I noticed that read_unsigned_leb128 is declared in defs.h. There's no
reason this should be here, so this patch moves it to dwarf2read.h.
gdb/ChangeLog
2019-05-08 Tom Tromey <tromey@adacore.com>
* dwarf2loc.c: Include dwarf2read.h.
* defs.h (read_unsigned_leb128): Don't declare.
* dwarf2read.h (read_unsigned_leb128): Declare.
While looking at a different Ada problem, I found that printing a
record containing a VLA did not work properly.
I tracked the problem down to dwarf2_evaluate_property trying, and
failing, to compare two types that differed only in qualifiers.
This patch changes dwarf2_evaluate_property to ignore qualifiers when
comparing types.
Tested on x86-64 Fedora 29.
gdb/ChangeLog
2019-05-08 Tom Tromey <tromey@adacore.com>
* dwarf2loc.c (dwarf2_evaluate_property) <PROP_ADDR_OFFSET>:
Compare main types.
gdb/testsuite/ChangeLog
2019-05-08 Tom Tromey <tromey@adacore.com>
* gdb.ada/vla.exp: New file.
* gdb.ada/vla/vla.adb: New file.
DW_OP_addrx is the new name of DW_OP_GNU_addr_index, and DW_FORM_addrx
is the name of DW_FORM_addr_index in the Dwarf 5 standard. This is a small
step towards supporting Dwarf 5 in gdb.
Note: I could not find any tests specifically for *_GNU_addr_index, and
I did not add any new tests, please advise.
This rewrites gdb's TRY/CATCH to plain C++ try/catch. The patch was
largely written by script, though one change (to a comment in
common-exceptions.h) was reverted by hand.
gdb/ChangeLog
2019-04-08 Tom Tromey <tom@tromey.com>
* xml-support.c: Use C++ exception handling.
* x86-linux-nat.c: Use C++ exception handling.
* windows-nat.c: Use C++ exception handling.
* varobj.c: Use C++ exception handling.
* value.c: Use C++ exception handling.
* valprint.c: Use C++ exception handling.
* valops.c: Use C++ exception handling.
* unittests/parse-connection-spec-selftests.c: Use C++ exception
handling.
* unittests/cli-utils-selftests.c: Use C++ exception handling.
* typeprint.c: Use C++ exception handling.
* tui/tui.c: Use C++ exception handling.
* tracefile-tfile.c: Use C++ exception handling.
* top.c: Use C++ exception handling.
* thread.c: Use C++ exception handling.
* target.c: Use C++ exception handling.
* symmisc.c: Use C++ exception handling.
* symfile-mem.c: Use C++ exception handling.
* stack.c: Use C++ exception handling.
* sparc64-linux-tdep.c: Use C++ exception handling.
* solib.c: Use C++ exception handling.
* solib-svr4.c: Use C++ exception handling.
* solib-spu.c: Use C++ exception handling.
* solib-frv.c: Use C++ exception handling.
* solib-dsbt.c: Use C++ exception handling.
* selftest-arch.c: Use C++ exception handling.
* s390-tdep.c: Use C++ exception handling.
* rust-lang.c: Use C++ exception handling.
* rust-exp.y: Use C++ exception handling.
* rs6000-tdep.c: Use C++ exception handling.
* rs6000-aix-tdep.c: Use C++ exception handling.
* riscv-tdep.c: Use C++ exception handling.
* remote.c: Use C++ exception handling.
* remote-fileio.c: Use C++ exception handling.
* record-full.c: Use C++ exception handling.
* record-btrace.c: Use C++ exception handling.
* python/python.c: Use C++ exception handling.
* python/py-value.c: Use C++ exception handling.
* python/py-utils.c: Use C++ exception handling.
* python/py-unwind.c: Use C++ exception handling.
* python/py-type.c: Use C++ exception handling.
* python/py-symbol.c: Use C++ exception handling.
* python/py-record.c: Use C++ exception handling.
* python/py-record-btrace.c: Use C++ exception handling.
* python/py-progspace.c: Use C++ exception handling.
* python/py-prettyprint.c: Use C++ exception handling.
* python/py-param.c: Use C++ exception handling.
* python/py-objfile.c: Use C++ exception handling.
* python/py-linetable.c: Use C++ exception handling.
* python/py-lazy-string.c: Use C++ exception handling.
* python/py-infthread.c: Use C++ exception handling.
* python/py-inferior.c: Use C++ exception handling.
* python/py-gdb-readline.c: Use C++ exception handling.
* python/py-framefilter.c: Use C++ exception handling.
* python/py-frame.c: Use C++ exception handling.
* python/py-finishbreakpoint.c: Use C++ exception handling.
* python/py-cmd.c: Use C++ exception handling.
* python/py-breakpoint.c: Use C++ exception handling.
* python/py-arch.c: Use C++ exception handling.
* printcmd.c: Use C++ exception handling.
* ppc-linux-tdep.c: Use C++ exception handling.
* parse.c: Use C++ exception handling.
* p-valprint.c: Use C++ exception handling.
* objc-lang.c: Use C++ exception handling.
* mi/mi-main.c: Use C++ exception handling.
* mi/mi-interp.c: Use C++ exception handling.
* mi/mi-cmd-stack.c: Use C++ exception handling.
* mi/mi-cmd-break.c: Use C++ exception handling.
* main.c: Use C++ exception handling.
* linux-thread-db.c: Use C++ exception handling.
* linux-tdep.c: Use C++ exception handling.
* linux-nat.c: Use C++ exception handling.
* linux-fork.c: Use C++ exception handling.
* linespec.c: Use C++ exception handling.
* language.c: Use C++ exception handling.
* jit.c: Use C++ exception handling.
* infrun.c: Use C++ exception handling.
* infcmd.c: Use C++ exception handling.
* infcall.c: Use C++ exception handling.
* inf-loop.c: Use C++ exception handling.
* i386-tdep.c: Use C++ exception handling.
* i386-linux-tdep.c: Use C++ exception handling.
* guile/scm-value.c: Use C++ exception handling.
* guile/scm-type.c: Use C++ exception handling.
* guile/scm-symtab.c: Use C++ exception handling.
* guile/scm-symbol.c: Use C++ exception handling.
* guile/scm-pretty-print.c: Use C++ exception handling.
* guile/scm-ports.c: Use C++ exception handling.
* guile/scm-param.c: Use C++ exception handling.
* guile/scm-math.c: Use C++ exception handling.
* guile/scm-lazy-string.c: Use C++ exception handling.
* guile/scm-frame.c: Use C++ exception handling.
* guile/scm-disasm.c: Use C++ exception handling.
