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gdb: pass frames as const frame_info_ptr &

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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>
This commit is contained in:
Simon Marchi
2024-02-19 13:07:47 -05:00
parent 1b2c120daf
commit 8480a37e14
224 changed files with 1351 additions and 1339 deletions
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10
gdb/i386-linux-tdep.c
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@@ -122,7 +122,7 @@ static const gdb_byte linux_sigtramp_code[] =
start of the routine. Otherwise, return 0. */
static CORE_ADDR
i386_linux_sigtramp_start (frame_info_ptr this_frame)
i386_linux_sigtramp_start (const frame_info_ptr &this_frame)
{
CORE_ADDR pc = get_frame_pc (this_frame);
gdb_byte buf[LINUX_SIGTRAMP_LEN];
@@ -190,7 +190,7 @@ static const gdb_byte linux_rt_sigtramp_code[] =
start of the routine. Otherwise, return 0. */
static CORE_ADDR
i386_linux_rt_sigtramp_start (frame_info_ptr this_frame)
i386_linux_rt_sigtramp_start (const frame_info_ptr &this_frame)
{
CORE_ADDR pc = get_frame_pc (this_frame);
gdb_byte buf[LINUX_RT_SIGTRAMP_LEN];
@@ -227,7 +227,7 @@ i386_linux_rt_sigtramp_start (frame_info_ptr this_frame)
routine. */
static int
i386_linux_sigtramp_p (frame_info_ptr this_frame)
i386_linux_sigtramp_p (const frame_info_ptr &this_frame)
{
CORE_ADDR pc = get_frame_pc (this_frame);
const char *name;
@@ -252,7 +252,7 @@ i386_linux_sigtramp_p (frame_info_ptr this_frame)
static int
i386_linux_dwarf_signal_frame_p (struct gdbarch *gdbarch,
frame_info_ptr this_frame)
const frame_info_ptr &this_frame)
{
CORE_ADDR pc = get_frame_pc (this_frame);
const char *name;
@@ -275,7 +275,7 @@ i386_linux_dwarf_signal_frame_p (struct gdbarch *gdbarch,
address of the associated sigcontext structure. */
static CORE_ADDR
i386_linux_sigcontext_addr (frame_info_ptr this_frame)
i386_linux_sigcontext_addr (const frame_info_ptr &this_frame)
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);