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darling-gdb/gdb/cp-abi.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

415 lines
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/* Generic code for supporting multiple C++ ABI's
Copyright (C) 2001-2015 Free Software Foundation, Inc.
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 "value.h"
#include "cp-abi.h"
#include "command.h"
#include "gdbcmd.h"
#include "ui-out.h"
static struct cp_abi_ops *find_cp_abi (const char *short_name);
static struct cp_abi_ops current_cp_abi = { "", NULL };
static struct cp_abi_ops auto_cp_abi = { "auto", NULL };
#define CP_ABI_MAX 8
static struct cp_abi_ops *cp_abis[CP_ABI_MAX];
static int num_cp_abis = 0;
enum ctor_kinds
is_constructor_name (const char *name)
{
if ((current_cp_abi.is_constructor_name) == NULL)
error (_("ABI doesn't define required function is_constructor_name"));
return (*current_cp_abi.is_constructor_name) (name);
}
enum dtor_kinds
is_destructor_name (const char *name)
{
if ((current_cp_abi.is_destructor_name) == NULL)
error (_("ABI doesn't define required function is_destructor_name"));
return (*current_cp_abi.is_destructor_name) (name);
}
int
is_vtable_name (const char *name)
{
if ((current_cp_abi.is_vtable_name) == NULL)
error (_("ABI doesn't define required function is_vtable_name"));
return (*current_cp_abi.is_vtable_name) (name);
}
int
is_operator_name (const char *name)
{
if ((current_cp_abi.is_operator_name) == NULL)
error (_("ABI doesn't define required function is_operator_name"));
return (*current_cp_abi.is_operator_name) (name);
}
int
baseclass_offset (struct type *type, int index, const gdb_byte *valaddr,
int embedded_offset, CORE_ADDR address,
const struct value *val)
{
int res = 0;
gdb_assert (current_cp_abi.baseclass_offset != NULL);
TRY
{
res = (*current_cp_abi.baseclass_offset) (type, index, valaddr,
embedded_offset,
address, val);
}
CATCH (ex, RETURN_MASK_ERROR)
{
if (ex.error != NOT_AVAILABLE_ERROR)
throw_exception (ex);
throw_error (NOT_AVAILABLE_ERROR,
_("Cannot determine virtual baseclass offset "
"of incomplete object"));
}
END_CATCH
return res;
}
struct value *
value_virtual_fn_field (struct value **arg1p,
struct fn_field *f, int j,
struct type *type, int offset)
{
if ((current_cp_abi.virtual_fn_field) == NULL)
return NULL;
return (*current_cp_abi.virtual_fn_field) (arg1p, f, j,
type, offset);
}
struct type *
value_rtti_type (struct value *v, int *full,
int *top, int *using_enc)
{
struct type *ret = NULL;
if ((current_cp_abi.rtti_type) == NULL)
return NULL;
TRY
{
ret = (*current_cp_abi.rtti_type) (v, full, top, using_enc);
}
CATCH (e, RETURN_MASK_ERROR)
{
return NULL;
}
END_CATCH
return ret;
}
void
cplus_print_method_ptr (const gdb_byte *contents,
struct type *type,
struct ui_file *stream)
{
if (current_cp_abi.print_method_ptr == NULL)
error (_("GDB does not support pointers to methods on this target"));
(*current_cp_abi.print_method_ptr) (contents, type, stream);
}
int
cplus_method_ptr_size (struct type *to_type)
{
if (current_cp_abi.method_ptr_size == NULL)
error (_("GDB does not support pointers to methods on this target"));
return (*current_cp_abi.method_ptr_size) (to_type);
}
void
cplus_make_method_ptr (struct type *type, gdb_byte *contents,
CORE_ADDR value, int is_virtual)
{
if (current_cp_abi.make_method_ptr == NULL)
error (_("GDB does not support pointers to methods on this target"));
(*current_cp_abi.make_method_ptr) (type, contents, value, is_virtual);
}
CORE_ADDR
cplus_skip_trampoline (struct frame_info *frame,
CORE_ADDR stop_pc)
{
if (current_cp_abi.skip_trampoline == NULL)
return 0;
return (*current_cp_abi.skip_trampoline) (frame, stop_pc);
}
struct value *
cplus_method_ptr_to_value (struct value **this_p,
struct value *method_ptr)
{
if (current_cp_abi.method_ptr_to_value == NULL)
error (_("GDB does not support pointers to methods on this target"));
return (*current_cp_abi.method_ptr_to_value) (this_p, method_ptr);
}
/* See cp-abi.h. */
void
cplus_print_vtable (struct value *value)
{
if (current_cp_abi.print_vtable == NULL)
error (_("GDB cannot print the vtable on this target"));
(*current_cp_abi.print_vtable) (value);
}
/* See cp-abi.h. */
struct value *
cplus_typeid (struct value *value)
{
if (current_cp_abi.get_typeid == NULL)
error (_("GDB cannot find the typeid on this target"));
return (*current_cp_abi.get_typeid) (value);
}
/* See cp-abi.h. */
struct type *
cplus_typeid_type (struct gdbarch *gdbarch)
{
if (current_cp_abi.get_typeid_type == NULL)
error (_("GDB cannot find the type for 'typeid' on this target"));
return (*current_cp_abi.get_typeid_type) (gdbarch);
}
/* See cp-abi.h. */
struct type *
cplus_type_from_type_info (struct value *value)
{
