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binutils-gdb/gdb/mi/mi-cmd-stack.c
Pedro Alves 492d29ea1c Split TRY_CATCH into TRY + CATCH 
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.
2015-03-07 15:14:14 +00:00

714 lines
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/* MI Command Set - stack commands.
Copyright (C) 2000-2015 Free Software Foundation, Inc.
Contributed by Cygnus Solutions (a Red Hat company).
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "target.h"
#include "frame.h"
#include "value.h"
#include "mi-cmds.h"
#include "ui-out.h"
#include "symtab.h"
#include "block.h"
#include "stack.h"
#include "dictionary.h"
#include "language.h"
#include "valprint.h"
#include "utils.h"
#include "mi-getopt.h"
#include "extension.h"
#include <ctype.h>
#include "mi-parse.h"
enum what_to_list { locals, arguments, all };
static void list_args_or_locals (enum what_to_list what,
enum print_values values,
struct frame_info *fi,
int skip_unavailable);
/* True if we want to allow Python-based frame filters. */
static int frame_filters = 0;
void
mi_cmd_enable_frame_filters (char *command, char **argv, int argc)
{
if (argc != 0)
error (_("-enable-frame-filters: no arguments allowed"));
frame_filters = 1;
}
/* Like apply_ext_lang_frame_filter, but take a print_values */
static enum ext_lang_bt_status
mi_apply_ext_lang_frame_filter (struct frame_info *frame, int flags,
enum print_values print_values,
struct ui_out *out,
int frame_low, int frame_high)
{
/* ext_lang_frame_args's MI options are compatible with MI print
values. */
return apply_ext_lang_frame_filter (frame, flags,
(enum ext_lang_frame_args) print_values,
out,
frame_low, frame_high);
}
/* Print a list of the stack frames. Args can be none, in which case
we want to print the whole backtrace, or a pair of numbers
specifying the frame numbers at which to start and stop the
display. If the two numbers are equal, a single frame will be
displayed. */
void
mi_cmd_stack_list_frames (char *command, char **argv, int argc)
{
int frame_low;
int frame_high;
int i;
struct cleanup *cleanup_stack;
struct frame_info *fi;
enum ext_lang_bt_status result = EXT_LANG_BT_ERROR;
int raw_arg = 0;
int oind = 0;
enum opt
{
NO_FRAME_FILTERS
};
static const struct mi_opt opts[] =
{
{"-no-frame-filters", NO_FRAME_FILTERS, 0},
{ 0, 0, 0 }
};
/* Parse arguments. In this instance we are just looking for
--no-frame-filters. */
while (1)
{
char *oarg;
int opt = mi_getopt ("-stack-list-frames", argc, argv,
opts, &oind, &oarg);
if (opt < 0)
break;
switch ((enum opt) opt)
{
case NO_FRAME_FILTERS:
raw_arg = oind;
break;
}
}
/* After the last option is parsed, there should either be low -
high range, or no further arguments. */
if ((argc - oind != 0) && (argc - oind != 2))
error (_("-stack-list-frames: Usage: [--no-frame-filters] [FRAME_LOW FRAME_HIGH]"));
/* If there is a range, set it. */
if (argc - oind == 2)
{
frame_low = atoi (argv[0 + oind]);
frame_high = atoi (argv[1 + oind]);
}
else
{
/* Called with no arguments, it means we want the whole
backtrace. */
frame_low = -1;
frame_high = -1;
}
/* Let's position fi on the frame at which to start the
display. Could be the innermost frame if the whole stack needs
displaying, or if frame_low is 0. */
for (i = 0, fi = get_current_frame ();
fi && i < frame_low;
i++, fi = get_prev_frame (fi));
if (fi == NULL)
error (_("-stack-list-frames: Not enough frames in stack."));
cleanup_stack = make_cleanup_ui_out_list_begin_end (current_uiout, "stack");
if (! raw_arg && frame_filters)
{
int flags = PRINT_LEVEL | PRINT_FRAME_INFO;
int py_frame_low = frame_low;
/* We cannot pass -1 to frame_low, as that would signify a
relative backtrace from the tail of the stack. So, in the case
of frame_low == -1, assign and increment it. */
if (py_frame_low == -1)
py_frame_low++;
result = apply_ext_lang_frame_filter (get_current_frame (), flags,
NO_VALUES, current_uiout,
py_frame_low, frame_high);
}
/* Run the inbuilt backtrace if there are no filters registered, or
if "--no-frame-filters" has been specified from the command. */
if (! frame_filters || raw_arg || result == EXT_LANG_BT_NO_FILTERS)
{
/* Now let's print the frames up to frame_high, or until there are
frames in the stack. */
for (;
fi && (i <= frame_high || frame_high == -1);
i++, fi = get_prev_frame (fi))
{
QUIT;
/* Print the location and the address always, even for level 0.
