make them
integers again, while keeping the safety, by exploiting "enum class".
We can add a bit more safety, even, by defining operators that the
types _should_ support, helping making the suspicious uses stand out
more.
Getting at the underlying type is done with the new to_underlying
function added by the previous patch, which also helps better spot
where do we need to step out of the safety net. Mostly, that's around
parsing the DWARF, and when we print the offset for complaint/debug
purposes. But there are other occasional uses.
Since we have to define the sect_offset/cu_offset types in a header
anyway, I went ahead and generalized/library-fied the idea of "offset"
types, making it trivial to add more such types if we find a use. See
common/offset-type.h and the DEFINE_OFFSET_TYPE macro.
I needed a couple generaly-useful preprocessor bits (e.g., yet another
CONCAT implementation), so I started a new common/preprocessor.h file.
I included units tests covering the "offset" types API. These are
mostly compile-time tests, using SFINAE to check that expressions that
shouldn't compile (e.g., comparing unrelated offset types) really are
invalid and would fail to compile. This same idea appeared in my
pending enum-flags revamp from a few months ago (though this version
is a bit further modernized compared to what I had posted), and I plan
on reusing the "check valid expression" bits added here in that
series, so I went ahead and defined the CHECK_VALID_EXPR macro in its
own header -- common/valid-expr.h. I think that's nicer regardless.
I was borderline between calling the new types "offset" types, or
"index" types, BTW. I stuck with "offset" simply because that's what
we're already calling them, mostly.
gdb/ChangeLog:
2017-04-04 Pedro Alves <palves@redhat.com>
* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
unittests/offset-type-selftests.c.
(SUBDIR_UNITTESTS_OBS): Add offset-type-selftests.o.
* common/offset-type.h: New file.
* common/preprocessor.h: New file.
* common/traits.h: New file.
* common/valid-expr.h: New file.
* dwarf2expr.c: Include "common/underlying.h". Adjust to use
sect_offset and cu_offset strong typedefs throughout.
* dwarf2expr.h: Adjust to use sect_offset and cu_offset strong
typedefs throughout.
* dwarf2loc.c: Include "common/underlying.h". Adjust to use
sect_offset and cu_offset strong typedefs throughout.
* dwarf2read.c: Adjust to use sect_offset and cu_offset strong
typedefs throughout.
* gdbtypes.h: Include "common/offset-type.h".
(cu_offset): Now an offset type (strong typedef) instead of a
struct.
(sect_offset): Likewise.
(union call_site_parameter_u): Rename "param_offset" field to
"param_cu_off".
* unittests/offset-type-selftests.c: New file.
Recently I fixed a bug that caused a DW_OP_implicit_pointer with non-zero
offset into a DW_OP_implicit_value to be handled incorrectly on big-endian
targets. GDB ignored the offset and copied the wrong bytes:
https://sourceware.org/ml/gdb-patches/2017-01/msg00251.html
But there is still a similar issue when a DW_OP_implicit_pointer points
into a DW_OP_stack_value instead; and again, the offset is ignored. There
is an important difference, though: While implicit values are treated like
blocks of data and anchored at the lowest-addressed byte, stack values
traditionally contain integer numbers and are anchored at the *least
significant* byte. Also, stack values do not come in varying sizes, but
are cut down appropriately when used. Thus, on big-endian targets the
scenario looks like this (higher addresses shown right):
|<- - - - - Stack value - - - - - - ->|
| |
|<- original object ->|
|
| offset ->|####|
^^^^
de-referenced
implicit pointer
(Note how the original object's size influences the position of the
de-referenced implicit pointer within the stack value. This is not the
case for little-endian targets, where the original object starts at offset
zero within the stack value.)
This patch implements the logic indicated in the above diagram and adds an
appropriate test case. A new function dwarf2_fetch_die_type_sect_off is
added; it is used for retrieving the original object's type, so its size
can be determined. That type is passed to dwarf2_evaluate_loc_desc_full
via a new parameter.
gdb/ChangeLog:
* dwarf2loc.c (indirect_synthetic_pointer): Get data type of
pointed-to DIE and pass it to dwarf2_evaluate_loc_desc_full.
(dwarf2_evaluate_loc_desc_full): New parameter subobj_type; rename
byte_offset to subobj_byte_offset. Fix the handling of
DWARF_VALUE_STACK on big-endian targets when coming via an
implicit pointer.
(dwarf2_evaluate_loc_desc): Adjust call to
dwarf2_evaluate_loc_desc_full.
* dwarf2loc.h (dwarf2_fetch_die_type_sect_off): New declaration.
* dwarf2read.c (dwarf2_fetch_die_type_sect_off): New function.
gdb/testsuite/ChangeLog:
* lib/dwarf.exp: Add support for DW_OP_implicit_pointer.
* gdb.dwarf2/nonvar-access.exp: Add test for stack value location
and implicit pointer into such a location.
This patch starts from the desire to eliminate
make_cleanup_ui_file_delete, but then goes beyond. It makes ui_file &
friends a real C++ class hierarchy, and switches temporary
ui_file-like objects to stack-based allocation.
- mem_fileopen -> string_file
mem_fileopen is replaced with a new string_file class that is treated
as a value class created on the stack. This alone eliminates most
make_cleanup_ui_file_delete calls, and, simplifies code a whole lot
(diffstat shows around 1k loc dropped.)
string_file's internal buffer is a std::string, thus the "string" in
the name. This simplifies the implementation much, compared to
mem_fileopen, which managed growing its internal buffer manually.
- ui_file_as_string, ui_file_strdup, ui_file_obsavestring all gone
The new string_file class has a string() method that provides direct
writable access to the internal std::string buffer. This replaced
ui_file_as_string, which forced a copy of the same data the stream had
inside. With direct access via a writable reference, we can instead
move the string out of the string_stream, avoiding deep string
copying.
Related, ui_file_xstrdup calls are replaced with xstrdup'ping the
stream's string, and ui_file_obsavestring is replaced by
obstack_copy0.
With all those out of the way, getting rid of the weird ui_file_put
mechanism was possible.
- New ui_file::printf, ui_file::puts, etc. methods
These simplify / clarify client code. I considered splitting
client-code changes, like these, e.g.:
- stb = mem_fileopen ();
- fprintf_unfiltered (stb, "%s%s%s",
- _("The valid values are:\n"),
- regdesc,
- _("The default is \"std\"."));
+ string_file stb;
+ stb.printf ("%s%s%s",
+ _("The valid values are:\n"),
+ regdesc,
+ _("The default is \"std\"."));
In two steps, with the first step leaving fprintf_unfiltered (etc.)
calls in place, and only afterwards do a pass to change all those to
call stb.printf etc.. I didn't do that split, because (when I tried),
it turned out to be pointless make-work: the first pass would have to
touch the fprintf_unfiltered line anyway, to replace "stb" with
"&stb".
- gdb_fopen replaced with stack-based objects
This avoids the need for cleanups or unique_ptr's. I.e., this:
struct ui_file *file = gdb_fopen (filename, "w");
if (filename == NULL)
perror_with_name (filename);
cleanups = make_cleanup_ui_file_delete (file);
// use file.
do_cleanups (cleanups);
is replaced with this:
stdio_file file;
if (!file.open (filename, "w"))
perror_with_name (filename);
// use file.
- odd contorsions in null_file_write / null_file_fputs around when to
call to_fputs / to_write eliminated.
- Global null_stream object
A few places that were allocating a ui_file in order to print to
"nowhere" are adjusted to instead refer to a new 'null_stream' global
stream.
- TUI's tui_sfileopen eliminated. TUI's ui_file much simplified
The TUI's ui_file was serving a dual purpose. It supported being used
as string buffer, and supported being backed by a stdio FILE. The
string buffer part is gone, replaced by using of string_file. The
'FILE *' support is now much simplified, by making the TUI's ui_file
inherit from stdio_file.
gdb/ChangeLog:
2017-02-02 Pedro Alves <palves@redhat.com>
* ada-lang.c (type_as_string): Use string_file.
* ada-valprint.c (ada_print_floating): Use string_file.
* ada-varobj.c (ada_varobj_scalar_image)
(ada_varobj_get_value_image): Use string_file.
* aix-thread.c (aix_thread_extra_thread_info): Use string_file.
* arm-tdep.c (_initialize_arm_tdep): Use string_printf.
* breakpoint.c (update_inserted_breakpoint_locations)
(insert_breakpoint_locations, reattach_breakpoints)
(print_breakpoint_location, print_one_detail_ranged_breakpoint)
(print_it_watchpoint): Use string_file.
(save_breakpoints): Use stdio_file.
* c-exp.y (oper): Use string_file.
* cli/cli-logging.c (set_logging_redirect): Use ui_file_up and
tee_file.
(pop_output_files): Use delete.
(handle_redirections): Use stdio_file and tee_file.
* cli/cli-setshow.c (do_show_command): Use string_file.
* compile/compile-c-support.c (c_compute_program): Use
string_file.
* compile/compile-c-symbols.c (generate_vla_size): Take a
'string_file &' instead of a 'ui_file *'.
(generate_c_for_for_one_variable): Take a 'string_file &' instead
of a 'ui_file *'. Use string_file.
(generate_c_for_variable_locations): Take a 'string_file &'
instead of a 'ui_file *'.
* compile/compile-internal.h (generate_c_for_for_one_variable):
Take a 'string_file &' instead of a 'ui_file *'.
* compile/compile-loc2c.c (push, pushf, unary, binary)
(print_label, pushf_register_address, pushf_register)
(do_compile_dwarf_expr_to_c): Take a 'string_file &' instead of a
'ui_file *'. Adjust.
* compile/compile.c (compile_to_object): Use string_file.
* compile/compile.h (compile_dwarf_expr_to_c)
(compile_dwarf_bounds_to_c): Take a 'string_file &' instead of a
'ui_file *'.
* cp-support.c (inspect_type): Use string_file and obstack_copy0.
(replace_typedefs_qualified_name): Use string_file and
obstack_copy0.
* disasm.c (gdb_pretty_print_insn): Use string_file.
(gdb_disassembly): Adjust reference the null_stream global.
(do_ui_file_delete): Delete.
(gdb_insn_length): Use null_stream.
* dummy-frame.c (maintenance_print_dummy_frames): Use stdio_file.
* dwarf2loc.c (dwarf2_compile_property_to_c)
(locexpr_generate_c_location, loclist_generate_c_location): Take a
'string_file &' instead of a 'ui_file *'.
* dwarf2loc.h (dwarf2_compile_property_to_c): Likewise.
* dwarf2read.c (do_ui_file_peek_last): Delete.
(dwarf2_compute_name): Use string_file.
* event-top.c (gdb_setup_readline): Use stdio_file.
* gdbarch.sh (verify_gdbarch): Use string_file.
* gdbtypes.c (safe_parse_type): Use null_stream.
* guile/scm-breakpoint.c (gdbscm_breakpoint_commands): Use
string_file.
* guile/scm-disasm.c (gdbscm_print_insn_from_port): Take a
'string_file *' instead of a 'ui_file *'.
(gdbscm_arch_disassemble): Use string_file.
* guile/scm-frame.c (frscm_print_frame_smob): Use string_file.
* guile/scm-ports.c (class ioscm_file_port): Now a class that
inherits from ui_file.
(ioscm_file_port_delete, ioscm_file_port_rewind)
(ioscm_file_port_put): Delete.
(ioscm_file_port_write): Rename to ...
(ioscm_file_port::write): ... this. Remove file_port_magic
checks.
(ioscm_file_port_new): Delete.
(ioscm_with_output_to_port_worker): Use ioscm_file_port and
ui_file_up.
* guile/scm-type.c (tyscm_type_name): Use string_file.
* guile/scm-value.c (vlscm_print_value_smob, gdbscm_value_print):
Use string_file.
* infcmd.c (print_return_value_1): Use string_file.
* infrun.c (print_target_wait_results): Use string_file.
* language.c (add_language): Use string_file.
* location.c (explicit_to_string_internal): Use string_file.
* main.c (captured_main_1): Use null_file.
