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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>
118 lines
3.4 KiB
C
118 lines
3.4 KiB
C
/* Definitions for frame address handler, for GDB, the GNU debugger.
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Copyright (C) 2003-2024 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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#include "defs.h"
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#include "frame-base.h"
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#include "frame.h"
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#include "gdbsupport/gdb_obstack.h"
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#include "gdbarch.h"
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/* A default frame base implementations. If it wasn't for the old
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DEPRECATED_FRAME_LOCALS_ADDRESS and DEPRECATED_FRAME_ARGS_ADDRESS,
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these could be combined into a single function. All architectures
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really need to override this. */
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static CORE_ADDR
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default_frame_base_address (const frame_info_ptr &this_frame, void **this_cache)
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{
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return get_frame_base (this_frame); /* sigh! */
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}
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static CORE_ADDR
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default_frame_locals_address (const frame_info_ptr &this_frame, void **this_cache)
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{
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return default_frame_base_address (this_frame, this_cache);
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}
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static CORE_ADDR
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default_frame_args_address (const frame_info_ptr &this_frame, void **this_cache)
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{
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return default_frame_base_address (this_frame, this_cache);
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}
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const struct frame_base default_frame_base = {
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NULL, /* No parent. */
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default_frame_base_address,
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default_frame_locals_address,
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default_frame_args_address
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};
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struct frame_base_table_entry
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{
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frame_base_sniffer_ftype *sniffer;
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struct frame_base_table_entry *next;
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};
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struct frame_base_table
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{
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struct frame_base_table_entry *head = nullptr;
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struct frame_base_table_entry **tail = &head;
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const struct frame_base *default_base = &default_frame_base;
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};
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static const registry<gdbarch>::key<struct frame_base_table> frame_base_data;
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static struct frame_base_table *
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get_frame_base_table (struct gdbarch *gdbarch)
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{
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struct frame_base_table *table = frame_base_data.get (gdbarch);
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if (table == nullptr)
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table = frame_base_data.emplace (gdbarch);
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return table;
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}
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void
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frame_base_append_sniffer (struct gdbarch *gdbarch,
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frame_base_sniffer_ftype *sniffer)
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{
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struct frame_base_table *table = get_frame_base_table (gdbarch);
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(*table->tail)
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= GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_base_table_entry);
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(*table->tail)->sniffer = sniffer;
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table->tail = &(*table->tail)->next;
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}
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void
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frame_base_set_default (struct gdbarch *gdbarch,
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const struct frame_base *default_base)
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{
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struct frame_base_table *table = get_frame_base_table (gdbarch);
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table->default_base = default_base;
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}
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const struct frame_base *
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frame_base_find_by_frame (const frame_info_ptr &this_frame)
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{
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struct gdbarch *gdbarch = get_frame_arch (this_frame);
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struct frame_base_table *table = get_frame_base_table (gdbarch);
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struct frame_base_table_entry *entry;
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for (entry = table->head; entry != NULL; entry = entry->next)
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{
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const struct frame_base *desc = NULL;
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desc = entry->sniffer (this_frame);
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if (desc != NULL)
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return desc;
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}
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return table->default_base;
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}
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