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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>
84 lines
3.2 KiB
C++
84 lines
3.2 KiB
C++
/* Code dealing with dummy stack frames, for GDB, the GNU debugger.
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Copyright (C) 2002-2024 Free Software Foundation, Inc.
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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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#if !defined (DUMMY_FRAME_H)
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#define DUMMY_FRAME_H 1
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#include "frame.h"
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struct infcall_suspend_state;
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struct frame_unwind;
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class thread_info;
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/* Push the information needed to identify, and unwind from, a dummy
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frame onto the dummy frame stack. */
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/* NOTE: cagney/2004-08-02: In the case of ABIs using push_dummy_code
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containing more than one instruction, this interface many need to
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be expanded so that it knowns the lower/upper extent of the dummy
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frame's code. */
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extern void dummy_frame_push (infcall_suspend_state *caller_state,
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const frame_id *dummy_id,
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thread_info *thread);
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/* Pop the dummy frame DUMMY_ID, restoring program state to that before the
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frame was created.
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On return reinit_frame_cache has been called.
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If the frame isn't found, flag an internal error.
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NOTE: This can only pop the one frame, even if it is in the middle of the
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stack, because the other frames may be for different threads, and there's
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currently no way to tell which stack frame is for which thread. */
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extern void dummy_frame_pop (frame_id dummy_id, thread_info *thread);
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extern void dummy_frame_discard (frame_id dummy_id, thread_info *thread);
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/* If the PC falls in a dummy frame, return a dummy frame
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unwinder. */
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extern const struct frame_unwind dummy_frame_unwind;
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/* Destructor for dummy_frame. DATA is supplied by registrant.
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REGISTERS_VALID is 1 for dummy_frame_pop, 0 for dummy_frame_discard. */
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typedef void (dummy_frame_dtor_ftype) (void *data, int registers_valid);
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/* Call DTOR with DTOR_DATA when DUMMY_ID frame of thread THREAD gets
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discarded. Dummy frame with DUMMY_ID must exist. Multiple
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destructors may be registered, they will be called in the reverse
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order of registrations (LIFO). */
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extern void register_dummy_frame_dtor (frame_id dummy_id,
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thread_info *thread,
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dummy_frame_dtor_ftype *dtor,
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void *dtor_data);
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/* Return 1 if there exists any dummy frame with any of its registered
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destructors equal to both DTOR and DTOR_DATA. Return 0 otherwise. */
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extern int find_dummy_frame_dtor (dummy_frame_dtor_ftype *dtor,
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void *dtor_data);
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/* Default implementation of gdbarch_dummy_id. Generate a dummy frame_id
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for THIS_FRAME assuming that the frame is a dummy frame. */
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extern struct frame_id default_dummy_id (struct gdbarch *gdbarch,
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const frame_info_ptr &this_frame);
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#endif /* !defined (DUMMY_FRAME_H) */
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