* maint.c (maintenance_print_architecture): Use stdio_file.
* mi/mi-cmd-stack.c (list_arg_or_local): Use string_file.
* mi/mi-common.h (struct mi_interp) <out, err, log, targ,
event_channel>: Change type to mi_console_file pointer.
* mi/mi-console.c (mi_console_file_fputs, mi_console_file_flush)
(mi_console_file_delete): Delete.
(struct mi_console_file): Delete.
(mi_console_file_magic): Delete.
(mi_console_file_new): Delete.
(mi_console_file::mi_console_file): New.
(mi_console_file_delete): Delete.
(mi_console_file_fputs): Delete.
(mi_console_file::write): New.
(mi_console_raw_packet): Delete.
(mi_console_file::flush): New.
(mi_console_file_flush): Delete.
(mi_console_set_raw): Rename to ...
(mi_console_file::set_raw): ... this.
* mi/mi-console.h (class mi_console_file): New class.
(mi_console_file_new, mi_console_set_raw): Delete.
* mi/mi-interp.c (mi_interpreter_init): Use mi_console_file.
(mi_set_logging): Use delete and tee_file. Adjust.
* mi/mi-main.c (output_register): Use string_file.
(mi_cmd_data_evaluate_expression): Use string_file.
(mi_cmd_data_read_memory): Use string_file.
(mi_cmd_execute, print_variable_or_computed): Use string_file.
* mi/mi-out.c (mi_ui_out::main_stream): New.
(mi_ui_out::rewind): Use main_stream and
string_file.
(mi_ui_out::put): Use main_stream and string_file.
(mi_ui_out::mi_ui_out): Remove 'stream' parameter.
Allocate a 'string_file' instead.
(mi_out_new): Don't allocate a mem_fileopen stream here.
* mi/mi-out.h (mi_ui_out::mi_ui_out): Remove 'stream' parameter.
(mi_ui_out::main_stream): Declare method.
* printcmd.c (eval_command): Use string_file.
* psymtab.c (maintenance_print_psymbols): Use stdio_file.
* python/py-arch.c (archpy_disassemble): Use string_file.
* python/py-breakpoint.c (bppy_get_commands): Use string_file.
* python/py-frame.c (frapy_str): Use string_file.
* python/py-framefilter.c (py_print_type, py_print_single_arg):
Use string_file.
* python/py-type.c (typy_str): Use string_file.
* python/py-unwind.c (unwind_infopy_str): Use string_file.
* python/py-value.c (valpy_str): Use string_file.
* record-btrace.c (btrace_insn_history): Use string_file.
* regcache.c (regcache_print): Use stdio_file.
* reggroups.c (maintenance_print_reggroups): Use stdio_file.
* remote.c (escape_buffer): Use string_file.
* rust-lang.c (rust_get_disr_info): Use string_file.
* serial.c (serial_open_ops_1): Use stdio_file.
(do_serial_close): Use delete.
* stack.c (print_frame_arg): Use string_file.
(print_frame_args): Remove local mem_fileopen stream, not used.
(print_frame): Use string_file.
* symmisc.c (maintenance_print_symbols): Use stdio_file.
* symtab.h (struct symbol_computed_ops) <generate_c_location>:
Take a 'string_file *' instead of a 'ui_file *'.
* top.c (new_ui): Use stdio_file and stderr_file.
(free_ui): Use delete.
(execute_command_to_string): Use string_file.
(quit_confirm): Use string_file.
* tracepoint.c (collection_list::append_exp): Use string_file.
* tui/tui-disasm.c (tui_disassemble): Use string_file.
* tui/tui-file.c: Don't include "ui-file.h".
(enum streamtype, struct tui_stream): Delete.
(tui_file_new, tui_file_delete, tui_fileopen, tui_sfileopen)
(tui_file_isatty, tui_file_rewind, tui_file_put): Delete.
(tui_file::tui_file): New method.
(tui_file_fputs): Delete.
(tui_file_get_strbuf): Delete.
(tui_file::puts): New method.
(tui_file_adjust_strbuf): Delete.
(tui_file_flush): Delete.
(tui_file::flush): New method.
* tui/tui-file.h: Tweak intro comment.
Include ui-file.h.
(tui_fileopen, tui_sfileopen, tui_file_get_strbuf)
(tui_file_adjust_strbuf): Delete declarations.
(class tui_file): New class.
* tui/tui-io.c (tui_initialize_io): Use tui_file.
* tui/tui-regs.c (tui_restore_gdbout): Use delete.
(tui_register_format): Use string_stream.
* tui/tui-stack.c (tui_make_status_line): Use string_file.
(tui_get_function_from_frame): Use string_file.
* typeprint.c (type_to_string): Use string_file.
* ui-file.c (struct ui_file, ui_file_magic, ui_file_new): Delete.
(null_stream): New global.
(ui_file_delete): Delete.
(ui_file::ui_file): New.
(null_file_isatty): Delete.
(ui_file::~ui_file): New.
(null_file_rewind): Delete.
(ui_file::printf): New.
(null_file_put): Delete.
(null_file_flush): Delete.
(ui_file::putstr): New.
(null_file_write): Delete.
(ui_file::putstrn): New.
(null_file_read): Delete.
(ui_file::putc): New.
(null_file_fputs): Delete.
(null_file_write_async_safe): Delete.
(ui_file::vprintf): New.
(null_file_delete): Delete.
(null_file::write): New.
(null_file_fseek): Delete.
(null_file::puts): New.
(ui_file_data): Delete.
(null_file::write_async_safe): New.
(gdb_flush, ui_file_isatty): Adjust.
(ui_file_put, ui_file_rewind): Delete.
(ui_file_write): Adjust.
(ui_file_write_for_put): Delete.
(ui_file_write_async_safe, ui_file_read): Adjust.
(ui_file_fseek): Delete.
(fputs_unfiltered): Adjust.
(set_ui_file_flush, set_ui_file_isatty, set_ui_file_rewind)
(set_ui_file_put, set_ui_file_write, set_ui_file_write_async_safe)
(set_ui_file_read, set_ui_file_fputs, set_ui_file_fseek)
(set_ui_file_data): Delete.
(string_file::~string_file, string_file::write)
(struct accumulated_ui_file, do_ui_file_xstrdup, ui_file_xstrdup)
(do_ui_file_as_string, ui_file_as_string): Delete.
(do_ui_file_obsavestring, ui_file_obsavestring): Delete.
(struct mem_file): Delete.
(mem_file_new): Delete.
(stdio_file::stdio_file): New.
(mem_file_delete): Delete.
(stdio_file::stdio_file): New.
(mem_fileopen): Delete.
(stdio_file::~stdio_file): New.
(mem_file_rewind): Delete.
(stdio_file::set_stream): New.
(mem_file_put): Delete.
(stdio_file::open): New.
(mem_file_write): Delete.
(stdio_file_magic, struct stdio_file): Delete.
(stdio_file_new, stdio_file_delete, stdio_file_flush): Delete.
(stdio_file::flush): New.
(stdio_file_read): Rename to ...
(stdio_file::read): ... this. Adjust.
(stdio_file_write): Rename to ...
(stdio_file::write): ... this. Adjust.
(stdio_file_write_async_safe): Rename to ...
(stdio_file::write_async_safe) ... this. Adjust.
(stdio_file_fputs): Rename to ...
(stdio_file::puts) ... this. Adjust.
(stdio_file_isatty): Delete.
(stdio_file_fseek): Delete.
(stdio_file::isatty): New.
(stderr_file_write): Rename to ...
(stderr_file::write) ... this. Adjust.
(stderr_file_fputs): Rename to ...
(stderr_file::puts) ... this. Adjust.
(stderr_fileopen, stdio_fileopen, gdb_fopen): Delete.
(stderr_file::stderr_file): New.
(tee_file_magic): Delete.
(struct tee_file): Delete.
(tee_file::tee_file): New.
(tee_file_new): Delete.
(tee_file::~tee_file): New.
(tee_file_delete): Delete.
(tee_file_flush): Rename to ...
(tee_file::flush): ... this. Adjust.
(tee_file_write): Rename to ...
(tee_file::write): ... this. Adjust.
(tee_file::write_async_safe): New.
(tee_file_fputs): Rename to ...
(tee_file::puts): ... this. Adjust.
(tee_file_isatty): Rename to ...
(tee_file::isatty): ... this. Adjust.
* ui-file.h (struct obstack, struct ui_file): Don't
forward-declare.
(ui_file_new, ui_file_flush_ftype, set_ui_file_flush)
(ui_file_write_ftype)
(set_ui_file_write, ui_file_fputs_ftype, set_ui_file_fputs)
(ui_file_write_async_safe_ftype, set_ui_file_write_async_safe)
(ui_file_read_ftype, set_ui_file_read, ui_file_isatty_ftype)
(set_ui_file_isatty, ui_file_rewind_ftype, set_ui_file_rewind)
(ui_file_put_method_ftype, ui_file_put_ftype, set_ui_file_put)
(ui_file_delete_ftype, set_ui_file_data, ui_file_fseek_ftype)
(set_ui_file_fseek): Delete.
(ui_file_data, ui_file_delete, ui_file_rewind)
(struct ui_file): New.
(ui_file_up): New.
(class null_file): New.
(null_stream): Declare.
(ui_file_write_for_put, ui_file_put): Delete.
(ui_file_xstrdup, ui_file_as_string, ui_file_obsavestring):
Delete.
(ui_file_fseek, mem_fileopen, stdio_fileopen, stderr_fileopen)
(gdb_fopen, tee_file_new): Delete.
(struct string_file): New.
(struct stdio_file): New.
(stdio_file_up): New.
(struct stderr_file): New.
(class tee_file): New.
* ui-out.c (ui_out::field_stream): Take a 'string_file &' instead
of a 'ui_file *'. Adjust.
* ui-out.h (class ui_out) <field_stream>: Likewise.
* utils.c (do_ui_file_delete, make_cleanup_ui_file_delete)
(null_stream): Delete.
(error_stream): Take a 'string_file &' instead of a 'ui_file *'.
Adjust.
* utils.h (struct ui_file): Delete forward declaration..
(make_cleanup_ui_file_delete, null_stream): Delete declarations.
(error_stream): Take a 'string_file &' instead of a
'ui_file *'.
* varobj.c (varobj_value_get_print_value): Use string_file.
* xtensa-tdep.c (xtensa_verify_config): Use string_file.
* gdbarch.c: Regenerate.
When a variable's location is expressed as DW_OP_implicit_value, but the
given value is longer than needed, which bytes should be used? GDB's
current logic was introduced with a patch from 2011 and uses the "least
significant" bytes:
https://sourceware.org/ml/gdb-patches/2011-08/msg00123.html
Now consider a sub-value from such a location at a given offset, accessed
through DW_OP_implicit_pointer. Which bytes should be used for that? The
patch above *always* uses the last bytes on big-endian targets, ignoring
the offset.
E.g., given the code snippet
const char foo[] = "Hello, world!";
const char *a = &foo[0];
const char *b = &foo[7];
assume that `foo' is described as DW_OP_implicit_value and `a' and `b'
each as DW_OP_implicit_pointer into that value. Then with current GDB
`*a' and `*b' yield the same result -- the string's zero terminator.
This patch basically reverts the portion of the patch above that deals
with DW_OP_implicit_value. This fixes the offset handling and also goes
back to dropping the last instead of the first bytes on big-endian targets
if the implicit value is longer than needed. The latter aspect of the
change probably doesn't matter for actual programs, but simplifies the
logic.
The patch also cleans up the original code a bit and adds appropriate test
cases.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/dw2-op-stack-value.exp: Adjust expected result of
taking a 2-byte value out of a 4-byte DWARF implicit value on
big-endian targets.
* gdb.dwarf2/nonvar-access.exp: Add more comments to existing
logic. Add test cases for DW_OP_implicit.
gdb/ChangeLog:
* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): For
DWARF_VALUE_LITERAL, no longer ignore the offset on big-endian
targets. And if the implicit value is longer than needed, extract
the first bytes instead of the "least significant" ones.