* guile/scm-cmd.c: Use C++ exception handling.
* guile/scm-breakpoint.c: Use C++ exception handling.
* guile/scm-block.c: Use C++ exception handling.
* guile/guile-internal.h: Use C++ exception handling.
* gnu-v3-abi.c: Use C++ exception handling.
* gdbtypes.c: Use C++ exception handling.
* frame.c: Use C++ exception handling.
* frame-unwind.c: Use C++ exception handling.
* fbsd-tdep.c: Use C++ exception handling.
* f-valprint.c: Use C++ exception handling.
* exec.c: Use C++ exception handling.
* event-top.c: Use C++ exception handling.
* event-loop.c: Use C++ exception handling.
* eval.c: Use C++ exception handling.
* dwarf2read.c: Use C++ exception handling.
* dwarf2loc.c: Use C++ exception handling.
* dwarf2-frame.c: Use C++ exception handling.
* dwarf2-frame-tailcall.c: Use C++ exception handling.
* dwarf-index-write.c: Use C++ exception handling.
* dwarf-index-cache.c: Use C++ exception handling.
* dtrace-probe.c: Use C++ exception handling.
* disasm-selftests.c: Use C++ exception handling.
* darwin-nat.c: Use C++ exception handling.
* cp-valprint.c: Use C++ exception handling.
* cp-support.c: Use C++ exception handling.
* cp-abi.c: Use C++ exception handling.
* corelow.c: Use C++ exception handling.
* completer.c: Use C++ exception handling.
* compile/compile-object-run.c: Use C++ exception handling.
* compile/compile-object-load.c: Use C++ exception handling.
* compile/compile-cplus-symbols.c: Use C++ exception handling.
* compile/compile-c-symbols.c: Use C++ exception handling.
* common/selftest.c: Use C++ exception handling.
* common/new-op.c: Use C++ exception handling.
* cli/cli-script.c: Use C++ exception handling.
* cli/cli-interp.c: Use C++ exception handling.
* cli/cli-cmds.c: Use C++ exception handling.
* c-varobj.c: Use C++ exception handling.
* btrace.c: Use C++ exception handling.
* breakpoint.c: Use C++ exception handling.
* break-catch-throw.c: Use C++ exception handling.
* arch-utils.c: Use C++ exception handling.
* amd64-tdep.c: Use C++ exception handling.
* ada-valprint.c: Use C++ exception handling.
* ada-typeprint.c: Use C++ exception handling.
* ada-lang.c: Use C++ exception handling.
* aarch64-tdep.c: Use C++ exception handling.
gdb/gdbserver/ChangeLog
2019-04-08 Tom Tromey <tom@tromey.com>
* server.c: Use C++ exception handling.
* linux-low.c: Use C++ exception handling.
* gdbreplay.c: Use C++ exception handling.
This applies ATTRIBUTE_UNUSED_RESULT to ref_ptr::release and updates a
few spots to comply. I believe one use in install_default_visualizer
was in error, fixed by this patch.
gdb/ChangeLog
2019-03-05 Tom Tromey <tromey@adacore.com>
* varobj.c (update_dynamic_varobj_children): Update.
(install_default_visualizer): Use reset, not release.
* value.c (set_internalvar): Update.
* dwarf2loc.c (value_of_dwarf_reg_entry): Update.
* common/gdb_ref_ptr.h (class ref_ptr) <release>: Add
ATTRIBUTE_UNUSED_RESULT.
This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
This patch deletes ada-lang.c's move_bits function entirely, and
replaces all calls to it by calls to copy_bitwise instead. Because
the latter function was declared locally inside dwarf2loc.c, this
patch also move the function to a common area, and makes it non-static.
gdb/ChangeLog:
* ada-lang.c (move_bits): Delete. Update all callers to use
copy_bitwise instead.
* dwarf2loc.c (copy_bitwise, bits_to_str::bits_to_str)
(selftests::check_copy_bitwise, selftests::copy_bitwise_tests):
Move from here to utils.c.
(_initialize_dwarf2loc): Remove call to register copy_bitwise
selftests.
* utils.h (copy_bitwise): Add declaration.
* utils.c (copy_bitwise, bits_to_str::bits_to_str)
(selftests::check_copy_bitwise, selftests::copy_bitwise_tests):
Moved here from dwarf2loc.c.
(_initialize_utils): Register copy_bitwise selftests.
Tested on x86_64-linux, no regression. Also tested using AdaCore's
testsuite on a collection of small endian and big endian platforms.
This fixes all the straightforward -Wshadow=local warnings in gdb. A
few standard approaches are used here:
* Renaming an inner (or outer, but more commonly inner) variable;
* Lowering a declaration to avoid a clash;
* Moving a declaration into a more inner scope to avoid a clash,
including the special case of moving a declaration into a loop header.
I did not consider any of the changes in this patch to be particularly
noteworthy, though of course they should all still be examined.
gdb/ChangeLog
2018-10-04 Tom Tromey <tom@tromey.com>
* ctf.c (SET_ARRAY_FIELD): Rename "u32".
* p-valprint.c (pascal_val_print): Split inner "i" variable.
* xtensa-tdep.c (xtensa_push_dummy_call): Declare "i" in loop
header.
* xstormy16-tdep.c (xstormy16_push_dummy_call): Declare "val" in
more inner scope.
* xcoffread.c (read_xcoff_symtab): Rename inner "symbol".
* varobj.c (varobj_update): Rename inner "newobj",
"type_changed".
* valprint.c (generic_emit_char): Rename inner "buf".
* valops.c (find_overload_match): Rename inner "temp".
(value_struct_elt_for_reference): Declare "v" in more inner
scope.
* v850-tdep.c (v850_push_dummy_call): Rename "len".
* unittests/array-view-selftests.c (run_tests): Rename inner
"vec".
* tui/tui-stack.c (tui_show_frame_info): Declare "i" in loop
header.
* tracepoint.c (merge_uploaded_trace_state_variables): Declare
"tsv" in more inner scope.
(print_one_static_tracepoint_marker): Rename inner
"tuple_emitter".
* tic6x-tdep.c (tic6x_analyze_prologue): Declare "inst" lower.
(tic6x_push_dummy_call): Don't redeclare "addr".
* target-float.c: Declare "dto" lower.
* symtab.c (lookup_local_symbol): Rename inner "sym".
(find_pc_sect_line): Rename inner "pc".
* stack.c (print_frame): Don't redeclare "gdbarch".
(return_command): Rename inner "gdbarch".
* s390-tdep.c (s390_prologue_frame_unwind_cache): Renam inner
"sp".
