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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>
89 lines
3.2 KiB
C++
89 lines
3.2 KiB
C++
/* Signal trampoline unwinder.
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Copyright (C) 2004-2024 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 TRAMP_FRAME_H
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#define TRAMP_FRAME_H
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#include "frame.h"
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#include "frame-unwind.h" /* For frame_prev_arch_ftype. */
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class frame_info_ptr;
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struct trad_frame_cache;
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/* A trampoline consists of a small sequence of instructions placed at
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an unspecified location in the inferior's address space. The only
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identifying attribute of the trampoline's address is that it does
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not fall inside an object file's section.
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The only way to identify a trampoline is to perform a brute force
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examination of the instructions at and around the PC.
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This module provides a convenient interface for performing that
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operation. */
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/* A trampoline descriptor. */
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/* Magic instruction that to mark the end of the signal trampoline
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instruction sequence. */
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#define TRAMP_SENTINEL_INSN ULONGEST_MAX
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struct tramp_frame
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{
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/* The trampoline's type, some a signal trampolines, some are normal
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call-frame trampolines (aka thunks). */
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enum frame_type frame_type;
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/* The trampoline's entire instruction sequence. It consists of a
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bytes/mask pair. Search for this in the inferior at or around
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the frame's PC. It is assumed that the PC is INSN_SIZE aligned,
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and that each element of TRAMP contains one INSN_SIZE
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instruction. It is also assumed that INSN[0] contains the first
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instruction of the trampoline and hence the address of the
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instruction matching INSN[0] is the trampoline's "func" address.
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The instruction sequence is terminated by
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TRAMP_SENTINEL_INSN. */
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int insn_size;
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struct
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{
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ULONGEST bytes;
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ULONGEST mask;
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} insn[48];
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/* Initialize a trad-frame cache corresponding to the tramp-frame.
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FUNC is the address of the instruction TRAMP[0] in memory. */
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void (*init) (const struct tramp_frame *self,
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const frame_info_ptr &this_frame,
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struct trad_frame_cache *this_cache,
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CORE_ADDR func);
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/* Return non-zero if the tramp-frame is valid for the PC requested.
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Adjust the PC to point to the address to check the instruction
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sequence against if required. If this is NULL, then the tramp-frame
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is valid for any PC. */
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int (*validate) (const struct tramp_frame *self,
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const frame_info_ptr &this_frame,
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CORE_ADDR *pc);
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/* Given the current frame in THIS_FRAME and a frame cache in FRAME_CACHE,
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return the architecture of the previous frame. */
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frame_prev_arch_ftype *prev_arch;
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};
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void tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,
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const struct tramp_frame *tramp);
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#endif
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