This changes dwarf2_evaluate_loc_desc_full to use scoped_value_mark.
Note that this function previously called do_cleanup using the same
cleanup multiple times. I had thought this was buggy, but re-reading
make_my_cleanup2 indicates that it is not. Nevertheless it is
surprising, and at least one of the calls (the one that is completely
removed in this patch) seems to have been done under the assumption
that it would still have some effect.
2017-01-10 Tom Tromey <tom@tromey.com>
* value.h (scoped_value_mark::~scoped_value_mark): Call
free_to_mark.
(scoped_value_mark::free_to_mark): New method.
* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Use
scoped_value_mark.
This adds a scoped_value_mark class, that records the value mark in
the constructor and then calls value_free_to_mark in the destructor.
It then updates various spots in gdb to use this class, rather than a
cleanup.
It would be better overall to replace "struct value *" with a
shared_ptr, maybe eliminating the need for this class (watchpoints
would perhaps need some new mechanism as well). However, that's
difficult to do.
2017-01-10 Tom Tromey <tom@tromey.com>
* python/py-value.c (valpy_dereference, valpy_referenced_value)
(valpy_reference_value, valpy_const_value, valpy_get_address)
(valpy_get_dynamic_type, valpy_lazy_string, valpy_do_cast)
(valpy_getitem, valpy_call, valpy_binop_throw, valpy_negative)
(valpy_absolute, valpy_richcompare_throw): Use scoped_value_mark.
* dwarf2loc.c (dwarf2_loc_desc_get_symbol_read_needs): Use
scoped_value_mark.
* dwarf2-frame.c (execute_stack_op): Use scoped_value_mark.
* value.h (scoped_value_mark): New class.
This removes make_cleanup_htab_delete in favor of destructors,
building on an earlier patch that added the htab_up typedef.
Testing revealed that more cleanup-removal work was needed in
dwarf2loc.c, so this version of the patch changes code there to use
unordered_set and vector, removing some more cleanups.
2017-01-10 Tom Tromey <tom@tromey.com>
* utils.h (make_cleanup_htab_delete): Don't declare.
* utils.c (do_htab_delete_cleanup, make_cleanup_htab_delete):
Remove.
* linespec.c (decode_compound_collector): Add constructor,
destructor.
(lookup_prefix_sym): Remove cleanup.
(symtab_collector): Add constructor, destructor.
(collect_symtabs_from_filename): Remove cleanup.
* disasm.c (do_mixed_source_and_assembly): Use htab_up.
* compile/compile-c-symbols.c (generate_c_for_variable_locations):
Use htab_up.
* gnu-v3-abi.c (gnuv3_print_vtable): Use htab_up.
* dwarf2read.c (dw2_expand_symtabs_matching)
(dw2_map_symbol_filenames, dwarf_decode_macros)
(write_psymtabs_to_index): Use htab_up.
* dwarf2loc.c (func_verify_no_selftailcall)
(call_site_find_chain_1, func_verify_no_selftailcall)
(chain_candidate, call_site_find_chain_1): Use std::unordered_set,
std::vector, gdb::unique_xmalloc_ptr.
(call_sitep): Remove typedef.
(dwarf2_locexpr_baton_eval): Remove unused variable.
In ee40d8d (Move computed value's frame id to piece_closure), I only
updated read_pieced_value to use frame_id from piece_closure, but
forgot to update write_pieced_value, so it causes the following
internal error on arm-linux,
set variable l = 4^M
gdb/git/gdb/value.c:1579: internal-error: frame_id* deprecated_value_next_frame_id_hack(value*): Assertion `value->lval == lval_register' failed.^M
A problem internal to GDB has been detected,^M
further debugging may prove unreliable.^M
Quit this debugging session? (y or n) FAIL: gdb.base/store.exp: var longest l; setting l to 4 (GDB internal error)
This patch fixes the internal error.
gdb:
2017-01-04 Yao Qi <yao.qi@linaro.org>
* dwarf2loc.c (write_pieced_value): Don't use VALUE_FRAME_ID (to),
use c->frame_id when the piece location is DWARF_VALUE_REGISTER.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
Nowadays, we set computed value's frame id, which is a misuse to me.
The computed value itself doesn't care about frame id, but function
value_computed_funcs (val)->read (or read_pieced_value) cares about
which frame the register is relative to, so 'struct piece_closure' is
a better place to fit frame id.
This patch adds a frame id in 'struct piece_closure', and use it
instead of using computed value's frame id.
gdb:
2016-11-28 Yao Qi <yao.qi@linaro.org>
* dwarf2loc.c (struct piece_closure) <frame_id>: New field.
(allocate_piece_closure): Add new parameter 'frame' and set
closure's frame_id field accordingly.
(read_pieced_value): Get frame from closure instead of value.
(dwarf2_evaluate_loc_desc_full): Remove code getting frame id.
Don't set value's frame id.
The function copy_bitwise used for copying DWARF pieces can potentially
be invoked for large chunks of data. For instance, consider a large
struct one of whose members is currently located in a register. In this
case copy_bitwise would still copy the data bitwise in a loop, which is
much slower than necessary.
This change uses memcpy for the large part instead, if possible.
gdb/ChangeLog:
* dwarf2loc.c (copy_bitwise): Use memcpy for the middle part, if
it is byte-aligned.
This adds a unit test for the copy_bitwise function in dwarf2loc.c.
With the old (broken) version of copy_bitwise this test would generate
the following failure message:
(gdb) maintenance selftest
Self test failed: copy_bitwise 11000000 != 10000000 (7+2 -> 0)
gdb/ChangeLog:
2016-11-24 Andreas Arnez <arnez@linux.vnet.ibm.com>
Pedro Alves <palves@redhat.com>
* dwarf2loc.c (bits_to_str, check_copy_bitwise)
(copy_bitwise_tests): New functions.
(_initialize_dwarf2loc): Register the new function
copy_bitwise_tests as a unit test.
* selftest.c (run_self_tests): Improve the failure message's
wording and formatting.
When the user writes or reads a variable whose location is described
with DWARF pieces (DW_OP_piece or DW_OP_bit_piece), GDB's helper
function copy_bitwise is invoked for each piece. The implementation of
this function has a bug that may result in a corrupted copy, depending
on alignment and bit size. (Full-byte copies are not affected.)
This rewrites copy_bitwise, replacing its algorithm by a fixed version,
and adding an appropriate test case. Without the fix the new test case
fails, e.g.:
print def_t
$2 = {a = 0, b = 4177919}
(gdb) FAIL: gdb.dwarf2/nonvar-access.exp: print def_t
Written in binary, the wrong result above looks like this:
01111111011111111111111
Which means that two zero bits have sneaked into the copy of the
original all-one bit pattern. The test uses this simple all-one value
in order to avoid another GDB bug that causes the DWARF piece of a
DW_OP_stack_value to be taken from the wrong end on big-endian
architectures.
gdb/ChangeLog:
* dwarf2loc.c (extract_bits_primitive): Remove.
(extract_bits): Remove.
(copy_bitwise): Rewrite. Fixes a possible corruption that may
occur for non-byte-aligned copies.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/nonvar-access.exp: Add a test for accessing
non-byte-aligned bit fields.
The VALUE_FRAME_ID macro provides access to a member in struct value
that's used to hold the frame id that's used when determining a
register's value or when assigning to a register. The underlying
member has a long and obscure name. I won't refer to it here, but
will simply refer to VALUE_FRAME_ID as if it's the struct value member
instead of being a convenient macro.
At the moment, without this patch in place, VALUE_FRAME_ID is set in
value_of_register_lazy() and several other locations to hold the frame
id of the frame passed to those functions.
VALUE_FRAME_ID is used in the lval_register case of
value_fetch_lazy(). To fetch the register's value, it calls
get_frame_register_value() which, in turn, calls
frame_unwind_register_value() with frame->next.
A python based unwinder may wish to determine the value of a register
or evaluate an expression containing a register. When it does this,
value_fetch_lazy() will be called under some circumstances. It will
attempt to determine the frame id associated with the frame passed to
it. In so doing, it will end up back in the frame sniffer of the very
same python unwinder that's attempting to learn the value of a
register as part of the sniffing operation. This recursion is not
desirable.
As noted above, when value_fetch_lazy() wants to fetch a register's
value, it does so (indirectly) by unwinding from frame->next.
With this in mind, a solution suggests itself: Change VALUE_FRAME_ID
to hold the frame id associated with the next frame. Then, when it
comes time to obtain the value associated with the register, we can
simply unwind from the frame corresponding to the frame id stored in
VALUE_FRAME_ID. This neatly avoids the python unwinder recursion
problem by changing when the "next" operation occurs. Instead of the
"next" operation occuring when the register value is fetched, it
occurs earlier on when assigning a frame id to VALUE_FRAME_ID.
(Thanks to Pedro for this suggestion.)
This patch implements this idea.
It builds on the patch "Distinguish sentinel frame from null frame".
Without that work in place, it's necessary to check for null_id at
several places and then obtain the sentinel frame.
It also renames most occurences of VALUE_FRAME_ID to
VALUE_NEXT_FRAME_ID to reflect the new meaning of this field.
There are several uses of VALUE_FRAME_ID which were not changed. In
each case, the original meaning of VALUE_FRAME_ID is required to get
correct results. In all but one of these uses, either
put_frame_register_bytes() or get_frame_register_bytes() is being
called with the frame value obtained from VALUE_FRAME_ID. Both of
these functions perform some unwinding by performing a "->next"
operation on the frame passed to it. If we were to use the new
VALUE_NEXT_FRAME_ID macro, this would effectively do two "->next"
operations, which is not what we want.
The VALUE_FRAME_ID macro has been redefined in terms of
VALUE_NEXT_FRAME_ID. It simply fetches the previous frame's id,
providing this id as the value of the macro.
gdb/ChangeLog:
* value.h (VALUE_FRAME_ID): Rename to VALUE_NEXT_FRAME_ID. Update
comment. Create new VALUE_FRAME_ID which is defined in terms of
VALUE_NEXT_FRAME_ID.
(deprecated_value_frame_id_hack): Rename to
deprecated_value_next_frame_id_hack.
* dwarf2loc.c, findvar.c, frame-unwind.c, sentinel-frame.c,
valarith.c, valops.c, value.c: Adjust nearly all occurences of
VALUE_FRAME_ID to VALUE_NEXT_FRAME_ID. Add comments for those
which did not change.
* value.c (struct value): Rename frame_id field to next_frame_id.
Update comment.
(deprecated_value_frame_id_hack): Rename to
deprecated_value_next_frame_id_hack.
(value_fetch_lazy): Call frame_unwind_register_value()
instead of get_frame_register_value().
* frame.c (get_prev_frame_id_by_id): New function.
* frame.h (get_prev_frame_id_by_id): Declare.
* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Make
VALUE_NEXT_FRAME_ID refer to the next frame.
* findvar.c (value_of_register_lazy): Likewise.
(default_value_from_register): Likewise.
(value_from_register): Likewise.
* frame_unwind.c (frame_unwind_got_optimized): Likewise.
* sentinel-frame.c (sentinel_frame_prev_register): Likewise.
* value.h (VALUE_FRAME_ID): Update comment describing this macro.
This fixes some regressions found in the patch to convert
dwarf_expr_context to use methods. Specifically:
* get_base_type could erroneously throw; this was rewritten to move
the size checks into the only spot needing them.
* Previously the "symbol needs frame" implementation reused th
"cfa" function for the get_frame_pc slot; this reimplements
it under the correct name.
* Not enough members were saved and restored in one implementation
of push_dwarf_reg_entry_value; this patch fixes this oversight
and also takes the opportunity to remove an extraneous structure
definition.
2016-11-02 Tom Tromey <tom@tromey.com>
* dwarf2loc.c (dwarf_evaluate_loc_desc::get_base_type): Rename
from impl_get_base_type. Rewrite.
(struct dwarf_expr_baton): Remove.
(dwarf_evaluate_loc_desc::push_dwarf_reg_entry_value): Save and
restore more fields.
(symbol_needs_eval_context::get_frame_pc): New method.