* rust-lang.c (rust_internal_print_type): Declare "i" in loop
header.
* rs6000-tdep.c (ppc_process_record): Rename inner "addr".
* riscv-tdep.c (riscv_push_dummy_call): Declare "info" in inner
scope.
* remote.c (remote_target::update_thread_list): Don't redeclare
"tp".
(remote_target::process_initial_stop_replies): Rename inner
"thread".
(remote_target::remote_parse_stop_reply): Don't redeclare "p".
(remote_target::wait_as): Don't redeclare "stop_reply".
(remote_target::get_thread_local_address): Rename inner
"result".
(remote_target::get_tib_address): Likewise.
Consider a vla variable 'a' in function f1:
...
<2><1a7>: Abbrev Number: 11 (DW_TAG_variable)
<1a8> DW_AT_description : a
<1aa> DW_AT_abstract_origin: <0x311>
...
with abstract origin 'a':
...
<2><311>: Abbrev Number: 3 (DW_TAG_variable)
<312> DW_AT_name : a
<317> DW_AT_type : <0x325>
...
and inherited abstract vla type:
...
<1><325>: Abbrev Number: 9 (DW_TAG_array_type)
<326> DW_AT_type : <0x33a>
<2><32e>: Abbrev Number: 10 (DW_TAG_subrange_type)
<32f> DW_AT_type : <0x2ea>
<333> DW_AT_upper_bound : 5 byte block: fd 1b 3 0 0
(DW_OP_GNU_variable_value: <0x31b>)
...
where the upper bound refers to this artificial variable D.1922 without location
attribute:
...
<2><31b>: Abbrev Number: 8 (DW_TAG_variable)
<31c> DW_AT_description : (indirect string, offset: 0x39a): D.1922
<320> DW_AT_type : <0x2ea>
<324> DW_AT_artificial : 1
...
Currently, when we execute "p sizeof (a)" in f1, the upper bound is calculated
by evaluating the DW_OP_GNU_variable_value expression referring to D.1922, but
since that die doesn't have a location attribute, we get:
...
value has been optimized out
...
However, there's also artificial variable D.4283 that is sibling of vla
variable 'a', has artificial variable D.1922 as abstract origin, and has a
location attribute:
...
<2><1ae>: Abbrev Number: 12 (DW_TAG_variable)
<1af> DW_AT_description : (indirect string, offset: 0x1f8): D.4283
<1b3> DW_AT_abstract_origin: <0x31b>
<1b7> DW_AT_location : 11 byte block: 75 1 8 20 24 8 20 26 31 1c 9f
(DW_OP_breg5 (rdi):1; DW_OP_const1u: 32;
DW_OP_shl; DW_OP_const1u: 32; DW_OP_shra;
DW_OP_lit1; DW_OP_minus; DW_OP_stack_value)
...
The intended behaviour for DW_OP_GNU_variable_value is to find a die that
refers to D.1922 as abstract origin, has a location attribute and is
'in scope', so the expected behaviour is:
...
$1 = 6
...
The 'in scope' concept can be thought of as variable D.1922 having name
attribute "D.1922", and variable D.4283 inheriting that attribute, resulting
in D.4283 being declared with name "D.1922" alongside vla a in f1, and when we
lookup "DW_OP_GNU_variable_value D.1922", it should work as if we try to find
the value of a variable named "D.1922" on the gdb command line using
"p D.1922", and we should return the value of D.4283.
This patch fixes the case described above, by:
- adding a field abstract_to_concrete to struct dwarf2_per_objfile,
- using that field to keep track of which concrete dies are instances of an
abstract die, and
- using that information when getting the value DW_OP_GNU_variable_value.
Build and reg-tested on x86_64-linux.
2018-09-05 Tom de Vries <tdevries@suse.de>
* dwarf2loc.c (sect_variable_value): Call indirect_synthetic_pointer
with resolve_abstract_p == true.
(indirect_synthetic_pointer): Add resolve_abstract_p parameter,
defaulting to false. Propagate resolve_abstract_p to
dwarf2_fetch_die_loc_sect_off.
* dwarf2loc.h (dwarf2_fetch_die_loc_sect_off): Add resolve_abstract_p
parameter, defaulting to false.
* dwarf2read.c (read_variable): Add variable to abstract_to_concrete.
(dwarf2_fetch_die_loc_sect_off): Add and handle resolve_abstract_p
parameter.
* dwarf2read.h (struct die_info): Forward-declare.
(die_info_ptr): New typedef.
(struct dwarf2_per_objfile): Add abstract_to_concrete field.
* gdb.dwarf2/varval.exp: Add test.
This change/patch substitues BLOCK_ENTRY_PC for BLOCK_START in
places where BLOCK_START is used to obtain the address at which
execution should enter the block. Since blocks can now contain
non-contiguous ranges, the BLOCK_START - which is still be the
very lowest address in the block - might not be the same as
BLOCK_ENTRY_PC.
There is a change to infrun.c which is less obvious and less mechanical.
I'm posting it as a separate patch.
gdb/ChangeLog:
* ax-gdb.c (gen_var_ref): Use BLOCK_ENTRY_PC in place of
BLOCK_START.
* blockframe.c (get_pc_function_start): Likewise.
* compile/compile-c-symbols.c (convert_one_symbol): Likewise.
(gcc_symbol_address): Likewise.
* compile/compile-object-run.c (compile_object_run): Likewise.
* compile/compile.c (get_expr_block_and_pc): Likewise.
* dwarf2loc.c (dwarf2_find_location_expression): Likewise.
(func_addr_to_tail_call_list): Likewise.
* findvar.c (default_read_var_value): Likewise.
* inline-frame.c (inline_frame_this_id): Likewise.
(skip-inline_frames): Likewise.
* infcmd.c (until_next_command): Likewise.
* linespec.c (convert_linespec_to_sals): Likewise.
* parse.c (parse_exp_in_context_1): Likewise.
* printcmd.c (build_address_symbolic): likewise.
(info_address_command): Likewise.
symtab.c (find_function_start_sal): Likewise.
(skip_prologue_sal): Likewise.
(find_function_alias_target): Likewise.
(find_gnu_ifunc): Likewise.
* stack.c (find_frame_funname): Likewise.
* symtab.c (fixup_symbol_section): Likewise.
(find_function_start_sal): Likewise.
(skip_prologue_sal): Likewsie.
(find_function_alias_target): Likewise.
(find_gnu_ifunc): Likewise.
* tracepoint.c (info_scope_command): Likewise.
* value.c (value_fn_field): Likewise.
This patch adds support for DW_OP_GNU_variable_value to GDB.