If args is 0, don't print the arguments. */
print_frame_info (fi, 1, LOC_AND_ADDRESS, 0 /* args */, 0);
}
}
do_cleanups (cleanup_stack);
}
void
mi_cmd_stack_info_depth (char *command, char **argv, int argc)
{
int frame_high;
int i;
struct frame_info *fi;
if (argc > 1)
error (_("-stack-info-depth: Usage: [MAX_DEPTH]"));
if (argc == 1)
frame_high = atoi (argv[0]);
else
/* Called with no arguments, it means we want the real depth of
the stack. */
frame_high = -1;
for (i = 0, fi = get_current_frame ();
fi && (i < frame_high || frame_high == -1);
i++, fi = get_prev_frame (fi))
QUIT;
ui_out_field_int (current_uiout, "depth", i);
}
/* Print a list of the locals for the current frame. With argument of
0, print only the names, with argument of 1 print also the
values. */
void
mi_cmd_stack_list_locals (char *command, char **argv, int argc)
{
struct frame_info *frame;
int raw_arg = 0;
enum ext_lang_bt_status result = EXT_LANG_BT_ERROR;
int print_value;
int oind = 0;
int skip_unavailable = 0;
int i;
if (argc > 1)
{
int i;
enum opt
{
NO_FRAME_FILTERS,
SKIP_UNAVAILABLE,
};
static const struct mi_opt opts[] =
{
{"-no-frame-filters", NO_FRAME_FILTERS, 0},
{"-skip-unavailable", SKIP_UNAVAILABLE, 0},
{ 0, 0, 0 }
};
while (1)
{
char *oarg;
/* Don't parse 'print-values' as an option. */
int opt = mi_getopt ("-stack-list-locals", argc - 1, argv,
opts, &oind, &oarg);
if (opt < 0)
break;
switch ((enum opt) opt)
{
case NO_FRAME_FILTERS:
raw_arg = oind;
case SKIP_UNAVAILABLE:
skip_unavailable = 1;
break;
}
}
}
/* After the last option is parsed, there should be only
'print-values'. */
if (argc - oind != 1)
error (_("-stack-list-locals: Usage: [--no-frame-filters] "
"[--skip-unavailable] PRINT_VALUES"));
frame = get_selected_frame (NULL);
print_value = mi_parse_print_values (argv[oind]);
if (! raw_arg && frame_filters)
{
int flags = PRINT_LEVEL | PRINT_LOCALS;
result = mi_apply_ext_lang_frame_filter (frame, flags, print_value,
current_uiout, 0, 0);
}
/* Run the inbuilt backtrace if there are no filters registered, or
if "--no-frame-filters" has been specified from the command. */
if (! frame_filters || raw_arg || result == EXT_LANG_BT_NO_FILTERS)
{
list_args_or_locals (locals, print_value, frame,
skip_unavailable);
}
}
/* Print a list of the arguments for the current frame. With argument
of 0, print only the names, with argument of 1 print also the
values. */
void
mi_cmd_stack_list_args (char *command, char **argv, int argc)
{
int frame_low;
int frame_high;
int i;
struct frame_info *fi;
struct cleanup *cleanup_stack_args;
enum print_values print_values;
struct ui_out *uiout = current_uiout;
int raw_arg = 0;
int oind = 0;
int skip_unavailable = 0;
enum ext_lang_bt_status result = EXT_LANG_BT_ERROR;
enum opt
{
NO_FRAME_FILTERS,
SKIP_UNAVAILABLE,
};
static const struct mi_opt opts[] =
{
{"-no-frame-filters", NO_FRAME_FILTERS, 0},
{"-skip-unavailable", SKIP_UNAVAILABLE, 0},
{ 0, 0, 0 }
};
while (1)
{
char *oarg;
int opt = mi_getopt_allow_unknown ("-stack-list-args", argc, argv,
opts, &oind, &oarg);
if (opt < 0)
break;
switch ((enum opt) opt)
{
case NO_FRAME_FILTERS:
raw_arg = oind;
break;
case SKIP_UNAVAILABLE:
skip_unavailable = 1;
break;
}
}
if (argc - oind != 1 && argc - oind != 3)
error (_("-stack-list-arguments: Usage: " \
"[--no-frame-filters] [--skip-unavailable] "
"PRINT_VALUES [FRAME_LOW FRAME_HIGH]"));
if (argc - oind == 3)
{
frame_low = atoi (argv[1 + oind]);
frame_high = atoi (argv[2 + oind]);
}
else
{