* dwarf2expr.h (dwarf_expr_context::get_base_type): Now public,
virtual.
(dwarf_expr_context::impl_get_base_type): Remove.
* dwarf2expr.c (dwarf_expr_context::get_base_type): Remove.
This patch converts the function pointers in dwarf_expr_context_funcs
into methods on dwarf_expr_context, and then updates the various
implementations and callers to follow.
NB this patch uses "override" (which caught a couple of renaming bugs
during development) -- but this is C++11, so this patch at least has
to wait for Pedro's patch that adds the OVERRIDE macro.
After this patch it would be possible to do one more, that makes
various members of dwarf_expr_context "protected"; but I haven't done
this.
2016-10-21 Tom Tromey <tom@tromey.com>
* dwarf2loc.c (struct dwarf_expr_context_funcs): Don't declare.
(dwarf_expr_read_addr_from_reg, dwarf_expr_get_reg_value)
(dwarf_expr_read_mem, dwarf_expr_frame_base): Rename; turn into
methods.
(get_frame_pc_for_per_cu_dwarf_call): New function.
(dwarf_expr_frame_cfa, dwarf_expr_frame_pc)
(dwarf_expr_tls_address): Rename; turn into methods.
(per_cu_dwarf_call): Remove arguments. Use
get_frame_pc_for_per_cu_dwarf_call.
(dwarf_evaluate_loc_desc): New class.
(dwarf_expr_dwarf_call, dwarf_expr_context)
(dwarf_expr_push_dwarf_reg_entry_value)
(dwarf_expr_get_addr_index, dwarf_expr_get_obj_addr): Rename; turn
into methods.
(dwarf_expr_ctx_funcs): Remove.
(dwarf2_evaluate_loc_desc_full): Update.
(dwarf2_locexpr_baton_eval): Update.
(symbol_needs_eval_context): New class.
(symbol_needs_read_addr_from_reg, symbol_needs_get_reg_value)
(symbol_needs_read_mem, symbol_needs_frame_base)
(symbol_needs_frame_cfa, symbol_needs_tls_address)
(symbol_needs_dwarf_call, needs_dwarf_reg_entry_value): Rename;
turn into methods.
(needs_get_addr_index, needs_get_obj_addr): Remove; turn into
methods.
(symbol_needs_ctx_funcs): Remove.
(dwarf2_loc_desc_get_symbol_read_needs): Update.
* dwarf2expr.h (struct dwarf_expr_context_funcs): Remove; turn
contents into methods.
(struct dwarf_expr_context) <baton, funcs>: Remove.
<read_addr_from_reg, get_reg_value, read_mem, get_frame_base,
get_frame_cfa, get_frame_pc, get_tls_address, dwarf_call,
impl_get_base_type, push_dwarf_block_entry_value, get_addr_index,
get_object_address>: Declare new methods.
(ctx_no_get_frame_base, ctx_no_get_frame_cfa)
(ctx_no_get_frame_pc, ctx_no_get_tls_address, ctx_no_dwarf_call)
(ctx_no_get_base_type, ctx_no_push_dwarf_reg_entry_value)
(ctx_no_get_addr_index): Don't declare.
* dwarf2expr.c (get_base_type): Use impl_get_base_type.
(execute_stack_op): Update.
(ctx_no_get_frame_base, ctx_no_get_frame_cfa)
(ctx_no_get_frame_pc, ctx_no_get_tls_address, ctx_no_dwarf_call)
(ctx_no_get_base_type, ctx_no_push_dwarf_reg_entry_value)
(ctx_no_get_addr_index): Remove; now methods on
dwarf_expr_context.
* dwarf2-frame.c (read_addr_from_reg): Take a frame_info, not a
baton.
(class dwarf_expr_executor): New class.
(get_reg_value, read_mem): Rename, turn into methods.
(execute_stack_op): Use dwarf_expr_executor.
This converts various DWARF expr functions to be members on
dwarf_expr_context, then fixes up the various users. This results in
somewhat less wordy code and sets the stage for the next patch.
2016-10-21 Tom Tromey <tom@tromey.com>
* dwarf2loc.c (per_cu_dwarf_call)
(dwarf_expr_push_dwarf_reg_entry_value)
(dwarf2_evaluate_loc_desc_full, dwarf2_locexpr_baton_eval)
(needs_dwarf_reg_entry_value)
(dwarf2_loc_desc_get_symbol_read_needs): Update.
* dwarf2expr.h (dwarf_expr_context) <push_address, eval, fetch,
fetch_address, fetch_in_stack_memory, address_type, grow_stack,
push, stack_empty_p, add_piece, get_base_type, execute_stack_op,
pop>: New method declarations.
(dwarf_expr_push_address, dwarf_expr_eval, dwarf_expr_fetch)
(dwarf_expr_fetch_address, dwarf_expr_fetch_in_stack_memory):
Don't declare.
* dwarf2expr.c (address_type, grow_stack, push, push_address)
(pop, fetch, fetch_address, fetch_in_stack_memory)
(stack_empty_p, add_piece, eval, get_base_type)
(execute_stack_op): Rename. Turn into methods.
* dwarf2-frame.c (execute_stack_op): Update.
This is the first step in the conversion of dwarf_expr_ctx to a C++
class. This conversion is done in steps to make the patches, and the
reviews, a bit simpler. This patch changes dwarf_expr_ctx to be
stack-allocated and removes the associated cleanup.
2016-10-21 Tom Tromey <tom@tromey.com>
* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Stack-allocate
dwarf_expr_context. Remove cleanups.
(dwarf2_locexpr_baton_eval)
(dwarf2_loc_desc_get_symbol_read_needs): Likewise.
* dwarf2expr.h (dwarf_expr_context, ~dwarf_expr_context): Add
constructors and destructors.
(new_dwarf_expr_context, free_dwarf_expr_context)
(make_cleanup_free_dwarf_expr_context): Don't declare.
* dwarf2-frame.c (execute_stack_op): Stack-allocate
dwarf_expr_context. Remove cleanups.
(dwarf_expr_context): Rename from new_dwarf_expr_context. Turn
into constructor.
(free_dwarf_expr_context, free_dwarf_expr_context_cleanup):
Remove.
(~dwarf_expr_context): Rename from
make_cleanup_free_dwarf_expr_context. Turn into destructor.
This removes some cleanups and manual allocation handling in
dwarf2loc.c with std::vector. Note that this patch has a case where
the vector would normally fall into the "use gdb::unique_ptr"
guidelines -- but here because the vector is immediately initialized,
I moved the initialization into the constructor call, for further
code savings.
2016-10-21 Tom Tromey <tom@tromey.com>
* dwarf2loc.c: Include <vector>.
(read_pieced_value, write_pieced_value)
(dwarf2_compile_expr_to_ax): Use std::vector.
Currently gdb supports DW_OP_GNU_push_tls_address, but not
DW_OP_form_tls_address. I think it would be better if the toolchain
as a whole moved to using the standard opcode, and the prerequisite to
this is getting gdb to recognize it.
GCC can sometimes emit DW_OP_form_tls_address for emultls targets. As
far as I know, nobody has ever tried this with gdb (since it wouldn't
work at all).
I don't think there's a major drawback to using a single opcode for
all targets, because computing the location of a thread-local is
already target specific.
This is PR gdb/11616.
I don't know how to write a test case for this; though it's worth
noting that there aren't explicit tests for DW_OP_GNU_push_tls_address
either -- and if I change GCC, these paths will be tested to the same
extent they are now.
2016-09-02 Tom Tromey <tom@tromey.com>
PR gdb/11616:
* dwarf2read.c (decode_locdesc): Handle DW_OP_form_tls_address.
* dwarf2loc.c (dwarf2_compile_expr_to_ax): Handle
DW_OP_form_tls_address.
(locexpr_describe_location_piece): Likewise.
* dwarf2expr.h (struct dwarf_expr_context_funcs): Update comment.
* dwarf2expr.c (execute_stack_op): Handle DW_OP_form_tls_address.
(ctx_no_get_tls_address): Mention DW_OP_form_tls_address.
* compile/compile-loc2c.c (struct insn_info): Update comment.
(compute_stack_depth_worker): Handle DW_OP_form_tls_address.
PR python/20190 arose from an exception I noticed when trying to use
the Python unwinder for Spider Monkey in Firefox.
The problem is that the unwinder wants to examine the value of a
thread-local variable. However, sympy_value rejects this because
symbol_read_needs_frame returns true for a TLS variable.
This problem arose once before, though in a different context:
https://sourceware.org/bugzilla/show_bug.cgi?id=11803
At the time Pedro and Daniel pointed out a simpler way to fix that bug
(see links in 20190 if you are interested); but for this new bug I
couldn't think of a similar fix and ended up implementing Daniel's
other suggestion:
https://sourceware.org/ml/gdb-patches/2010-07/msg00393.html
That is, this patch makes it possible to detect whether a symbol needs
a specific frame, or whether it just needs the inferior to have
registers.
Built and regtested on x86-64 Fedora 24.
2016-07-26 Tom Tromey <tom@tromey.com>
* symtab.c (register_symbol_computed_impl): Update.
PR python/20190:
* value.h (symbol_read_needs): Declare.
(symbol_read_needs_frame): Add comment.
* symtab.h (struct symbol_computed_ops) <read_variable>: Update
comment.
<get_symbol_read_needs>: Rename. Change return type.
* findvar.c (symbol_read_needs): New function.
(symbol_read_needs_frame): Rewrite.
(default_read_var_value): Use symbol_read_needs.
* dwarf2loc.c (struct symbol_needs_baton): Rename.
<needs>: Renamed from needs_frame. Changed type.
(needs_frame_read_addr_from_reg, symbol_needs_get_reg_value)
(symbol_needs_read_mem, symbol_needs_frame_base)
(symbol_needs_frame_cfa, symbol_needs_tls_address)
(symbol_needs_dwarf_call): Rename.
(needs_dwarf_reg_entry_value): Update.
(symbol_needs_ctx_funcs, dwarf2_loc_desc_get_symbol_read_needs):
Rename and update.
(locexpr_get_symbol_read_needs, loclist_symbol_needs): Likewise.
(dwarf2_locexpr_funcs, dwarf2_loclist_funcs): Update.
* defs.h (enum symbol_needs_kind): New.
2016-07-26 Tom Tromey <tom@tromey.com>
PR python/20190:
* gdb.threads/tls.exp (check_thread_local): Add python symbol
test.
GDB computes structure byte offsets using a 32 bit integer. And,
first it computes the offset in bits and then converts to bytes. The
result is that any offset that if 512K bytes or larger overflows.
This patch changes GDB to use LONGEST for such calculations.
PR gdb/17520 Structure offset wrong when 1/4 GB or greater.
* c-lang.h: Change all parameters, variables, and struct or union
members used as struct or union fie3ld offsets from int to
LONGEST.
* c-valprint.c: Likewise.
* cp-abi.c: Likewise.
* cp-abi.h: Likewise.
* cp-valprint.c: Likewise.
* d-valprint.c: Likewise.
* dwarf2loc.c: Likewise.
* eval.c: Likewise.
* extension-priv.h: Likewise.
* extension.c: Likewise.
* extension.h: Likewise.
* findvar.c: Likewise.
* gdbtypes.h: Likewise.
* gnu-v2-abi.c: Likewise.
* gnu-v3-abi.c: Likewise.
* go-valprint.c: Likewise.
* guile/guile-internal.h: Likewise.
* guile/scm-pretty-print.c: Likewise.
* jv-valprint.c Likewise.
* opencl-lang.c: Likewise.
* p-lang.h: Likewise.
* python/py-prettyprint.c: Likewise.
* python/python-internal.h: Likewise.
* spu-tdep.c: Likewise.
* typeprint.c: Likewise.
* valarith.c: Likewise.
* valops.c: Likewise.
* valprint.c: Likewise.
* valprint.h: Likewise.
* value.c: Likewise.
* value.h: Likewise.
* p-valprint.c: Likewise.
* c-typeprint.c (c_type_print_base): When printing offset, use
plongest, not %d.
