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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>
92 lines
3.2 KiB
C++
92 lines
3.2 KiB
C++
/* Definitions for a frame base, 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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#if !defined (FRAME_BASE_H)
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#define FRAME_BASE_H 1
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class frame_info_ptr;
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struct frame_id;
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struct frame_unwind;
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struct frame_base;
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struct gdbarch;
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struct regcache;
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/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
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and that this is a `normal frame'; use THIS frame, and implicitly
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the NEXT frame's register unwind method, to determine the address
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of THIS frame's `base'.
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The exact meaning of `base' is highly dependant on the type of the
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debug info. It is assumed that dwarf2, stabs, ... will each
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provide their own methods.
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A typical implementation will return the same value for base,
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locals-base and args-base. That value, however, will likely be
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different to the frame ID's stack address. */
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/* A generic base address. */
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typedef CORE_ADDR (frame_this_base_ftype) (const frame_info_ptr &this_frame,
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void **this_base_cache);
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/* The base address of the frame's local variables. */
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typedef CORE_ADDR (frame_this_locals_ftype) (const frame_info_ptr &this_frame,
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void **this_base_cache);
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/* The base address of the frame's arguments / parameters. */
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typedef CORE_ADDR (frame_this_args_ftype) (const frame_info_ptr &this_frame,
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void **this_base_cache);
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struct frame_base
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{
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/* If non-NULL, a low-level unwinder that shares its implementation
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with this high-level frame-base method. */
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const struct frame_unwind *unwind;
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frame_this_base_ftype *this_base;
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frame_this_locals_ftype *this_locals;
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frame_this_args_ftype *this_args;
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};
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/* Given THIS frame, return the frame base methods for THIS frame,
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or NULL if it can't handle THIS frame. */
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typedef const struct frame_base *(frame_base_sniffer_ftype) (const frame_info_ptr &this_frame);
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/* Append a frame base sniffer to the list. The sniffers are polled
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in the order that they are appended. */
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extern void frame_base_append_sniffer (struct gdbarch *gdbarch,
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frame_base_sniffer_ftype *sniffer);
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/* Set the default frame base. If all else fails, this one is
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returned. If this isn't set, the default is to use legacy code
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that uses things like the frame ID's base (ulgh!). */
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extern void frame_base_set_default (struct gdbarch *gdbarch,
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const struct frame_base *def);
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/* Iterate through the list of frame base handlers until one returns
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an implementation. */
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extern const struct frame_base *frame_base_find_by_frame (const frame_info_ptr &this_frame);
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#endif
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