Jakub Jelinek provides a fairly expansive discussion of this DWARF
expression opcode in his GCC patch...
https://gcc.gnu.org/ml/gcc-patches/2017-02/msg01499.html
It has also been proposed for addition to the DWARF Standard:
http://www.dwarfstd.org/ShowIssue.php?issue=161109.2
If compiled with a suitable version of GCC, the test case associated
with GCC Bug 77589 uses DW_OP_GNU_variable_value in a DW_AT_byte_stride
expression. Here's a link to the bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77589
This is what the DWARF looks like. Look at the last line, which has
the DW_AT_byte_stride expression:
<2><e1>: Abbrev Number: 12 (DW_TAG_variable)
<e2> DW_AT_name : (indirect string, offset: 0x115): span.0
<e6> DW_AT_type : <0x2e>
<ea> DW_AT_artificial : 1
<ea> DW_AT_location : 3 byte block: 91 b0 7f (DW_OP_fbreg: -80)
...
<2><178>: Abbrev Number: 18 (DW_TAG_subrange_type)
<179> DW_AT_lower_bound : 4 byte block: 97 23 20 6 (DW_OP_push_object_address; DW_OP_plus_uconst: 32; DW_OP_deref)
<17e> DW_AT_upper_bound : 4 byte block: 97 23 28 6 (DW_OP_push_object_address; DW_OP_plus_uconst: 40; DW_OP_deref)
<183> DW_AT_byte_stride : 10 byte block: 97 23 18 6 fd e1 0 0 0 1e (DW_OP_push_object_address; DW_OP_plus_uconst: 24; DW_OP_deref; DW_OP_GNU_variable_value: <0xe1>; DW_OP_mul)
A patch to readelf, which I'm also submitting, is required to do this
decoding.
I found that GDB gave me the correct answer for "p c40pt(2)" once I
(correctly) implemented DW_OP_GNU_variable_value.
I also have test case (later in this series) which uses the DWARF
assembler and, therefore, do not rely on having a compiler with this
support.
gdb/ChangeLog:
* dwarf2expr.h (struct dwarf_expr_context): Add virtual method
dwarf_variable_value.
* dwarf2-frame.c (class dwarf_expr_executor):
Add override for dwarf_variable_value.
* dwarf2loc.c (class dwarf_evaluate_loc_desc): Likewise.
(class symbol_needs_eval_context): Likewise.
(indirect_synthetic_pointer): Add forward declaration.
(sect_variable_value): New function.
(dwarf2_compile_expr_to_ax): Add case for DW_OP_GNU_variable_value.
* dwarf2expr.c (dwarf_expr_context::execute_stack_op): Add case
for DW_OP_GNU_variable_value.
When compiling vla-optimized-out.c with -O3 and a recent gcc, and trying to
print the vla a in f1, we run into this gdb exception:
...
Cannot find matching parameter at DW_TAG_call_site 0x4003be at main
...
This is a regression introduced by 42dc7699a2 "[gdb/exp] Fix printing of type
of optimized out vla".
This patch fixes the regression by wrapping the ctx.eval call in
dwarf2_locexpr_baton_eval in try/catch, similar to what is done in
dwarf2_evaluate_loc_desc_full.
Build and reg-tested on x86_64-linux.
2018-07-25 Tom de Vries <tdevries@suse.de>
* dwarf2loc.c (dwarf2_locexpr_baton_eval): Wrap ctx.eval call in
try/catch.
* gdb.base/vla-optimized-out-o3.exp: New file. Reuse
vla-optimized-out.c.
This patch adds a missing ATTRIBUTE_NORETURN. This lets
-Wimplicit-fallthrough recognize that a given case does not fall
through.
ChangeLog
2018-05-04 Tom Tromey <tom@tromey.com>
* dwarf2loc.c (unimplemented): Add ATTRIBUTE_NORETURN.
value_incref returned its argument just as a convenience, which in the
end turned out to only be used in precisely the cases where
new_reference helps. So, this patch changes value_incref to return
void and changes some value-using code to use new_reference.
I also noticed that the comments for value_incref and value_decref
were swapped, so this patch fixes those.
ChangeLog
2018-04-30 Tom Tromey <tom@tromey.com>
* varobj.c (install_new_value): Use new_reference.
* value.h (value_incref): Return void. Swap intro comment with
value_decref.
* value.c (set_value_parent): Use new_reference.
(value_incref): Return void. Update intro comment.
(release_value): Use new_reference.
* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Use new_reference.
I noticed the existence of -Wsuggest-override and so this patch
enables it for gdb. It found a few spots that could use "override".
Also I went ahead and removed all uses of the "OVERRIDE" macro.
Using override is beneficial because it makes it harder to change a
base class and then forget to change a derived class.
Tested by the buildbot.
ChangeLog
2018-04-27 Tom Tromey <tom@tromey.com>
* configure: Rebuild.
* warning.m4 (AM_GDB_WARNINGS): Add -Wsuggest-override.
* dwarf2loc.c (class dwarf_evaluate_loc_desc): Use "override", not
"OVERRIDE".
(class symbol_needs_eval_context): Likewise.
* dwarf2read.c (mock_mapped_index::symbol_name_count)
(mock_mapped_index::symbol_name_at): Use "override". Remove
"virtual".
* dwarf2-frame.c (dwarf_expr_executor::get_addr_index): Use
"override".
(class dwarf_expr_executor): Use "override", not "OVERRIDE".
* aarch64-tdep.c (instruction_reader::read): Use "override".
(instruction_reader_test::read): Likewise.
* arm-tdep.c (instruction_reader::read): Use "override".
(instruction_reader_thumb::read): Likewise.
gdbserver/ChangeLog
2018-04-27 Tom Tromey <tom@tromey.com>
* configure: Rebuild.
struct value is internally reference counted and so, while it also has
some ownership rules unique to it, it makes sense to use a gdb_ref_ptr
when managing it automatically.
This patch removes the existing unique_ptr specialization in favor of
a reference-counted pointer. It also introduces two other
clarifications:
1. Rename value_free to value_decref, which I think is more in line
with what the function actually does; and
2. Change release_value to return a gdb_ref_ptr. This change allows
us to remove the confusing release_value_or_incref function,
primarily by making it much simpler to reason about the result of
release_value.
gdb/ChangeLog
2018-04-06 Tom Tromey <tom@tromey.com>
* varobj.c (varobj_clear_saved_item)
(update_dynamic_varobj_children, install_new_value, ~varobj):
Update.
* value.h (value_incref): Move declaration earlier.
(value_decref): Rename from value_free.
(struct value_ref_policy): New.
(value_ref_ptr): New typedef.