/* Called with no arguments, it means we want args for the whole
backtrace. */
frame_low = -1;
frame_high = -1;
}
print_values = mi_parse_print_values (argv[oind]);
/* Let's position fi on the frame at which to start the
display. Could be the innermost frame if the whole stack needs
displaying, or if frame_low is 0. */
for (i = 0, fi = get_current_frame ();
fi && i < frame_low;
i++, fi = get_prev_frame (fi));
if (fi == NULL)
error (_("-stack-list-arguments: Not enough frames in stack."));
cleanup_stack_args
= make_cleanup_ui_out_list_begin_end (uiout, "stack-args");
if (! raw_arg && frame_filters)
{
int flags = PRINT_LEVEL | PRINT_ARGS;
int py_frame_low = frame_low;
/* We cannot pass -1 to frame_low, as that would signify a
relative backtrace from the tail of the stack. So, in the case
of frame_low == -1, assign and increment it. */
if (py_frame_low == -1)
py_frame_low++;
result = mi_apply_ext_lang_frame_filter (get_current_frame (), flags,
print_values, current_uiout,
py_frame_low, frame_high);
}
/* Run the inbuilt backtrace if there are no filters registered, or
if "--no-frame-filters" has been specified from the command. */
if (! frame_filters || raw_arg || result == EXT_LANG_BT_NO_FILTERS)
{
/* Now let's print the frames up to frame_high, or until there are
frames in the stack. */
for (;
fi && (i <= frame_high || frame_high == -1);
i++, fi = get_prev_frame (fi))
{
struct cleanup *cleanup_frame;
QUIT;
cleanup_frame = make_cleanup_ui_out_tuple_begin_end (uiout, "frame");
ui_out_field_int (uiout, "level", i);
list_args_or_locals (arguments, print_values, fi, skip_unavailable);
do_cleanups (cleanup_frame);
}
}
do_cleanups (cleanup_stack_args);
}
/* Print a list of the local variables (including arguments) for the
current frame. ARGC must be 1 and ARGV[0] specify if only the names,
or both names and values of the variables must be printed. See
parse_print_value for possible values. */
void
mi_cmd_stack_list_variables (char *command, char **argv, int argc)
{
struct frame_info *frame;
int raw_arg = 0;
enum ext_lang_bt_status result = EXT_LANG_BT_ERROR;
int print_value;
int oind = 0;
int skip_unavailable = 0;
if (argc > 1)
{
int i;
enum opt
{
NO_FRAME_FILTERS,
SKIP_UNAVAILABLE,
};
static const struct mi_opt opts[] =
{
{"-no-frame-filters", NO_FRAME_FILTERS, 0},
{"-skip-unavailable", SKIP_UNAVAILABLE, 0},
{ 0, 0, 0 }
};
while (1)
{
char *oarg;
/* Don't parse 'print-values' as an option. */
int opt = mi_getopt ("-stack-list-variables", argc - 1,
argv, opts, &oind, &oarg);
if (opt < 0)
break;
switch ((enum opt) opt)
{
case NO_FRAME_FILTERS:
raw_arg = oind;
break;
case SKIP_UNAVAILABLE:
skip_unavailable = 1;
break;
}
}
}
/* After the last option is parsed, there should be only
'print-values'. */
if (argc - oind != 1)
error (_("-stack-list-variables: Usage: [--no-frame-filters] " \
"[--skip-unavailable] PRINT_VALUES"));
frame = get_selected_frame (NULL);
print_value = mi_parse_print_values (argv[oind]);
if (! raw_arg && frame_filters)
{
int flags = PRINT_LEVEL | PRINT_ARGS | PRINT_LOCALS;
result = mi_apply_ext_lang_frame_filter (frame, flags,
print_value,
current_uiout, 0, 0);
}
/* Run the inbuilt backtrace if there are no filters registered, or
if "--no-frame-filters" has been specified from the command. */
if (! frame_filters || raw_arg || result == EXT_LANG_BT_NO_FILTERS)
{
list_args_or_locals (all, print_value, frame,
skip_unavailable);
}
}
/* Print single local or argument. ARG must be already read in. For
WHAT and VALUES see list_args_or_locals.
