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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>
136 lines
4.0 KiB
C
136 lines
4.0 KiB
C
/* Target-dependent code for OpenBSD/alpha.
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Copyright (C) 2006-2024 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.h"
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#include "gdbcore.h"
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#include "osabi.h"
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#include "obsd-tdep.h"
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#include "alpha-tdep.h"
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#include "alpha-bsd-tdep.h"
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#include "solib-svr4.h"
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/* Signal trampolines. */
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/* The OpenBSD kernel maps the signal trampoline at some random
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location in user space, which means that the traditional BSD way of
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detecting it won't work.
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The signal trampoline will be mapped at an address that is page
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aligned. We recognize the signal trampoline by looking for the
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sigreturn system call. */
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static const int alphaobsd_page_size = 8192;
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static LONGEST
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alphaobsd_sigtramp_offset (struct gdbarch *gdbarch, CORE_ADDR pc)
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{
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return (pc & (alphaobsd_page_size - 1));
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}
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static int
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alphaobsd_pc_in_sigtramp (struct gdbarch *gdbarch,
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CORE_ADDR pc, const char *name)
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{
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CORE_ADDR start_pc = (pc & ~(alphaobsd_page_size - 1));
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unsigned insn;
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if (name)
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return 0;
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/* Check for "". */
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insn = alpha_read_insn (gdbarch, start_pc + 5 * ALPHA_INSN_SIZE);
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if (insn != 0x201f0067)
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return 0;
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/* Check for "". */
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insn = alpha_read_insn (gdbarch, start_pc + 6 * ALPHA_INSN_SIZE);
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if (insn != 0x00000083)
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return 0;
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return 1;
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}
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static CORE_ADDR
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alphaobsd_sigcontext_addr (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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CORE_ADDR pc = get_frame_pc (this_frame);
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if (alphaobsd_sigtramp_offset (gdbarch, pc) < 3 * ALPHA_INSN_SIZE)
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{
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/* On entry, a pointer the `struct sigcontext' is passed in %a2. */
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return get_frame_register_unsigned (this_frame, ALPHA_A0_REGNUM + 2);
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}
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else if (alphaobsd_sigtramp_offset (gdbarch, pc) < 4 * ALPHA_INSN_SIZE)
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{
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/* It is stored on the stack Before calling the signal handler. */
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CORE_ADDR sp;
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sp = get_frame_register_unsigned (this_frame, ALPHA_SP_REGNUM);
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return get_frame_memory_unsigned (this_frame, sp, 8);
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}
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else
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{
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/* It is reloaded into %a0 for the sigreturn(2) call. */
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return get_frame_register_unsigned (this_frame, ALPHA_A0_REGNUM);
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}
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}
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static void
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alphaobsd_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch)
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{
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alpha_gdbarch_tdep *tdep = gdbarch_tdep<alpha_gdbarch_tdep> (gdbarch);
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/* Hook into the DWARF CFI frame unwinder. */
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alpha_dwarf2_init_abi (info, gdbarch);
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/* Hook into the MDEBUG frame unwinder. */
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alpha_mdebug_init_abi (info, gdbarch);
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/* OpenBSD/alpha 3.0 and earlier does not provide single step
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support via ptrace(2); use software single-stepping for now. */
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set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
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/* OpenBSD/alpha has SVR4-style shared libraries. */
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set_solib_svr4_fetch_link_map_offsets
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(gdbarch, svr4_lp64_fetch_link_map_offsets);
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set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver);
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tdep->dynamic_sigtramp_offset = alphaobsd_sigtramp_offset;
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tdep->pc_in_sigtramp = alphaobsd_pc_in_sigtramp;
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tdep->sigcontext_addr = alphaobsd_sigcontext_addr;
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tdep->jb_pc = 2;
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tdep->jb_elt_size = 8;
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set_gdbarch_iterate_over_regset_sections
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(gdbarch, alphanbsd_iterate_over_regset_sections);
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}
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void _initialize_alphaobsd_tdep ();
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void
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_initialize_alphaobsd_tdep ()
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{
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gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD,
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alphaobsd_init_abi);
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}
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