(struct value_deleter): Remove.
(gdb_value_up): Remove typedef.
(release_value): Change return type.
(release_value_or_incref): Remove.
* value.c (set_value_parent): Update.
(value_incref): Change return type.
(value_decref): Rename from value_free.
(value_free_to_mark, free_all_values, free_value_chain): Update.
(release_value): Return value_ref_ptr.
(release_value_or_incref): Remove.
(record_latest_value, set_internalvar, clear_internalvar):
Update.
* stack.c (info_frame_command): Don't call value_free.
* python/py-value.c (valpy_dealloc, valpy_new)
(value_to_value_object): Update.
* printcmd.c (do_examine): Update.
* opencl-lang.c (lval_func_free_closure): Update.
* mi/mi-main.c (register_changed_p): Don't call value_free.
* mep-tdep.c (mep_frame_prev_register): Don't call value_free.
* m88k-tdep.c (m88k_frame_prev_register): Don't call value_free.
* m68hc11-tdep.c (m68hc11_frame_prev_register): Don't call
value_free.
* guile/scm-value.c (vlscm_free_value_smob)
(vlscm_scm_from_value): Update.
* frame.c (frame_register_unwind, frame_unwind_register_signed)
(frame_unwind_register_unsigned, get_frame_register_bytes)
(put_frame_register_bytes): Don't call value_free.
* findvar.c (address_from_register): Don't call value_free.
* dwarf2read.c (dwarf2_compute_name): Don't call value_free.
* dwarf2loc.c (entry_data_value_free_closure)
(value_of_dwarf_reg_entry, free_pieced_value_closure)
(dwarf2_evaluate_loc_desc_full): Update.
* breakpoint.c (update_watchpoint, breakpoint_init_inferior)
(~bpstats, bpstats, bpstat_clear_actions, watchpoint_check)
(~watchpoint, watch_command_1)
(invalidate_bp_value_on_memory_change): Update.
* alpha-tdep.c (alpha_register_to_value): Don't call value_free.
This removes make_cleanup_value_free, in favor of a unique_ptr
specialization.
Regression tested by the buildbot.
gdb/ChangeLog
2017-10-08 Tom Tromey <tom@tromey.com>
* utils.h (make_cleanup_value_free): Remove.
* utils.c (do_value_free, struct cleanup): Remove.
* dwarf2loc.c (dwarf2_evaluate_loc_desc_full) <DWARF_VALUE_STACK>:
Use gdb_value_up.
* value.h (struct value_deleter): New.
(gdb_value_up): New typedef.
With the growing number of selftests, I think it would be useful to be
able to run only a subset of the tests. This patch associates a name to
each registered selftest. It then allows doing something like:
(gdb) maintenance selftest aarch64
Running self-tests.
Running selftest aarch64-analyze-prologue.
Running selftest aarch64-process-record.
Ran 2 unit tests, 0 failed
or with gdbserver:
./gdbserver --selftest=aarch64
In both cases, only the tests that contain "aarch64" in their name are
ran. To help validate that the tests you want to run were actually ran,
it also prints a message with the test name before running each test.
Right now, all the arch-dependent tests are registered as a single test
of the selftests. To be able to filter those too, I made them
"first-class citizen" selftests. The selftest type is an interface,
with different implementations for "simple selftests" and "arch
selftests". The run_tests function simply iterates on that an invokes
operator() on each test.
I changed the tests data structure from a vector to a map, because
- it allows iterating in a stable (alphabetical) order
- it allows to easily verify if a test with a given name has been
registered, to avoid duplicates
There's also a new command "maintenance info selftests" that lists the
registered selftests.
gdb/ChangeLog:
* common/selftest.h (selftest): New struct/interface.
(register_test): Add name parameter, add new overload.
(run_tests): Add filter parameter.
(for_each_selftest_ftype): New typedef.
(for_each_selftest): New declaration.
* common/selftest.c (tests): Change type to
map<string, unique_ptr<selftest>>.
(simple_selftest): New struct.
(register_test): New function.
(register_test): Add name parameter and use it.
(run_tests): Add filter parameter and use it. Add prints.
Adjust to vector -> map change.
* aarch64-tdep.c (_initialize_aarch64_tdep): Add names when
registering selftests.
* arm-tdep.c (_initialize_arm_tdep): Likewise.
* disasm-selftests.c (_initialize_disasm_selftests): Likewise.
* dwarf2-frame.c (_initialize_dwarf2_frame): Likewise.
* dwarf2loc.c (_initialize_dwarf2loc): Likewise.
* findvar.c (_initialize_findvar): Likewise.
* gdbarch-selftests.c (_initialize_gdbarch_selftests): Likewise.
* maint.c (maintenance_selftest): Update call to run_tests.
(maintenance_info_selftests): New function.
(_initialize_maint_cmds): Register "maintenance info selftests"
command. Update "maintenance selftest" doc.
* regcache.c (_initialize_regcache): Add names when registering
selftests.
* rust-exp.y (_initialize_rust_exp): Likewise.
* selftest-arch.c (gdbarch_selftest): New struct.
(gdbarch_tests): Remove.
(register_test_foreach_arch): Add name parameter. Call
register_test.
(tests_with_arch): Remove, move most content to
gdbarch_selftest::operator().
(_initialize_selftests_foreach_arch): Remove.
* selftest-arch.h (register_test_foreach_arch): Add name
parameter.
(run_tests_with_arch): New declaration.
* utils-selftests.c (_initialize_utils_selftests): Add names
when registering selftests.
* utils.c (_initialize_utils): Likewise.
* unittests/array-view-selftests.c
(_initialize_array_view_selftests): Likewise.
* unittests/environ-selftests.c (_initialize_environ_selftests):
Likewise.
* unittests/function-view-selftests.c
(_initialize_function_view_selftests): Likewise.
* unittests/offset-type-selftests.c
(_initialize_offset_type_selftests): Likewise.
* unittests/optional-selftests.c
(_initialize_optional_selftests): Likewise.
* unittests/scoped_restore-selftests.c
(_initialize_scoped_restore_selftests): Likewise.
* NEWS: Document "maintenance selftest" and "maint info
selftests".
gdb/gdbserver/ChangeLog:
* server.c (captured_main): Accept argument for --selftest.
Update run_tests call.
* linux-x86-tdesc-selftest.c (initialize_low_tdesc): Add names
when registering selftests.
gdb/doc/ChangeLog:
* gdb.texinfo (Maintenance Commands): Document filter parameter
of "maint selftest". Document "maint info selftests" command.
