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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>
73 lines
2.6 KiB
C++
73 lines
2.6 KiB
C++
/* Per-frame user registers, for GDB, the GNU debugger.
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Copyright (C) 2002-2024 Free Software Foundation, Inc.
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Contributed by Red Hat.
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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 USER_REGS_H
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#define USER_REGS_H
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/* Implement both builtin, and architecture specific, per-frame user
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visible registers.
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Builtin registers apply to all architectures, where as architecture
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specific registers are present when the architecture is selected.
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These registers are assigned register numbers outside the
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architecture's register range
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[0 .. gdbarch_num_regs + gdbarch_num_pseudo_regs].
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Their values should be constructed using per-frame information. */
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/* TODO: cagney/2003-06-27: Need to think more about how these
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registers are added, read, and modified. At present they are kind
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of assumed to be read-only. Should it, for instance, return a
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register descriptor that contains all the relevant access methods. */
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class frame_info_ptr;
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struct gdbarch;
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/* Given an architecture, map a user visible register name onto its
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index. */
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extern int user_reg_map_name_to_regnum (struct gdbarch *gdbarch,
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const char *str, int len);
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extern const char *user_reg_map_regnum_to_name (struct gdbarch *gdbarch,
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int regnum);
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/* Return the value of the frame register in the specified frame.
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Note; These methods return a "struct value" instead of the raw
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bytes as, at the time the register is being added, the type needed
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to describe the register has not bee initialized. */
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typedef struct value *(user_reg_read_ftype) (const frame_info_ptr &frame,
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const void *baton);
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extern struct value *value_of_user_reg (int regnum, const frame_info_ptr &frame);
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/* Add a builtin register (present in all architectures). */
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extern void user_reg_add_builtin (const char *name,
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user_reg_read_ftype *read,
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const void *baton);
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/* Add a per-architecture frame register. */
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extern void user_reg_add (struct gdbarch *gdbarch, const char *name,
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user_reg_read_ftype *read, const void *baton);
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#endif
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