Errors are printed as if they would be the parameter value. Use
zeroed ARG iff it should not be printed according to VALUES. If
SKIP_UNAVAILABLE is true, only print ARG if it is available. */
static void
list_arg_or_local (const struct frame_arg *arg, enum what_to_list what,
enum print_values values, int skip_unavailable)
{
struct cleanup *old_chain;
struct ui_out *uiout = current_uiout;
struct ui_file *stb;
gdb_assert (!arg->val || !arg->error);
gdb_assert ((values == PRINT_NO_VALUES && arg->val == NULL
&& arg->error == NULL)
|| values == PRINT_SIMPLE_VALUES
|| (values == PRINT_ALL_VALUES
&& (arg->val != NULL || arg->error != NULL)));
gdb_assert (arg->entry_kind == print_entry_values_no
|| (arg->entry_kind == print_entry_values_only
&& (arg->val || arg->error)));
if (skip_unavailable && arg->val != NULL
&& (value_entirely_unavailable (arg->val)
/* A scalar object that does not have all bits available is
also considered unavailable, because all bits contribute
to its representation. */
|| (val_print_scalar_type_p (value_type (arg->val))
&& !value_bytes_available (arg->val,
value_embedded_offset (arg->val),
TYPE_LENGTH (value_type (arg->val))))))
return;
stb = mem_fileopen ();
old_chain = make_cleanup_ui_file_delete (stb);
if (values != PRINT_NO_VALUES || what == all)
make_cleanup_ui_out_tuple_begin_end (uiout, NULL);
fputs_filtered (SYMBOL_PRINT_NAME (arg->sym), stb);
if (arg->entry_kind == print_entry_values_only)
fputs_filtered ("@entry", stb);
ui_out_field_stream (uiout, "name", stb);
if (what == all && SYMBOL_IS_ARGUMENT (arg->sym))
ui_out_field_int (uiout, "arg", 1);
if (values == PRINT_SIMPLE_VALUES)
{
check_typedef (arg->sym->type);
type_print (arg->sym->type, "", stb, -1);
ui_out_field_stream (uiout, "type", stb);
}
if (arg->val || arg->error)
{
const char *error_message = NULL;
if (arg->error)
error_message = arg->error;
else
{
TRY
{
struct value_print_options opts;
get_no_prettyformat_print_options (&opts);
opts.deref_ref = 1;
common_val_print (arg->val, stb, 0, &opts,
language_def (SYMBOL_LANGUAGE (arg->sym)));
}
CATCH (except, RETURN_MASK_ERROR)
{
error_message = except.message;
}
END_CATCH
}
if (error_message != NULL)
fprintf_filtered (stb, _("<error reading variable: %s>"),
error_message);
ui_out_field_stream (uiout, "value", stb);
}
do_cleanups (old_chain);
}
/* Print a list of the objects for the frame FI in a certain form,
which is determined by VALUES. The objects can be locals,
arguments or both, which is determined by WHAT. If SKIP_UNAVAILABLE
is true, only print the arguments or local variables whose values
are available. */
static void
list_args_or_locals (enum what_to_list what, enum print_values values,
struct frame_info *fi, int skip_unavailable)
{
const struct block *block;
struct symbol *sym;
struct block_iterator iter;
struct cleanup *cleanup_list;
struct type *type;
char *name_of_result;