* gdbtypes.c (recursive_dump_type): Ditto.
https://sourceware.org/bugzilla/show_bug.cgi?id=19893
I've traced the main source of the problem to pieced_value_funcs.coerce_ref not being
implemented. Since gdb always assumes references are implemented as pointers, this
causes it to think that it's dealing with a NULL pointer, thus breaking any operations
involving synthetic references.
What I did here was implementing pieced_value_funcs.coerce_ref using some of the synthetic
pointer handling code from indirect_pieced_value, as Pedro suggested. I also made a few
adjustments to the reference printing code so that it correctly shows either the address
of the referenced value or (if it's non-addressable) the "<synthetic pointer>" string.
I also wrote some unit tests based on Dwarf::assemble; these took a while to make
because in most cases I needed a synthetic reference to a physical variable. Additionally,
I started working on a unit test for classes that have a vtable, but ran into a few issues
so that'll probably go in a future patch. One thing that should definitely be fixed is that
proc function_range (called for MACRO_AT_func) will always try to compile/link using gcc
with the default options instead of g++, thus breaking C++ compilations that require e.g. libstdc++.
gdb/ChangeLog:
* dwarf2loc.c (coerce_pieced_ref, indirect_synthetic_pointer,
fetch_const_value_from_synthetic_pointer): New functions.
(indirect_pieced_value): Move lower half to indirect_synthetic_pointer.
(pieced_value_funcs): Implement coerce_ref.
* valops.c (value_addr): Call coerce_ref for synthetic references.
* valprint.c (valprint_check_validity): Return true for synthetic
references. Also, don't show "<synthetic pointer>" if they reference
addressable values.
(generic_val_print_ref): Handle synthetic references. Also move some
code to print_ref_address.
(print_ref_address, get_value_addr_contents): New functions.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/implref.exp: Rename to...
* gdb.dwarf2/implref-const.exp: ...this. Also add more test statements.
* gdb.dwarf2/implref-array.c: New file.
* gdb.dwarf2/implref-array.exp: Likewise.
* gdb.dwarf2/implref-global.c: Likewise.
* gdb.dwarf2/implref-global.exp: Likewise.
* gdb.dwarf2/implref-struct.c: Likewise.
* gdb.dwarf2/implref-struct.exp: Likewise.
gdb/ChangeLog:
* dwarf2loc.c (dwarf2_find_location_expression): For DWO files still
add base_offset.
gdb/testsuite/ChangeLog:
* lib/dwarf.exp (build_executable_from_fission_assembler): Pass
$options when building executable.
* gdb.dwarf2/fission-loclists-pie.c: New file.
* gdb.dwarf2/fission-loclists-pie.exp: New file.
This patch fixes the following failures for rl78-elf:
FAIL: gdb.base/vla-datatypes.exp: print int_vla
FAIL: gdb.base/vla-datatypes.exp: print unsigned_int_vla
FAIL: gdb.base/vla-datatypes.exp: print double_vla
FAIL: gdb.base/vla-datatypes.exp: print float_vla
FAIL: gdb.base/vla-datatypes.exp: print long_vla
FAIL: gdb.base/vla-datatypes.exp: print unsigned_long_vla
FAIL: gdb.base/vla-datatypes.exp: print char_vla
FAIL: gdb.base/vla-datatypes.exp: print short_vla
FAIL: gdb.base/vla-datatypes.exp: print unsigned_short_vla
FAIL: gdb.base/vla-datatypes.exp: print unsigned_char_vla
FAIL: gdb.base/vla-datatypes.exp: print foo_vla
FAIL: gdb.base/vla-datatypes.exp: print bar_vla
FAIL: gdb.base/vla-datatypes.exp: print vla_struct_object
FAIL: gdb.base/vla-datatypes.exp: print vla_union_object
FAIL: gdb.base/vla-ptr.exp: print td_vla
FAIL: gdb.mi/mi-vla-c99.exp: evaluate complete vla
The first failure in this bunch occurs due to printing an incorrect
result for a variable length array:
print int_vla
$1 = {-1, -1, -1, -1, -1}
The result should actually be this:
$1 = {0, 2, 4, 6, 8}
When I started examining this bug, I found that printing an
individual array element worked correctly. E.g. "print int_vla[2]"
resulted in 4 being printed. I have not looked closely to see why
this is the case.
I found that evaluation of the location expression for int_vla was
causing problems. This is the relevant DWARF entry for int_vla:
<2><15a>: Abbrev Number: 10 (DW_TAG_variable)
<15b> DW_AT_name : (indirect string, offset: 0xbf): int_vla
<15f> DW_AT_decl_file : 1
<160> DW_AT_decl_line : 35
<161> DW_AT_type : <0x393>
<165> DW_AT_location : 4 byte block: 86 7a 94 2 (DW_OP_breg22 (r22): -6; DW_OP_deref_size: 2)
I found that DW_OP_breg22 was providing a correct result.
DW_OP_deref_size was fetching the correct value from memory. However,
the value being fetched should be considered a pointer.
DW_OP_deref_size zero extends the fetched value prior to pushing
it onto the evaluation stack. (The DWARF-4 document specifies this
action; so GDB is faithfully implementing the DWARF-4 specification.)
However, zero extending the pointer is not sufficient for converting
that value to an address for rl78 and (perhaps) other architectures
which define a `pointer_to_address' method. (I suspect that m32c
would have the same problem.)
Ideally, we would perform the pointer to address conversion in
DW_OP_deref_size. We don't, however, know the type of the object
that the address refers to in DW_OP_deref_size. I can't think
of a way to infer the type at that point in the code.
Before proceeding, I should note that there are two other DWARF
operations that could be used in place of DW_OP_deref_size. One of
these is DW_OP_GNU_deref_type. Current GDB implements this operation,
but as is obvious from the name, it is non-standard DWARF. The other
operation is DW_OP_xderef_size. Even though it's part of DWARF-2
through DWARF-4 specifications, it's not presently implemented in GDB.
Present day GCC does not output dwarf expressions containing this
operation either. [Of the two, I like DW_OP_GNU_deref_type better.
Using it avoids the need to specify an "address space identifier".
(GCC, GDB, and other non-free tools all need to agree on the meanings
of these identifiers.)]
Back to the bug analysis...
The closest consumer of the DW_OP_deref_size result is the
DWARF_VALUE_MEMORY case in dwarf2_evaluate_loc_desc_full. At that
location, we do know the object type to which the address is intended
to refer. I added code to perform a pointer to address conversion at
this location. (See the patch.)
I do have some misgivings regarding this patch. As noted earlier, it
would really be better to perform the pointer to address conversion in
DW_OP_deref_size. I can't, however, think of a way to make this work.
Changing GCC to output one of the other aforementioned operations might
be preferable but, as noted earlier, these solutions have problems as
well. Long term, I think it'd be good to have something like
DW_OP_GNU_deref_type become part of the standard. If that can't or
won't happen, we'll need to implement DW_OP_xderef_size.
But until that happens, this patch will work for expressions in which
DW_OP_deref_size occurs last. It should even work for dereferences
followed by adding an offset. I don't think it'll work for more than
one dereference in the same expression.
gdb/ChangeLog:
* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Perform a pointer
to address conversion for DWARF_VALUE_MEMORY.
We have noticed that GDB would sometimes crash trying to print
from a nested function the value of a variable declared in an
enclosing scope. This appears to be target dependent, although
that correlation might only be fortuitious. We noticed the issue
on x86_64-darwin, x86-vxworks6 and x86-solaris. The investigation
was done on Darwin.
This is a new feature that was introduced by:
commit 63e43d3aed
Date: Thu Feb 5 17:00:06 2015 +0100
DWARF: handle non-local references in nested functions
We can reproduce the problem with one of the testcases that was
added with the patch (gdb.base/nested-subp1.exp), where we have...
18 int
19 foo (int i1)
20 {
21 int
22 nested (int i2)
23 {
[...]
27 return i1 * i2; /* STOP */
28 }
... After building the example program, and running until line 27,
try printing the value of "i1":
% gdb gdb.base/nested-subp1
(gdb) break foo.c:27
(gdb) run
Breakpoint 1, nested (i2=2) at /[...]/nested-subp1.c:27
27 return i1 * i2; /* STOP */
(gdb) p i1
[1] 73090 segmentation fault ../gdb -q gdb.base/nested-subp1
Ooops!
What happens is that, because the reference is non-local, we are trying
to follow the function's static link, which does...
/* If we don't know how to compute FRAME's base address, don't give up:
maybe the frame we are looking for is upper in the stace frame. */
if (framefunc != NULL
&& SYMBOL_BLOCK_OPS (framefunc)->get_frame_base != NULL
&& (SYMBOL_BLOCK_OPS (framefunc)->get_frame_base (framefunc, frame)
== upper_frame_base))
... or, in other words, calls the get_frame_base "method" of
framefunc's struct symbol_block_ops data. This resolves to
the block_op_get_frame_base function.
Looking at the function's implementation, we see:
struct dwarf2_locexpr_baton *dlbaton;
[...]
dlbaton = SYMBOL_LOCATION_BATON (framefunc);
[...]
result = dwarf2_evaluate_loc_desc (type, frame, start, length,
dlbaton->per_cu);
^^^^^^^^^^^^^^^
Printing dlbaton->per_cu gives a value that seems fairly bogus for
a memory address (0x60). Because of it, dwarf2_evaluate_loc_desc
then crashes trying to dereference it.
What's different on Darwin compared to Linux is that the function's
frame base is encoded using the following form:
.byte 0x40 # uleb128 0x40; (DW_AT_frame_base)
.byte 0x6 # uleb128 0x6; (DW_FORM_data4)
... and so dwarf2_symbol_mark_computed ends up creating
a SYMBOL_LOCATION_BATON as a struct dwarf2_loclist_baton:
if (attr_form_is_section_offset (attr)
/* .debug_loc{,.dwo} may not exist at all, or the offset may be outside
the section. If so, fall through to the complaint in the
other branch. */
&& DW_UNSND (attr) < dwarf2_section_size (objfile, section))
{
struct dwarf2_loclist_baton *baton;
[...]
SYMBOL_LOCATION_BATON (sym) = baton;
However, if you look more closely at block_op_get_frame_base's
implementation, you'll notice that the function extracts the
symbol's SYMBOL_LOCATION_BATON as a dwarf2_locexpr_baton
(a DWARF _expression_ rather than a _location list_).
That's why we end up decoding the DLBATON improperly, and thus
pass a random dlbaton->per_cu when calling dwarf2_evaluate_loc_desc.
This works on x86_64-linux, because we indeed have the frame base
described using a different form:
.uleb128 0x40 # (DW_AT_frame_base)
.uleb128 0x18 # (DW_FORM_exprloc)
This patch fixes the issue by doing what we do for most (if not all)
other such methods: providing one implementation each for loc-list,
and loc-expr. Both implementations are nearly identical, so perhaps
we might later want to improve this. But this patch first tries to
fix the crash first, leaving the design issue for later.
gdb/ChangeLog:
* dwarf2loc.c (locexpr_get_frame_base): Renames
block_op_get_frame_base.
(dwarf2_block_frame_base_locexpr_funcs): Replace reference to
block_op_get_frame_base by reference to locexpr_get_frame_base.
(loclist_get_frame_base): New function, near identical copy of
locexpr_get_frame_base.
(dwarf2_block_frame_base_loclist_funcs): Replace reference to
block_op_get_frame_base by reference to loclist_get_frame_base.
Tested on x86_64-darwin (AdaCore testsuite), and x86_64-linux
(official testsuite).
GDB's current behavior when dealing with non-local references in the
context of nested fuctions is approximative:
- code using valops.c:value_of_variable read the first available stack
frame that holds the corresponding variable (whereas there can be
multiple candidates for this);
- code directly relying on read_var_value will instead read non-local
variables in frames where they are not even defined.
This change adds the necessary context to symbol reads (to get the block
they belong to) and to blocks (the static link property, if any) so that
GDB can make the proper decisions when dealing with non-local varibale
references.
gdb/ChangeLog:
* ada-lang.c (ada_read_var_value): Add a var_block argument
and pass it to default_read_var_value.