Replace int with bool, because that's what it is.
gdb/ChangeLog:
* dwarf2expr.h (dwarf_expr_piece) <v.mem.in_stack_memory>:
Change type to bool.
(dwarf_stack_value) <in_stack_memory>: Likewise.
(dwarf_expr_context) <push_address>: Change parameter type to
bool.
<fetch_in_stack_memory>: Change return type to bool.
<push>: Change parameter type to bool.
* dwarf2expr.c (dwarf_expr_context::push): Change parameter type
to bool.
(dwarf_expr_context::push_address): Likewise.
(dwarf_expr_context::fetch_in_stack_memory): Change return type
to bool.
(dwarf_expr_context::execute_stack_op): Adjust.
* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Adjust.
Change the manually managed array dwarf_expr_piece::piece with an
std::vector. After passing the pieces array to allocate_piece_closure,
dwarf2_evaluate_loc_desc_full doesn't need that data anymore. We can
therefore move the content of the vector to avoid copying it.
Reg-tested on the buildbot.
gdb/ChangeLog:
* dwarf2expr.h (struct dwarf_expr_piece): Move up.
(struct dwarf_expr_context) <n_pieces>: Remove.
<pieces>: Change type to std::vector.
* dwarf2expr.c (dwarf_expr_context::dwarf_expr_context): Adjust.
(dwarf_expr_context::~dwarf_expr_context): Don't manually free
pieces.
(dwarf_expr_context::add_piece): Adjust.
* dwarf2loc.c (struct piece_closure): Initialize fields.
<n_pieces>: Remove.
<pieces>: Change type to std::vector.
(allocate_piece_closure): Adjust, change parameter to
std::vector rvalue and std::move it to piece_closure.
(rw_pieced_value): Adjust.
(check_pieced_synthetic_pointer): Adjust.
(indirect_synthetic_pointer): Adjust.
(coerce_pieced_ref): Adjust.
(free_pieced_value_closure): Adjust. Use delete to free
piece_closure.
(dwarf2_evaluate_loc_desc_full): Adjust. std::move ctx.pieces
to allocate_piece_closure.
(dwarf2_loc_desc_get_symbol_read_needs): Adjust.
In multiple places, we pass the gdbarch as an argument to some
functions, even though it's available in the agent_expr structure also
passed to the same functions. Remove these arguments and replace their
usage with accesses to agent_expr::gdbarch.
gdb/ChangeLog:
* dwarf2loc.h (dwarf2_compile_expr_to_ax): Remove gdbarch
parameter.
* symtab.h (struct symbol_computed_ops::tracepoint_var_ref):
Likewise.
* dwarf2loc.c (dwarf2_compile_expr_to_ax): Remove gdbarch
parameter, use agent_expr::gdbarch instead, update function
calls.
(locexpr_tracepoint_var_ref): Likewise.
(loclist_tracepoint_var_ref): Likewise.
* ax-gdb.c (gen_trace_static_fields): Likewise.
(gen_traced_pop): Likewise.
(gen_frame_args_address): Likewise.
(gen_frame_locals_address): Likewise.
(gen_var_ref): Likewise.
(gen_struct_ref_recursive): Likewise.
(gen_static_field): Likewise.
(gen_maybe_namespace_elt): Likewise.
(gen_expr): Likewise.
(gen_trace_for_var): Likewise.
(gen_trace_for_expr): Likewise.
(gen_trace_for_return_address): Likewise.
This Rust bug report:
https://github.com/rust-lang/rust/issues/41970
noted an error from gdb. What is happening here (for me, the original
report had a different error) is that a pieced DWARF expression is not
writing to every byte in the resulting value. GDB errors in this
case. However, it seems to me that it is always valid to write fewer
bytes; the issue comes from writing too many -- that is, the test is
reversed. The test was also checking the sub-object, but this also
seems incorrect, as it's expected for the expression to write the
entirety of the enclosing object. So, this patch reverses the test
and applies it to the outer type, not the subobject type.
Regtested on the buildbot.
gdb/ChangeLog
2017-07-09 Tom Tromey <tom@tromey.com>
* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Reverse size
check and apply to outer type.
gdb/testsuite/ChangeLog
2017-07-09 Tom Tromey <tom@tromey.com>
* gdb.dwarf2/shortpiece.exp: New file.
This commit eliminates make_cleanup_obstack_free, replacing it with a
new auto_obstack type that inherits obstack to add cdtors.
These changes in the parsers may not be obvious:
- obstack_init (&name_obstack);
- make_cleanup_obstack_free (&name_obstack);
+ name_obstack.clear ();
Here, the 'name_obstack' variable is a global. The change means that
the obstack's contents from a previous parse will stay around until
the next parsing starts. I.e., memory won't be reclaimed until then.
I don't think that's a problem, these objects don't really grow much
at all.
The other option I tried was to add a separate type that is like
auto_obstack but manages an external obstack, just for those cases. I
like the current approach better as that other approach adds more
boilerplate and yet another type to learn.
gdb/ChangeLog:
2017-06-27 Pedro Alves <palves@redhat.com>
* c-exp.y (name_obstack): Now an auto_obstack.
(yylex): Use auto_obstack::clear.
(c_parse): Use auto_obstack::clear instead of reinitializing and
freeing the obstack.
* c-lang.c (evaluate_subexp_c): Use auto_obstack.
* d-exp.y (name_obstack): Now an auto_obstack.
(yylex): Use auto_obstack::clear.
(d_parse): Use auto_obstack::clear instead of reinitializing and
freeing the obstack.
* dwarf2loc.c (fetch_const_value_from_synthetic_pointer): Use
auto_obstack.
* dwarf2read.c (create_addrmap_from_index)
(dwarf2_build_psymtabs_hard)
(update_enumeration_type_from_children): Likewise.
* gdb_obstack.h (auto_obstack): New type.
* go-exp.y (name_obstack): Now an auto_obstack.
(build_packaged_name): Use auto_obstack::clear.
(go_parse): Use auto_obstack::clear instead of reinitializing and
freeing the obstack.
* linux-tdep.c (linux_make_mappings_corefile_notes): Use
auto_obstack.
* printcmd.c (printf_wide_c_string, ui_printf): Use auto_obstack.
* rust-exp.y (work_obstack): Now an auto_obstack.
(rust_parse, rust_lex_tests): Use auto_obstack::clear instead of
reinitializing and freeing the obstack.
* utils.c (do_obstack_free, make_cleanup_obstack_free): Delete.
(host_char_to_target): Use auto_obstack.
* utils.h (make_cleanup_obstack_free): Delete declaration.
* valprint.c (generic_emit_char, generic_printstr): Use
auto_obstack.