struct ui_out *uiout = current_uiout;
block = get_frame_block (fi, 0);
switch (what)
{
case locals:
name_of_result = "locals";
break;
case arguments:
name_of_result = "args";
break;
case all:
name_of_result = "variables";
break;
default:
internal_error (__FILE__, __LINE__,
"unexpected what_to_list: %d", (int) what);
}
cleanup_list = make_cleanup_ui_out_list_begin_end (uiout, name_of_result);
while (block != 0)
{
ALL_BLOCK_SYMBOLS (block, iter, sym)
{
int print_me = 0;
switch (SYMBOL_CLASS (sym))
{
default:
case LOC_UNDEF: /* catches errors */
case LOC_CONST: /* constant */
case LOC_TYPEDEF: /* local typedef */
case LOC_LABEL: /* local label */
case LOC_BLOCK: /* local function */
case LOC_CONST_BYTES: /* loc. byte seq. */
case LOC_UNRESOLVED: /* unresolved static */
case LOC_OPTIMIZED_OUT: /* optimized out */
print_me = 0;
break;
case LOC_ARG: /* argument */
case LOC_REF_ARG: /* reference arg */
case LOC_REGPARM_ADDR: /* indirect register arg */
case LOC_LOCAL: /* stack local */
case LOC_STATIC: /* static */
case LOC_REGISTER: /* register */
case LOC_COMPUTED: /* computed location */
if (what == all)
print_me = 1;
else if (what == locals)
print_me = !SYMBOL_IS_ARGUMENT (sym);
else
print_me = SYMBOL_IS_ARGUMENT (sym);
break;
}
if (print_me)
{
struct symbol *sym2;
struct frame_arg arg, entryarg;
if (SYMBOL_IS_ARGUMENT (sym))
sym2 = lookup_symbol (SYMBOL_LINKAGE_NAME (sym),
block, VAR_DOMAIN,
NULL);
else
sym2 = sym;
gdb_assert (sym2 != NULL);
memset (&arg, 0, sizeof (arg));
arg.sym = sym2;
arg.entry_kind = print_entry_values_no;
memset (&entryarg, 0, sizeof (entryarg));
entryarg.sym = sym2;
entryarg.entry_kind = print_entry_values_no;
switch (values)
{
case PRINT_SIMPLE_VALUES:
type = check_typedef (sym2->type);
if (TYPE_CODE (type) != TYPE_CODE_ARRAY
&& TYPE_CODE (type) != TYPE_CODE_STRUCT
&& TYPE_CODE (type) != TYPE_CODE_UNION)
{
case PRINT_ALL_VALUES:
if (SYMBOL_IS_ARGUMENT (sym))
read_frame_arg (sym2, fi, &arg, &entryarg);
else
read_frame_local (sym2, fi, &arg);
}
break;
}
if (arg.entry_kind != print_entry_values_only)
list_arg_or_local (&arg, what, values, skip_unavailable);
if (entryarg.entry_kind != print_entry_values_no)
list_arg_or_local (&entryarg, what, values, skip_unavailable);
xfree (arg.error);
xfree (entryarg.error);
}
}
if (BLOCK_FUNCTION (block))
break;
else
block = BLOCK_SUPERBLOCK (block);
}
do_cleanups (cleanup_list);
}
void
mi_cmd_stack_select_frame (char *command, char **argv, int argc)
{
if (argc == 0 || argc > 1)
error (_("-stack-select-frame: Usage: FRAME_SPEC"));
select_frame_command (argv[0], 1 /* not used */ );
}
void
mi_cmd_stack_info_frame (char *command, char **argv, int argc)
{
if (argc > 0)
error (_("-stack-info-frame: No arguments allowed"));
print_frame_info (get_selected_frame (NULL), 1, LOC_AND_ADDRESS, 0, 1);
}
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