* block.c (block_static_link): New accessor.
* block.h (block_static_link): Declare it.
* buildsym.c (finish_block_internal): Add a static_link
argument. If there is a static link, associate it to the new
block.
(finish_block): Add a static link argument and pass it to
finish_block_internal.
(end_symtab_get_static_block): Update calls to finish_block and
to finish_block_internal.
(end_symtab_with_blockvector): Update call to
finish_block_internal.
* buildsym.h: Forward-declare struct dynamic_prop.
(struct context_stack): Add a static_link field.
(finish_block): Add a static link argument.
* c-exp.y: Remove an obsolete comment (evaluation of variables
already start from the selected frame, and now they climb *up*
the call stack) and propagate the block information to the
produced expression.
* d-exp.y: Likewise.
* f-exp.y: Likewise.
* go-exp.y: Likewise.
* jv-exp.y: Likewise.
* m2-exp.y: Likewise.
* p-exp.y: Likewise.
* coffread.c (coff_symtab_read): Update calls to finish_block.
* dbxread.c (process_one_symbol): Likewise.
* xcoffread.c (read_xcoff_symtab): Likewise.
* compile/compile-c-symbols.c (convert_one_symbol): Promote the
"sym" parameter to struct block_symbol, update its uses and pass
its block to calls to read_var_value.
(convert_symbol_sym): Update the calls to convert_one_symbol.
* compile/compile-loc2c.c (do_compile_dwarf_expr_to_c): Update
call to read_var_value.
* dwarf2loc.c (block_op_get_frame_base): New.
(dwarf2_block_frame_base_locexpr_funcs): Implement the
get_frame_base method.
(dwarf2_block_frame_base_loclist_funcs): Likewise.
(dwarf2locexpr_baton_eval): Add a frame argument and use it
instead of the selected frame in order to evaluate the
expression.
(dwarf2_evaluate_property): Add a frame argument. Update call
to dwarf2_locexpr_baton_eval to provide a frame in available and
to handle the absence of address stack.
* dwarf2loc.h (dwarf2_evaluate_property): Add a frame argument.
* dwarf2read.c (attr_to_dynamic_prop): Add a forward
declaration.
(read_func_scope): Record any available static link description.
Update call to finish_block.
(read_lexical_block_scope): Update call to finish_block.
* findvar.c (follow_static_link): New.
(get_hosting_frame): New.
(default_read_var_value): Add a var_block argument. Use
get_hosting_frame to handle non-local references.
(read_var_value): Add a var_block argument and pass it to the
LA_READ_VAR_VALUE method.
* gdbtypes.c (resolve_dynamic_range): Update calls to
dwarf2_evaluate_property.
(resolve_dynamic_type_internal): Likewise.
* guile/scm-frame.c (gdbscm_frame_read_var): Update call to
read_var_value, passing it the block coming from symbol lookup.
* guile/scm-symbol.c (gdbscm_symbol_value): Update call to
read_var_value (TODO).
* infcmd.c (finish_command_continuation): Update call to
read_var_value, passing it the block coming from symbol lookup.
* infrun.c (insert_exception_resume_breakpoint): Likewise.
* language.h (struct language_defn): Add a var_block argument to
the LA_READ_VAR_VALUE method.
* objfiles.c (struct static_link_htab_entry): New.
(static_link_htab_entry_hash): New.
(static_link_htab_entry_eq): New.
(objfile_register_static_link): New.
(objfile_lookup_static_link): New.
(free_objfile): Free the STATIC_LINKS hashed map if needed.
* objfiles.h: Include hashtab.h.
(struct objfile): Add a static_links field.
(objfile_register_static_link): New.
(objfile_lookup_static_link): New.
* printcmd.c (print_variable_and_value): Update call to
read_var_value.
* python/py-finishbreakpoint.c (bpfinishpy_init): Likewise.
* python/py-frame.c (frapy_read_var): Update call to
read_var_value, passing it the block coming from symbol lookup.
* python/py-framefilter.c (extract_sym): Add a sym_block
parameter and set the pointed value to NULL (TODO).
(enumerate_args): Update call to extract_sym.
(enumerate_locals): Update calls to extract_sym and to
read_var_value.
* python/py-symbol.c (sympy_value): Update call to
read_var_value (TODO).
* stack.c (read_frame_local): Update call to read_var_value.
(read_frame_arg): Likewise.
(return_command): Likewise.
* symtab.h (struct symbol_block_ops): Add a get_frame_base
method.
(struct symbol): Add a block field.
(SYMBOL_BLOCK): New accessor.
* valops.c (value_of_variable): Remove frame/block handling and
pass the block argument to read_var_value, which does this job
now.
(value_struct_elt_for_reference): Update calls to
read_var_value.
(value_of_this): Pass the block found to read_var_value.
* value.h (read_var_value): Add a var_block argument.
(default_read_var_value): Likewise.
gdb/testsuite/ChangeLog:
* gdb.base/nested-subp1.exp: New file.
* gdb.base/nested-subp1.c: New file.
* gdb.base/nested-subp2.exp: New file.
* gdb.base/nested-subp2.c: New file.
* gdb.base/nested-subp3.exp: New file.
* gdb.base/nested-subp3.c: New file.
This patch is mostly extracted from Pedro's C++ branch. It adds explicit
casts from integer to enum types, where it is really the intention to do
so. This could be because we are ...
* iterating on enum values (we need to iterate on an equivalent integer)
* converting from a value read from bytes (dwarf attribute, agent
expression opcode) to the equivalent enum
* reading the equivalent integer value from another language (Python/Guile)
An exception to that is the casts in regcache.c. It seems to me like
struct regcache's register_status field could be a pointer to an array of
enum register_status. Doing so would waste a bit of memory (4 bytes
used by the enum vs 1 byte used by the current signed char, for each
register). If we switch to C++11 one day, we can define the underlying
type of an enum type, so we could have the best of both worlds.
gdb/ChangeLog:
* arm-tdep.c (set_fp_model_sfunc): Add cast from integer to enum.
(arm_set_abi): Likewise.
* ax-general.c (ax_print): Likewise.
* c-exp.y (exp : string_exp): Likewise.
* compile/compile-loc2c.c (compute_stack_depth_worker): Likewise.
(do_compile_dwarf_expr_to_c): Likewise.
* cp-name-parser.y (demangler_special : DEMANGLER_SPECIAL start):
Likewise.
* dwarf2expr.c (execute_stack_op): Likewise.
* dwarf2loc.c (dwarf2_compile_expr_to_ax): Likewise.
(disassemble_dwarf_expression): Likewise.
* dwarf2read.c (dwarf2_add_member_fn): Likewise.
(read_array_order): Likewise.
(abbrev_table_read_table): Likewise.
(read_attribute_value): Likewise.
(skip_unknown_opcode): Likewise.
(dwarf_decode_macro_bytes): Likewise.
(dwarf_decode_macros): Likewise.
* eval.c (value_f90_subarray): Likewise.
* guile/scm-param.c (gdbscm_make_parameter): Likewise.
* i386-linux-tdep.c (i386_canonicalize_syscall): Likewise.
* infrun.c (handle_command): Likewise.
* memory-map.c (memory_map_start_memory): Likewise.
* osabi.c (set_osabi): Likewise.
* parse.c (operator_length_standard): Likewise.
* ppc-linux-tdep.c (ppc_canonicalize_syscall): Likewise, and use
single return point.
* python/py-frame.c (gdbpy_frame_stop_reason_string): Likewise.
* python/py-symbol.c (gdbpy_lookup_symbol): Likewise.
(gdbpy_lookup_global_symbol): Likewise.
* record-full.c (record_full_restore): Likewise.
* regcache.c (regcache_register_status): Likewise.
(regcache_raw_read): Likewise.
(regcache_cooked_read): Likewise.
* rs6000-tdep.c (powerpc_set_vector_abi): Likewise.
* symtab.c (initialize_ordinary_address_classes): Likewise.
* target-debug.h (target_debug_print_signals): Likewise.
* utils.c (do_restore_current_language): Likewise.
Initially there is some chain (let's say the longest one
but that doe snot matter). Consequently its elements from the middle are
being removed and there remains only some few unambiguous top and bottom ones.
The original idea why the comparison should be sharp ("<") was that if there
are multiple chains like (0xaddr show jmp instruction address):
main(0x100) -> a(0x200) -> d(0x400)
main(0x100) -> a(0x200) -> c(0x300) -> d(0x400)
then - such situation cannot exist - if two jmp instructions in "a" have the
same address they must also jump to the same address (*).
(*) jump to a computed address would be never considered for the DWARF
tail-call records.
So there could be:
main(0x100) -> a(0x200) -> d(0x400)
main(0x100) -> a(0x270) -> c(0x300) -> d(0x400)
But then "a" frame itself is ambiguous and it must not be displayed.
I did not realize that there can be self-tail-call:
main(0x100) -> a(0x200) -> d(0x400)
main(0x100) -> a(0x280) -> a(0x200) -> d(0x400)
which intersects to:
main(0x100) -> <???>? -> a(0x200) -> d(0x400)
And so if the first chain was chosen the
main(0x100) -> a(0x200) -> d(0x400)
then the final intersection has callers+callees==length.
> for example, if CALLERS is 3 and
> CALLEES is 2, what does the chain look like?
main(0x100) -> x(0x150) -> y(0x200) -> <???>? -> a(0x200) -> d(0x400)
And if LENGTH is 7 then:
call_site[0] = main(0x100)
call_site[1] = x(0x150)
call_site[2] = y(0x200)
call_site[3] = garbage
call_site[4] = garbage
call_site[5] = a(0x200)
call_site[6] = d(0x400)
gdb/ChangeLog
2015-06-01 Andreas Schwab <schwab@linux-m68k.org>
Jan Kratochvil <jan.kratochvil@redhat.com>
PR symtab/18392
* dwarf2-frame-tailcall.c (pretended_chain_levels): Correct
assertion.
* dwarf2loc.c (chain_candidate): Likewise.
gdb/testsuite/ChangeLog
2015-06-01 Jan Kratochvil <jan.kratochvil@redhat.com>
PR symtab/18392
* gdb.arch/amd64-tailcall-self.S: New file.
* gdb.arch/amd64-tailcall-self.c: New file.
* gdb.arch/amd64-tailcall-self.exp: New file.
This is the second part of enhancing the debugger to print the value
of arrays of records whose size is variable when only standard DWARF
info is available (no GNAT encoding). For instance:
subtype Small_Type is Integer range 0 .. 10;
type Record_Type (I : Small_Type := 0) is record
S : String (1 .. I);
end record;
type Array_Type is array (Integer range <>) of Record_Type;
A1 : Array_Type := (1 => (I => 0, S => <>),
2 => (I => 1, S => "A"),
3 => (I => 2, S => "AB"));
Currently, GDB prints the following output:
(gdb) p a1
$1 = (
The error happens while the ada-valprint module is trying to print
the value of an element of our array. Because of the fact that
the array's element (type Record_Type) has a variant size, the DWARF
info for our array provide the array's stride:
<1><749>: Abbrev Number: 10 (DW_TAG_array_type)
<74a> DW_AT_name : (indirect string, offset: 0xb6d): pck__T18s
<74e> DW_AT_byte_stride : 16
<74f> DW_AT_type : <0x6ea>
And because our array has a stride, ada-valprint treats it the same
way as packed arrays (see ada-valprint.c::ada_val_print_array):
if (TYPE_FIELD_BITSIZE (type, 0) > 0)
val_print_packed_array_elements (type, valaddr, offset_aligned,
0, stream, recurse,
original_value, options);
The first thing that we should notice in the call above is that
the "valaddr" buffer and the associated offset (OFFSET_ALIGNED)
is passed, but that the corresponding array's address is not.