In some cases we've been replacing heap-allocated gdb_byte buffers
managed with xmalloc/make_cleanup(xfree) with gdb::vector<gdb_byte>.
That usually pessimizes the code a little bit because std::vector
value-initializes elements (which for gdb_byte means
zero-initialization), while if you're creating a temporary buffer,
you're most certaintly going to fill it in with some data. An
alternative is to use
unique_ptr<gdb_byte[]> buf (new gdb_byte[size]);
but it looks like that's not very popular.
Recently, a use of obstacks in dwarf2read.c was replaced with
std::vector<gdb_byte> and that as well introduced a pessimization for
always memsetting the buffer when it's garanteed that the zeros will
be overwritten immediately. (see dwarf2read.c change in this patch to
find it.)
So here's a different take at addressing this issue "by design":
#1 - Introduce default_init_allocator<T>
I.e., a custom allocator that does default construction using default
initialization, meaning, no more zero initialization. That's the
default_init_allocation<T> class added in this patch.
See "Notes" at
<http://en.cppreference.com/w/cpp/container/vector/resize>.
#2 - Introduce def_vector<T>
I.e., a convenience typedef, because typing the allocator is annoying:
using def_vector<T> = std::vector<T, gdb::default_init_allocator<T>>;
#3 - Introduce byte_vector
Because gdb_byte vectors will be the common thing, add a convenience
"byte_vector" typedef:
using byte_vector = def_vector<gdb_byte>;
which is really the same as:
std::vector<gdb_byte, gdb::default_init_allocator<gdb_byte>>;
The intent then is to make "gdb::byte_vector" be the go-to for dynamic
byte buffers. So the less friction, the better.
#4 - Adjust current code to use it.
To set the example going forward. Replace std::vector uses and also
unique_ptr<byte[]> uses.
One nice thing is that with this allocator, for changes like these:
-std::unique_ptr<byte[]> buf (new gdb_byte[some_size]);
+gdb::byte_vector buf (some_size);
fill_with_data (buf.data (), buf.size ());
the generated code is the same as before. I.e., the compiler
de-structures the vector and gets rid of the unused "reserved vs size"
related fields.
The other nice thing is that it's easier to write
gdb::byte_vector buf (size);
than
std::unique_ptr<gdb_byte[]> buf (new gdb_byte[size]);
or even (C++14):
auto buf = std::make_unique<gdb_byte[]> (size); // zero-initializes...
#5 - Suggest s/std::vector<gdb_byte>/gdb::byte_vector/ going forward.
Note that this commit actually fixes a couple of bugs where the current
code is incorrectly using "std::vector::reserve(new_size)" and then
accessing the vector's internal buffer beyond the vector's size: see
dwarf2loc.c and charset.c. That's undefined behavior and may trigger
debug mode assertion failures. With default_init_allocator,
"resize()" behaves like "reserve()" performance wise, in that it
leaves new elements with unspecified values, but, it does that safely
without triggering undefined behavior when you access those values.
gdb/ChangeLog:
2017-06-14 Pedro Alves <palves@redhat.com>
* ada-lang.c: Include "common/byte-vector.h".
(ada_value_primitive_packed_val): Use gdb::byte_vector.
* charset.c (wchar_iterator::iterate): Resize the vector instead
of reserving it.
* common/byte-vector.h: Include "common/def-vector.h".
(wchar_iterator::m_out): Now a gdb::def_vector<gdb_wchar_t>.
* cli/cli-dump.c: Include "common/byte-vector.h".
(dump_memory_to_file, restore_binary_file): Use gdb::byte_vector.
* common/byte-vector.h: New file.
* common/def-vector.h: New file.
* common/default-init-alloc.h: New file.
* dwarf2loc.c: Include "common/byte-vector.h".
(rw_pieced_value): Use gdb::byte_vector, and resize the vector
instead of reserving it.
* dwarf2read.c: Include "common/byte-vector.h".
(data_buf::m_vec): Now a gdb::byte_vector.
* gdb_regex.c: Include "common/def-vector.h".
(compiled_regex::compiled_regex): Use gdb::def_vector<char>.
* mi/mi-main.c: Include "common/byte-vector.h".
(mi_cmd_data_read_memory): Use gdb::byte_vector.
* printcmd.c: Include "common/byte-vector.h".
(print_scalar_formatted): Use gdb::byte_vector.
* valprint.c: Include "common/byte-vector.h".
(maybe_negate_by_bytes, print_decimal_chars): Use
gdb::byte_vector.
Since read_pieced_value and write_pieced_value share significant logic,
this patch merges them into a single function rw_pieced_value.
gdb/ChangeLog:
* dwarf2loc.c (rw_pieced_value): New. Merge logic from...
(read_pieced_value, write_pieced_value): ...here. Reduce to
wrappers that just call rw_pieced_value.
So far write_pieced_value uses write_memory when writing memory pieces to
the target. However, this is a case where GDB potentially overwrites a
watchpoint value. In such a case write_memory_with_notification should be
used instead, so that memory_changed observers get notified.
gdb/ChangeLog:
* dwarf2loc.c (write_pieced_value): When writing the data for a
memory piece, use write_memory_with_notification instead of
write_memory.
In read_pieced_value's main loop, the variables `dest_offset_bits' and
`source_offset_bits' are basically just copies of `offset' and
`bits_to_skip', respectively. In write_pieced_value the copies are
reversed. This is not very helpful when trying to keep the logic between
these functions in sync. Since the copies are unnecessary, this patch
just removes them.
gdb/ChangeLog:
* dwarf2loc.c (read_pieced_value): Remove unnecessary variables
dest_offset_bits and source_offset_bits.
(write_pieced_value): Likewise.
So far GDB ignores the piece offset of all kinds of DWARF bit
pieces (DW_OP_bit_piece) and treats such pieces as if the offset was zero.
This is fixed, and an appropriate test is added.
gdb/ChangeLog:
* dwarf2loc.c (read_pieced_value): Respect the piece offset, as
given by DW_OP_bit_piece.
(write_pieced_value): Likewise.
Andreas Arnez <arnez@linux.vnet.ibm.com>
* gdb.dwarf2/var-access.exp: Add test for composite location with
nonzero piece offsets.
So far the main loop in read_pieced_value and write_pieced_value is
structured like this:
(1) Prepare a buffer and some variables we may need;
(2) depending on the DWARF piece type to be handled, use the buffer and
the prepared variables, ignore them, or even recalculate them.
This approach reduces readability and may also lead to unnecessary copying
of data. This patch moves the preparations to the places where sufficient
information is available and removes some of the variables involved.
gdb/ChangeLog:
* dwarf2loc.c (read_pieced_value): Move the buffer allocation and
some other preparations to the places where sufficient information
is available.
