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8480a37e14
We currently pass frames to function by value, as `frame_info_ptr`.
This is somewhat expensive:
- the size of `frame_info_ptr` is 64 bytes, which is a bit big to pass
by value
- the constructors and destructor link/unlink the object in the global
`frame_info_ptr::frame_list` list. This is an `intrusive_list`, so
it's not so bad: it's just assigning a few points, there's no memory
allocation as if it was `std::list`, but still it's useless to do
that over and over.
As suggested by Tom Tromey, change many function signatures to accept
`const frame_info_ptr &` instead of `frame_info_ptr`.
Some functions reassign their `frame_info_ptr` parameter, like:
void
the_func (frame_info_ptr frame)
{
for (; frame != nullptr; frame = get_prev_frame (frame))
{
...
}
}
I wondered what to do about them, do I leave them as-is or change them
(and need to introduce a separate local variable that can be
re-assigned). I opted for the later for consistency. It might not be
clear why some functions take `const frame_info_ptr &` while others take
`frame_info_ptr`. Also, if a function took a `frame_info_ptr` because
it did re-assign its parameter, I doubt that we would think to change it
to `const frame_info_ptr &` should the implementation change such that
it doesn't need to take `frame_info_ptr` anymore. It seems better to
have a simple rule and apply it everywhere.
Change-Id: I59d10addef687d157f82ccf4d54f5dde9a963fd0
Approved-By: Andrew Burgess <aburgess@redhat.com>
109 lines
3.8 KiB
C
109 lines
3.8 KiB
C
/* Builtin frame register, for GDB, the GNU debugger.
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Copyright (C) 2002-2024 Free Software Foundation, Inc.
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Contributed by Red Hat.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "user-regs.h"
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#include "frame.h"
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#include "gdbtypes.h"
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#include "value.h"
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#include "gdbarch.h"
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static struct value *
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value_of_builtin_frame_fp_reg (const frame_info_ptr &frame, const void *baton)
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{
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struct gdbarch *gdbarch = get_frame_arch (frame);
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if (gdbarch_deprecated_fp_regnum (gdbarch) >= 0)
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/* NOTE: cagney/2003-04-24: Since the mere presence of "fp" in the
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register name table overrides this built-in $fp register, there
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is no real reason for this gdbarch_deprecated_fp_regnum trickery here.
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An architecture wanting to implement "$fp" as alias for a raw
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register can do so by adding "fp" to register name table (mind
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you, doing this is probably a dangerous thing). */
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return value_of_register (gdbarch_deprecated_fp_regnum (gdbarch),
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get_next_frame_sentinel_okay (frame));
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else
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{
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struct type *data_ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
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struct value *val = value::allocate (data_ptr_type);
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gdb_byte *buf = val->contents_raw ().data ();
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gdbarch_address_to_pointer (gdbarch, data_ptr_type,
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buf, get_frame_base_address (frame));
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return val;
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}
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}
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static struct value *
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value_of_builtin_frame_pc_reg (const frame_info_ptr &frame, const void *baton)
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{
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struct gdbarch *gdbarch = get_frame_arch (frame);
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if (gdbarch_pc_regnum (gdbarch) >= 0)
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return value_of_register (gdbarch_pc_regnum (gdbarch),
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get_next_frame_sentinel_okay (frame));
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else
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{
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struct type *func_ptr_type = builtin_type (gdbarch)->builtin_func_ptr;
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struct value *val = value::allocate (func_ptr_type);
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gdb_byte *buf = val->contents_raw ().data ();
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gdbarch_address_to_pointer (gdbarch, func_ptr_type,
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buf, get_frame_pc (frame));
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return val;
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}
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}
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static struct value *
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value_of_builtin_frame_sp_reg (const frame_info_ptr &frame, const void *baton)
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{
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struct gdbarch *gdbarch = get_frame_arch (frame);
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if (gdbarch_sp_regnum (gdbarch) >= 0)
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return value_of_register (gdbarch_sp_regnum (gdbarch),
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get_next_frame_sentinel_okay (frame));
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error (_("Standard register ``$sp'' is not available for this target"));
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}
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static struct value *
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value_of_builtin_frame_ps_reg (const frame_info_ptr &frame, const void *baton)
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{
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struct gdbarch *gdbarch = get_frame_arch (frame);
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if (gdbarch_ps_regnum (gdbarch) >= 0)
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return value_of_register (gdbarch_ps_regnum (gdbarch),
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get_next_frame_sentinel_okay (frame));
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error (_("Standard register ``$ps'' is not available for this target"));
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}
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void _initialize_frame_reg ();
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void
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_initialize_frame_reg ()
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{
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/* Frame based $fp, $pc, $sp and $ps. These only come into play
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when the target does not define its own version of these
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registers. */
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user_reg_add_builtin ("fp", value_of_builtin_frame_fp_reg, NULL);
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user_reg_add_builtin ("pc", value_of_builtin_frame_pc_reg, NULL);
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user_reg_add_builtin ("sp", value_of_builtin_frame_sp_reg, NULL);
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user_reg_add_builtin ("ps", value_of_builtin_frame_ps_reg, NULL);
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}
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