forked from Imagelibrary/binutils-gdb
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>
40 lines
1.3 KiB
C++
40 lines
1.3 KiB
C++
/* Definitions for virtual tail call frames unwinder for GDB.
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Copyright (C) 2010-2024 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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#ifndef DWARF2_FRAME_TAILCALL_H
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#define DWARF2_FRAME_TAILCALL_H 1
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class frame_info_ptr;
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struct frame_unwind;
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/* The tail call frame unwinder. */
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extern void
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dwarf2_tailcall_sniffer_first (const frame_info_ptr &this_frame,
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void **tailcall_cachep,
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const LONGEST *entry_cfa_sp_offsetp);
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extern struct value *
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dwarf2_tailcall_prev_register_first (const frame_info_ptr &this_frame,
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void **tailcall_cachep, int regnum);
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extern const struct frame_unwind dwarf2_tailcall_frame_unwind;
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#endif /* !DWARF2_FRAME_TAILCALL_H */
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