if (current_cp_abi.get_type_from_type_info == NULL)
error (_("GDB cannot find the type from a std::type_info on this target"));
return (*current_cp_abi.get_type_from_type_info) (value);
}
/* See cp-abi.h. */
char *
cplus_typename_from_type_info (struct value *value)
{
if (current_cp_abi.get_typename_from_type_info == NULL)
error (_("GDB cannot find the type name "
"from a std::type_info on this target"));
return (*current_cp_abi.get_typename_from_type_info) (value);
}
int
cp_pass_by_reference (struct type *type)
{
if ((current_cp_abi.pass_by_reference) == NULL)
return 0;
return (*current_cp_abi.pass_by_reference) (type);
}
/* Set the current C++ ABI to SHORT_NAME. */
static int
switch_to_cp_abi (const char *short_name)
{
struct cp_abi_ops *abi;
abi = find_cp_abi (short_name);
if (abi == NULL)
return 0;
current_cp_abi = *abi;
return 1;
}
/* Add ABI to the list of supported C++ ABI's. */
int
register_cp_abi (struct cp_abi_ops *abi)
{
if (num_cp_abis == CP_ABI_MAX)
internal_error (__FILE__, __LINE__,
_("Too many C++ ABIs, please increase "
"CP_ABI_MAX in cp-abi.c"));
cp_abis[num_cp_abis++] = abi;
return 1;
}
/* Set the ABI to use in "auto" mode to SHORT_NAME. */
void
set_cp_abi_as_auto_default (const char *short_name)
{
char *new_longname, *new_doc;
struct cp_abi_ops *abi = find_cp_abi (short_name);
if (abi == NULL)
internal_error (__FILE__, __LINE__,
_("Cannot find C++ ABI \"%s\" to set it as auto default."),
short_name);
if (auto_cp_abi.longname != NULL)
xfree ((char *) auto_cp_abi.longname);
if (auto_cp_abi.doc != NULL)
xfree ((char *) auto_cp_abi.doc);
auto_cp_abi = *abi;
auto_cp_abi.shortname = "auto";
new_longname = xstrprintf ("currently \"%s\"", abi->shortname);
auto_cp_abi.longname = new_longname;
new_doc = xstrprintf ("Automatically selected; currently \"%s\"",
abi->shortname);
auto_cp_abi.doc = new_doc;
/* Since we copy the current ABI into current_cp_abi instead of
using a pointer, if auto is currently the default, we need to
reset it. */
if (strcmp (current_cp_abi.shortname, "auto") == 0)
switch_to_cp_abi ("auto");
}
/* Return the ABI operations associated with SHORT_NAME. */
static struct cp_abi_ops *
find_cp_abi (const char *short_name)
{
int i;
for (i = 0; i < num_cp_abis; i++)
if (strcmp (cp_abis[i]->shortname, short_name) == 0)
return cp_abis[i];
return NULL;
}
/* Display the list of registered C++ ABIs. */
static void
list_cp_abis (int from_tty)
{
struct ui_out *uiout = current_uiout;
struct cleanup *cleanup_chain;
int i;
ui_out_text (uiout, "The available C++ ABIs are:\n");
cleanup_chain = make_cleanup_ui_out_tuple_begin_end (uiout,
"cp-abi-list");
for (i = 0; i < num_cp_abis; i++)
{
char pad[14];
int padcount;
ui_out_text (uiout, " ");
ui_out_field_string (uiout, "cp-abi", cp_abis[i]->shortname);
padcount = 16 - 2 - strlen (cp_abis[i]->shortname);
pad[padcount] = 0;
while (padcount > 0)
pad[--padcount] = ' ';
ui_out_text (uiout, pad);
ui_out_field_string (uiout, "doc", cp_abis[i]->doc);
ui_out_text (uiout, "\n");
}
do_cleanups (cleanup_chain);
}
/* Set the current C++ ABI, or display the list of options if no
argument is given. */
static void
set_cp_abi_cmd (char *args, int from_tty)
{
if (args == NULL)
{
list_cp_abis (from_tty);
return;
}
if (!switch_to_cp_abi (args))
error (_("Could not find \"%s\" in ABI list"), args);
}
/* A completion function for "set cp-abi". */
static VEC (char_ptr) *
cp_abi_completer (struct cmd_list_element *ignore,
const char *text, const char *word)
{
static const char **cp_abi_names;
if (cp_abi_names == NULL)
{
int i;
cp_abi_names = XNEWVEC (const char *, num_cp_abis + 1);
for (i = 0; i < num_cp_abis; ++i)
cp_abi_names[i] = cp_abis[i]->shortname;
cp_abi_names[i] = NULL;
}
return complete_on_enum (cp_abi_names, text, word);
}
/* Show the currently selected C++ ABI. */
static void
show_cp_abi_cmd (char *args, int from_tty)
{
struct ui_out *uiout = current_uiout;
ui_out_text (uiout, "The currently selected C++ ABI is \"");
ui_out_field_string (uiout, "cp-abi", current_cp_abi.shortname);
ui_out_text (uiout, "\" (");
ui_out_field_string (uiout, "longname", current_cp_abi.longname);
ui_out_text (uiout, ").\n");
}
extern initialize_file_ftype _initialize_cp_abi; /* -Wmissing-prototypes */
void
_initialize_cp_abi (void)
{
struct cmd_list_element *c;
register_cp_abi (&auto_cp_abi);
switch_to_cp_abi ("auto");
c = add_cmd ("cp-abi", class_obscure, set_cp_abi_cmd, _("\
Set the ABI used for inspecting C++ objects.\n\
\"set cp-abi\" with no arguments will list the available ABIs."),
&setlist);
set_cmd_completer (c, cp_abi_completer);
add_cmd ("cp-abi", class_obscure, show_cp_abi_cmd,
_("Show the ABI used for inspecting C++ objects."),
&showlist);
}
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