This can be explained by looking inside val_print_packed_array_elements,
where we see that the function unpacks each element of our array from
the buffer alone (ada_value_primitive_packed_val), and then prints
the resulting artificial value instead:
v0 = ada_value_primitive_packed_val (NULL, valaddr + offset,
(i0 * bitsize) / HOST_CHAR_BIT,
(i0 * bitsize) % HOST_CHAR_BIT,
bitsize, elttype);
[...]
val_print (elttype, value_contents_for_printing (v0),
value_embedded_offset (v0), 0, stream,
recurse + 1, v0, &opts, current_language);
Of particular interest, here, is the fact that we call val_print
with a null address, which is OK, since we're providing a buffer
instead (value_contents_for_printing). Also, providing an address
might not always possible, since packing could place elements at
boundaries that are not byte-aligned.
Things go south when val_print tries to see if there is a pretty-printer
that could be applied. In particular, one of the first things that
the Python pretty-printer does is to create a value using our buffer,
and the given address, which in this case is null (see call to
value_from_contents_and_address in gdbpy_apply_val_pretty_printer).
value_from_contents_and_address, in turn immediately tries to resolve
the type, using the given address, which is null. But, because our
array element is a record containing an array whose bound is the value
of one of its elements (the "s" component), the debugging info for
the array's upper bound is a reference...
<3><71a>: Abbrev Number: 7 (DW_TAG_subrange_type)
<71b> DW_AT_type : <0x724>
<71f> DW_AT_upper_bound : <0x703>
... to component "i" of our record...
<2><703>: Abbrev Number: 5 (DW_TAG_member)
<704> DW_AT_name : i
<706> DW_AT_decl_file : 2
<707> DW_AT_decl_line : 6
<708> DW_AT_type : <0x6d1>
<70c> DW_AT_data_member_location: 0
... where that component is located at offset 0 of the start
of the record. dwarf2_evaluate_property correctly determines
the offset where to load the value of the bound from, but then
tries to read that value from inferior memory using the address
that was given, which is null. See case PROP_ADDR_OFFSET in
dwarf2_evaluate_property:
val = value_at (baton->offset_info.type,
pinfo->addr + baton->offset_info.offset);
This triggers a memory error, which then causes the printing to terminate.
Since there are going to be situations where providing an address
alone is not going to be sufficient (packed arrays where array elements
are not stored at byte boundaries), this patch fixes the issue by
enhancing the type resolution to take both address and data. This
follows the same principle as the val_print module, where both
address and buffer ("valaddr") can be passed as arguments. If the data
has already been fetched from inferior memory (or provided by the
debugging info in some form -- Eg a constant), then use that data
instead of reading it from inferior memory.
Note that this should also be a good step towards being able to handle
dynamic types whose value is stored outside of inferior memory
(Eg: in a register).
With this patch, GDB isn't able to print all of A1, but does perform
a little better:
(gdb) p a1
$1 = ((i => 0, s => , (i => 1, s => , (i => 2, s => )
There is another issue which is independent of this one, and will
therefore be patched separately.
gdb/ChangeLog:
* dwarf2loc.h (struct property_addr_info): Add "valaddr" field.
* dwarf2loc.c (dwarf2_evaluate_property): Add handling of
pinfo->valaddr.
* gdbtypes.h (resolve_dynamic_type): Add "valaddr" parameter.
* gdbtypes.c (resolve_dynamic_struct): Set pinfo.valaddr.
(resolve_dynamic_type_internal): Set pinfo.valaddr.
Add handling of addr_stack->valaddr.
(resolve_dynamic_type): Add "valaddr" parameter.
Set pinfo.valaddr field.
* ada-lang.c (ada_discrete_type_high_bound): Update call to
resolve_dynamic_type.
(ada_discrete_type_low_bound): Likewise.
* findvar.c (default_read_var_value): Likewise.
* value.c (value_from_contents_and_address): Likewise.
This patch splits the TRY_CATCH macro into three, so that we go from
this:
~~~
volatile gdb_exception ex;
TRY_CATCH (ex, RETURN_MASK_ERROR)
{
}
if (ex.reason < 0)
{
}
~~~
to this:
~~~
TRY
{
}
CATCH (ex, RETURN_MASK_ERROR)
{
}
END_CATCH
~~~
Thus, we'll be getting rid of the local volatile exception object, and
declaring the caught exception in the catch block.
This allows reimplementing TRY/CATCH in terms of C++ exceptions when
building in C++ mode, while still allowing to build GDB in C mode
(using setjmp/longjmp), as a transition step.
TBC, after this patch, is it _not_ valid to have code between the TRY
and the CATCH blocks, like:
TRY
{
}
// some code here.
CATCH (ex, RETURN_MASK_ERROR)
{
}
END_CATCH
Just like it isn't valid to do that with C++'s native try/catch.
By switching to creating the exception object inside the CATCH block
scope, we can get rid of all the explicitly allocated volatile
exception objects all over the tree, and map the CATCH block more
directly to C++'s catch blocks.
The majority of the TRY_CATCH -> TRY+CATCH+END_CATCH conversion was
done with a script, rerun from scratch at every rebase, no manual
editing involved. After the mechanical conversion, a few places
needed manual intervention, to fix preexisting cases where we were
using the exception object outside of the TRY_CATCH block, and cases
where we were using "else" after a 'if (ex.reason) < 0)' [a CATCH
after this patch]. The result was folded into this patch so that GDB
still builds at each incremental step.
END_CATCH is necessary for two reasons:
First, because we name the exception object in the CATCH block, which
requires creating a scope, which in turn must be closed somewhere.
Declaring the exception variable in the initializer field of a for
block, like:
#define CATCH(EXCEPTION, mask) \
for (struct gdb_exception EXCEPTION; \
exceptions_state_mc_catch (&EXCEPTION, MASK); \
EXCEPTION = exception_none)
would avoid needing END_CATCH, but alas, in C mode, we build with C90,
which doesn't allow mixed declarations and code.
Second, because when TRY/CATCH are wired to real C++ try/catch, as
long as we need to handle cleanup chains, even if there's no CATCH
block that wants to catch the exception, we need for stop at every
frame in the unwind chain and run cleanups, then rethrow. That will
be done in END_CATCH.
After we require C++, we'll still need TRY/CATCH/END_CATCH until
cleanups are completely phased out -- TRY/CATCH in C++ mode will
save/restore the current cleanup chain, like in C mode, and END_CATCH
catches otherwise uncaugh exceptions, runs cleanups and rethrows, so
that C++ cleanups and exceptions can coexist.
IMO, this still makes the TRY/CATCH code look a bit more like a
newcomer would expect, so IMO worth it even if we weren't considering
C++.
gdb/ChangeLog.
2015-03-07 Pedro Alves <palves@redhat.com>
* common/common-exceptions.c (struct catcher) <exception>: No
longer a pointer to volatile exception. Now an exception value.
<mask>: Delete field.
(exceptions_state_mc_init): Remove all parameters. Adjust.
(exceptions_state_mc): No longer pop the catcher here.
(exceptions_state_mc_catch): New function.
(throw_exception): Adjust.
* common/common-exceptions.h (exceptions_state_mc_init): Remove
all parameters.
(exceptions_state_mc_catch): Declare.
(TRY_CATCH): Rename to ...
(TRY): ... this. Remove EXCEPTION and MASK parameters.
(CATCH, END_CATCH): New.
All callers adjusted.
gdb/gdbserver/ChangeLog:
2015-03-07 Pedro Alves <palves@redhat.com>
Adjust all callers of TRY_CATCH to use TRY/CATCH/END_CATCH
instead.
In C, we can forward declare static structure instances. That doesn't
work in C++ though. C++ treats these as definitions. So then the
compiler complains about symbol redefinition, like:
src/gdb/elfread.c:1569:29: error: redefinition of ‘const sym_fns elf_sym_fns_lazy_psyms’
src/gdb/elfread.c:53:29: error: ‘const sym_fns elf_sym_fns_lazy_psyms’ previously declared here
The intent of static here is naturally to avoid making these objects
visible outside the compilation unit. The equivalent in C++ would be
to instead define the objects in the anonymous namespace. But given
that it's desirable to leave the codebase compiling as both C and C++
for a while, this just makes the objects extern.
(base_breakpoint_ops is already declared in breakpoint.h, so we can
just remove the forward declare from breakpoint.c)
gdb/ChangeLog:
2015-02-11 Tom Tromey <tromey@redhat.com>
Pedro Alves <palves@redhat.com>
* breakpoint.c (base_breakpoint_ops): Delete.
* dwarf2loc.c (dwarf_expr_ctx_funcs): Make extern.
* elfread.c (elf_sym_fns_gdb_index, elf_sym_fns_lazy_psyms): Make extern.
* guile/guile.c (guile_extension_script_ops, guile_extension_ops): Make extern.
* ppcnbsd-tdep.c (ppcnbsd2_sigtramp): Make extern.
* python/py-arch.c (arch_object_type): Make extern.
* python/py-block.c (block_syms_iterator_object_type): Make extern.
* python/py-bpevent.c (breakpoint_event_object_type): Make extern.
* python/py-cmd.c (cmdpy_object_type): Make extern.
* python/py-continueevent.c (continue_event_object_type)
* python/py-event.h (GDBPY_NEW_EVENT_TYPE): Remove 'qual'
parameter. Update all callers.
* python/py-evtregistry.c (eventregistry_object_type): Make extern.
* python/py-exitedevent.c (exited_event_object_type): Make extern.
* python/py-finishbreakpoint.c (finish_breakpoint_object_type): Make extern.
* python/py-function.c (fnpy_object_type): Make extern.
* python/py-inferior.c (inferior_object_type, membuf_object_type): Make extern.
* python/py-infevents.c (call_pre_event_object_type)
(inferior_call_post_event_object_type).
(memory_changed_event_object_type): Make extern.
* python/py-infthread.c (thread_object_type): Make extern.
* python/py-lazy-string.c (lazy_string_object_type): Make extern.
* python/py-linetable.c (linetable_entry_object_type)
(linetable_object_type, ltpy_iterator_object_type): Make extern.
* python/py-newobjfileevent.c (new_objfile_event_object_type)
(clear_objfiles_event_object_type): Make extern.
* python/py-objfile.c (objfile_object_type): Make extern.
* python/py-param.c (parmpy_object_type): Make extern.
* python/py-progspace.c (pspace_object_type): Make extern.
* python/py-signalevent.c (signal_event_object_type): Make extern.
* python/py-symtab.c (symtab_object_type, sal_object_type): Make extern.
* python/py-type.c (type_object_type, field_object_type)
(type_iterator_object_type): Make extern.
* python/python.c (python_extension_script_ops)
(python_extension_ops): Make extern.
* stap-probe.c (stap_probe_ops): Make extern.
Consider the following declarations:
type Array_Type is array (Integer range <>) of Integer;
type Record_Type (N : Integer) is record
A : Array_Type (1 .. N);
end record;
R : Record_Type := Get (10);
It defines what Ada programers call a "discriminated record", where
"N" is a component of that record called a "discriminant", and where
"A" is a component defined as an array type whose upper bound is
equal to the value of the discriminant.
So far, we rely on a number of fairly complex GNAT-specific encodings
to handle this situation. This patch is to enhance GDB to be able to
print this record in the case where the compiler has been modified
to replace those encodings by pure DWARF constructs.
In particular, the debugging information generated for the record above
looks like the following. "R" is a record..
.uleb128 0x10 # (DIE (0x13e) DW_TAG_structure_type)
.long .LASF17 # DW_AT_name: "foo__record_type"
... whose is is of course dynamic (not our concern here)...
.uleb128 0xd # DW_AT_byte_size
.byte 0x97 # DW_OP_push_object_address
.byte 0x94 # DW_OP_deref_size
.byte 0x4
.byte 0x99 # DW_OP_call4
.long 0x19b
.byte 0x23 # DW_OP_plus_uconst
.uleb128 0x7
.byte 0x9 # DW_OP_const1s
.byte 0xfc
.byte 0x1a # DW_OP_and
.byte 0x1 # DW_AT_decl_file (foo.adb)
.byte 0x6 # DW_AT_decl_line
... and then has 2 members, fist "n" (our discriminant);
.uleb128 0x11 # (DIE (0x153) DW_TAG_member)
.ascii "n\0" # DW_AT_name
.byte 0x1 # DW_AT_decl_file (foo.adb)
.byte 0x6 # DW_AT_decl_line
.long 0x194 # DW_AT_type
.byte 0 # DW_AT_data_member_location
... and "A"...