(write_pieced_value): Likewise.
For big-endian targets the logic in read/write_pieced_value tries to take
a register piece from the LSB end. This requires offsets and sizes to be
adjusted accordingly, and that's where the current implementation has some
issues:
* The formulas for recalculating the bit- and byte-offsets into the
register are wrong. They just happen to yield correct results if
everything is byte-aligned and the piece's last byte belongs to the
given value.
* After recalculating the bit offset into the register, the number of
bytes to be copied from the register is not recalculated. Of course
this does not matter if everything (particularly the piece size) is
byte-aligned.
These issues are fixed. The size calculation is performed with a new
helper function bits_to_bytes().
gdb/ChangeLog:
* dwarf2loc.c (bits_to_bytes): New function.
(read_pieced_value): Fix offset calculations for register pieces
on big-endian targets.
(write_pieced_value): Likewise.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/var-access.exp: Add test for non-byte-aligned
register pieces.
When the variable 'buffer_size' in read_pieced_value and
write_pieced_value was introduced, it was needed for tracking the buffer's
allocated size. Now that the buffer's data type has been changed to a
std::vector, the variable is no longer necessary; so remove it.
gdb/ChangeLog:
* dwarf2loc.c (read_pieced_value): Remove buffer_size variable.
(write_pieced_value): Likewise.
On big-endian targets, when targeting a bit-field, write_pieced_value
currently transfers the source value's *most* significant bits to the
target value, instead of its least significant bits. This is fixed.
In particular the fix adjusts the initial value of 'offset', which can now
potentially be nonzero. Thus the variable 'type_len' is renamed to
'max_offset', to avoid confusion. And for consistency, the affected logic
that was mirrored in read_pieced_value is changed there in the same way.
gdb/ChangeLog:
* dwarf2loc.c (write_pieced_value): When writing to a bit-field,
transfer the source value's least significant bits, instead of its
lowest-addressed ones. Rename type_len to max_offset.
(read_pieced_value): Mirror above changes to write_pieced_value as
applicable.
In write_pieced_value, when transferring the data to target memory via a
buffer, the bit offset within the target value is not reduced to its
sub-byte fraction before using it as a bit offset into the buffer. This
is fixed.
gdb/ChangeLog:
* dwarf2loc.c (write_pieced_value): In DWARF_VALUE_MEMORY,
truncate full bytes from dest_offset_bits before using it as an
offset into the buffer.
In write_pieced_value, when checking whether the data can be transferred
byte-wise, the current logic verifies the source- and destination offsets
to be byte-aligned, but not the transfer size. This is fixed.
gdb/ChangeLog:
* dwarf2loc.c (write_pieced_value): Include transfer size in
byte-wise check.
In write_pieced_value, the number of bytes containing a portion of the
bit-field in a given piece is calculated with the wrong starting offset;
thus the result may be off by one. This bug was probably introduced when
copying this logic from read_pieced_value. Fix it.
gdb/ChangeLog:
* dwarf2loc.c (write_pieced_value): Fix copy/paste error in the
calculation of this_size.
In the case of targeting a bit-field, read_pieced_value and
write_pieced_value calculate the number of bits preceding the bit-field
without considering the relative offset of the value's parent. This is
relevant for a structure variable like this:
struct s {
uint64_t foo;
struct {
uint32_t bar;
uint32_t bf : 10; /* <-- target bit-field */
} baz;
} s;
In this scenario, if 'val' is a GDB value representing s.baz.bf,
val->parent represents the whole s.baz structure, and the following holds:
- value_offset (val) == sizeof s.baz.bar == 4
- value_offset (val->parent) == sizeof s.foo == 8
The current logic would only use value_offset(val), resulting in the wrong
offset into the target value. This is fixed.
gdb/ChangeLog:
* dwarf2loc.c (read_pieced_value): Respect parent value's offset
when targeting a bit-field.
(write_pieced_value): Likewise.
The addr_size field in the piece_closure data structure is a relic from
before introducing the typed DWARF stack. It is obsolete now. This patch
removes it.
gdb/ChangeLog:
* dwarf2loc.c (struct piece_closure) <addr_size>: Remove field.
(allocate_piece_closure): Drop addr_size parameter.
(dwarf2_evaluate_loc_desc_full): Adjust call to
allocate_piece_closure.
When taking a DW_OP_piece or DW_OP_bit_piece from a DW_OP_stack_value, the
existing logic always takes the piece from the lowest-addressed end, which
is wrong on big-endian targets. The DWARF standard states that the
"DW_OP_bit_piece operation describes a sequence of bits using the least
significant bits of that value", and this also matches the current logic
in GCC. For instance, the GCC guality test case pr54970.c fails on s390x
because of this.
This fix adjusts the piece accordingly on big-endian targets. It is
assumed that:
* DW_OP_piece shall take the piece from the LSB end as well;
* pieces reaching outside the stack value bits are considered undefined,
and a zero value can be used instead.
gdb/ChangeLog:
PR gdb/21226
* dwarf2loc.c (read_pieced_value): Anchor stack value pieces at
the LSB end, independent of endianness.
gdb/testsuite/ChangeLog:
PR gdb/21226
* gdb.dwarf2/nonvar-access.exp: Add checks for verifying that
stack value pieces are taken from the LSB end.
A field f in a structure composed of DWARF pieces may be located in
multiple pieces, where the first and last of those may contain bits from
other fields as well. So when writing to f, the beginning of the first
and the end of the last of those pieces may have to be skipped. But the
logic in write_pieced_value for handling one of those pieces is flawed
when the first and last piece are the same, i.e., f is contained in a
single piece:
< - - - - - - - - - piece_size - - - - - - - - - ->
+-------------------------------------------------+
| skipped_bits | f_bits | / / / / / / / / / / |
+-------------------------------------------------+
The current logic determines the size of the sub-piece to operate on by
limiting the piece size to the bit size of f and then subtracting the
skipped bits:
min (piece_size, f_bits) - skipped_bits
Instead of:
min (piece_size - skipped_bits, f_bits)
So the resulting sub-piece size is corrupted, leading to wrong handling of
this piece in write_pieced_value.
Note that the same bug was already found in read_pieced_value and fixed
there (but not in write_pieced_value), see PR 15391.
This patch swaps the calculations, bringing them into the same (correct)
order as in read_pieced_value.
gdb/ChangeLog:
* dwarf2loc.c (write_pieced_value): Fix order of calculations for
size capping.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/var-pieces.exp: Add test case for modifying a
variable at nonzero offset.