.uleb128 0x11 # (DIE (0x181) DW_TAG_member)
.ascii "a\0" # DW_AT_name
.long 0x15d # DW_AT_type
.byte 0x4 # DW_AT_data_member_location
... which is an array ...
.uleb128 0x12 # (DIE (0x15d) DW_TAG_array_type)
.long .LASF18 # DW_AT_name: "foo__record_type__T4b"
.long 0x194 # DW_AT_type
... whose lower bound is implicitly 1, and the upper bound
a reference to DIE 0x153 = "N":
.uleb128 0x13 # (DIE (0x16a) DW_TAG_subrange_type)
.long 0x174 # DW_AT_type
.long 0x153 # DW_AT_upper_bound
This patch enhanced GDB to understand references to other DIEs
where the DIE's address is at an offset of its enclosing type.
The difficulty was that the address used to resolve the array's
type (R's address + 4 bytes) is different from the address used
as the base to compute N's address (an offset to R's address).
We're solving this issue by using a stack of addresses rather
than a single address when trying to resolve a type. Each address
in the stack corresponds to each containing level. For instance,
if resolving the field of a struct, the stack should contain
the address of the field at the top, and then the address of
the struct. That way, if the field makes a reference to an object
of the struct, we can retrieve the address of that struct, and
properly resolve the dynamic property references that struct.
gdb/ChangeLog:
* gdbtypes.h (struct dynamic_prop): New PROP_ADDR_OFFSET enum
kind.
* gdbtypes.c (resolve_dynamic_type_internal): Replace "addr"
parameter by "addr_stack" parameter.
(resolve_dynamic_range): Replace "addr" parameter by
"stack_addr" parameter. Update function documentation.
Update code accordingly.
(resolve_dynamic_array, resolve_dynamic_union)
(resolve_dynamic_struct, resolve_dynamic_type_internal): Likewise.
(resolve_dynamic_type): Update code, following the changes made
to resolve_dynamic_type_internal's interface.
* dwarf2loc.h (struct property_addr_info): New.
(dwarf2_evaluate_property): Replace "address" parameter
by "addr_stack" parameter. Adjust function documentation.
(struct dwarf2_offset_baton): New.
(struct dwarf2_property_baton): Update documentation of
field "referenced_type" to be more general. New field
"offset_info" in union data field.
* dwarf2loc.c (dwarf2_evaluate_property): Replace "address"
parameter by "addr_stack" parameter. Adjust code accordingly.
Add support for PROP_ADDR_OFFSET properties.
* dwarf2read.c (attr_to_dynamic_prop): Add support for
DW_AT_data_member_location attributes as well. Use case
statements instead of if/else condition.
gdb/testsuite/ChangeLog:
* gdb.ada/disc_arr_bound: New testcase.
Tested on x86_64-linux, no regression.
I see the error message "access outside bounds of object referenced
via synthetic pointer" in the two fails below of mips gdb testing
print d[-2]^M
access outside bounds of object referenced via synthetic pointer^M
(gdb) FAIL: gdb.dwarf2/implptrconst.exp: print d[-2]
(gdb) print/d p[-1]^M
access outside bounds of object referenced via synthetic pointer^M
(gdb) FAIL: gdb.dwarf2/implptrpiece.exp: print/d p[-1]
in the first test, 'd[-2]' is processed by GDB as '* (&d[-2])'. 'd'
is a synthetic pointer, so its value is zero, the address of 'd[-2]'
is -2. In dwarf2loc.c:indirect_pieced_value,
/* This is an offset requested by GDB, such as value subscripts.
However, due to how synthetic pointers are implemented, this is
always presented to us as a pointer type. This means we have to
sign-extend it manually as appropriate. */
byte_offset = value_as_address (value);
if (TYPE_LENGTH (value_type (value)) < sizeof (LONGEST))
byte_offset = gdb_sign_extend (byte_offset,
8 * TYPE_LENGTH (value_type (value)));
byte_offset += piece->v.ptr.offset;
We know that the value is really an offset instead of address, so the
fix is to extract the value as an (signed) offset.
gdb:
2015-01-08 Pedro Alves <palves@redhat.com>
Yao Qi <yao@codesourcery.com>
* dwarf2loc.c (indirect_pieced_value): Don't call
gdb_sign_extend. Call extract_signed_integer instead.
* utils.c (gdb_sign_extend): Remove.
* utils.h (gdb_sign_extend): Remove declaration.
This final patch adds the new "compile" command and subcommands, and
all the machinery needed to make it work.
A shared library supplied by gcc is used for all communications with
gcc. Types and most aspects of symbols are provided directly by gdb
to the compiler using this library.
gdb provides some information about the user's code using plain text.
Macros are emitted this way, and DWARF location expressions (and
bounds for VLA) are compiled to C code.
This hybrid approach was taken because, on the one hand, it is better
to provide global declarations and such on demand; but on the other
hand, for local variables, translating DWARF location expressions to C
was much simpler than exporting a full compiler API to gdb -- the same
result, only easier to implement, understand, and debug.
In the ordinary mode, the user's expression is wrapped in a dummy
function. After compilation, gdb inserts the resulting object code
into the inferior, then calls this function.
Access to local variables is provided by noting which registers are
used by location expressions, and passing a structure of register
values into the function. Writes to registers are supported by
copying out these values after the function returns.
This approach was taken so that we could eventually implement other
more interesting features based on this same infrastructure; for
example, we're planning to investigate inferior-side breakpoint
conditions.
gdb/ChangeLog
2014-12-12 Phil Muldoon <pmuldoon@redhat.com>
Jan Kratochvil <jan.kratochvil@redhat.com>
Tom Tromey <tromey@redhat.com>
* NEWS: Update.
* symtab.h (struct symbol_computed_ops) <generate_c_location>: New
field.
* p-lang.c (pascal_language_defn): Update.
* opencl-lang.c (opencl_language_defn): Update.
* objc-lang.c (objc_language_defn): Update.
* m2-lang.c (m2_language_defn): Update.
* language.h (struct language_defn) <la_get_compile_instance,
la_compute_program>: New fields.
* language.c (unknown_language_defn, auto_language_defn)
(local_language_defn): Update.
* jv-lang.c (java_language_defn): Update.
* go-lang.c (go_language_defn): Update.
* f-lang.c (f_language_defn): Update.
* dwarf2loc.h (dwarf2_compile_property_to_c): Declare.
* dwarf2loc.c (dwarf2_compile_property_to_c)
(locexpr_generate_c_location, loclist_generate_c_location): New
functions.
(dwarf2_locexpr_funcs, dwarf2_loclist_funcs): Update.
* defs.h (enum compile_i_scope_types): New.
(enum command_control_type) <compile_control>: New constant.
(struct command_line) <control_u>: New field.
* d-lang.c (d_language_defn): Update.
* compile/compile.c: New file.
* compile/compile-c-support.c: New file.
* compile/compile-c-symbols.c: New file.
* compile/compile-c-types.c: New file.
* compile/compile.h: New file.
* compile/compile-internal.h: New file.
* compile/compile-loc2c.c: New file.
* compile/compile-object-load.c: New file.
* compile/compile-object-load.h: New file.
* compile/compile-object-run.c: New file.
* compile/compile-object-run.h: New file.
* cli/cli-script.c (multi_line_command_p, print_command_lines)
(execute_control_command, process_next_line)
(recurse_read_control_structure): Handle compile_control.
* c-lang.h (c_get_compile_context, c_compute_program): Declare.
* c-lang.c (c_language_defn, cplus_language_defn)
(asm_language_defn, minimal_language_defn): Update.
* ada-lang.c (ada_language_defn): Update.
* Makefile.in (SUBDIR_GCC_COMPILE_OBS, SUBDIR_GCC_COMPILE_SRCS):
New variables.
(SFILES): Add SUBDIR_GCC_COMPILE_SRCS.
(HFILES_NO_SRCDIR): Add compile.h.
(COMMON_OBS): Add SUBDIR_GCC_COMPILE_OBS.
(INIT_FILES): Add SUBDIR_GCC_COMPILE_SRCS.
(compile.o, compile-c-types.o, compile-c-symbols.o)
(compile-object-load.o, compile-object-run.o, compile-loc2c.o)
(compile-c-support.o): New targets.
gdb/doc/ChangeLog
2014-12-12 Phil Muldoon <pmuldoon@redhat.com>
Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.texinfo (Altering): Update.
(Compiling and Injecting Code): New node.
gdb/testsuite/ChangeLog
2014-12-12 Phil Muldoon <pmuldoon@redhat.com>
Jan Kratochvil <jan.kratochvil@redhat.com>
Tom Tromey <tromey@redhat.com>
* configure.ac: Add gdb.compile/.
* configure: Regenerate.
* gdb.compile/Makefile.in: New file.
* gdb.compile/compile-ops.exp: New file.
* gdb.compile/compile-ops.c: New file.
* gdb.compile/compile-tls.c: New file.
* gdb.compile/compile-tls.exp: New file.
* gdb.compile/compile-constvar.S: New file.
* gdb.compile/compile-constvar.c: New file.
* gdb.compile/compile-mod.c: New file.
* gdb.compile/compile-nodebug.c: New file.
* gdb.compile/compile-setjmp-mod.c: New file.
* gdb.compile/compile-setjmp.c: New file.
* gdb.compile/compile-setjmp.exp: New file.
* gdb.compile/compile-shlib.c: New file.
* gdb.compile/compile.c: New file.
* gdb.compile/compile.exp: New file.
* lib/gdb.exp (skip_compile_feature_tests): New proc.
This exports a utility function, dwarf2_reg_to_regnum_or_error, that
was previously private to dwarf2loc.c.
gdb/ChangeLog
2014-12-12 Jan Kratochvil <jan.kratochvil@redhat.com>
* dwarf2loc.h (dwarf2_reg_to_regnum_or_error): Declare.
* dwarf2loc.c (dwarf2_reg_to_regnum_or_error): Rename from
translate_register. Now public.
(dwarf2_compile_expr_to_ax): Update.
This exports dwarf_expr_frame_base_1 so that other code can use it.
gdb/ChangeLog
2014-12-12 Tom Tromey <tromey@redhat.com>
Jan Kratochvil <jan.kratochvil@redhat.com>
* dwarf2loc.c (dwarf_expr_frame_base_1): Remove declaration.
(dwarf_expr_frame_base): Update caller.
(dwarf_expr_frame_base_1): Rename to ...
(func_get_frame_base_dwarf_block): ... this and make it public.
(dwarf2_compile_expr_to_ax, locexpr_describe_location_piece): Update
callers.
* dwarf2loc.h (func_get_frame_base_dwarf_block): New declaration.
This removes dwarf2_compile_expr_to_ax, replacing it with a utility
function that fetches the CFA data and adding the code to actually
compile to an agent expression directly into
dwarf2_compile_expr_to_ax. This refactoring lets a later patch reuse
the new dwarf2_fetch_cfa_info.
gdb/ChangeLog
2014-12-12 Tom Tromey <tromey@redhat.com>
* dwarf2loc.c (dwarf2_compile_expr_to_ax) <DW_OP_call_frame_cfa>:
Update.
* dwarf2-frame.c (dwarf2_fetch_cfa_info): New function, based on
dwarf2_compile_cfa_to_ax.
(dwarf2_compile_cfa_to_ax): Remove.
* dwarf2-frame.h (dwarf2_fetch_cfa_info): Declare.
(dwarf2_compile_cfa_to_ax): Remove.
Pedro Alves
Artemiy Volkov
Andreas Arnez
Jan Kratochvil
Tom Tromey
Yao Qi
Joel Brobecker
Kevin Buettner
David Taylor
Martin Galvan
Doug Evans
Simon Marchi
Pierre-Marie de Rodat
Tom Tromey
Yao Qi