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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/ada-lang.c
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@@ -11720,7 +11720,7 @@ ada_exception_support_info_sniffer (void)
to most users. */
static int
is_known_support_routine (frame_info_ptr frame)
is_known_support_routine (const frame_info_ptr &frame)
{
enum language func_lang;
int i;
@@ -11779,9 +11779,9 @@ is_known_support_routine (frame_info_ptr frame)
part of the Ada run-time, starting from FI and moving upward. */
void
ada_find_printable_frame (frame_info_ptr fi)
ada_find_printable_frame (const frame_info_ptr &initial_fi)
{
for (; fi != NULL; fi = get_prev_frame (fi))
for (frame_info_ptr fi = initial_fi; fi != nullptr; fi = get_prev_frame (fi))
{
if (!is_known_support_routine (fi))
{
@@ -12913,7 +12913,7 @@ ada_add_standard_exceptions (compiled_regex *preg,
static void
ada_add_exceptions_from_frame (compiled_regex *preg,
frame_info_ptr frame,
const frame_info_ptr &frame,
std::vector<ada_exc_info> *exceptions)
{
const struct block *block = get_frame_block (frame, 0);
@@ -13339,7 +13339,7 @@ public:
struct value *read_var_value (struct symbol *var,
const struct block *var_block,
frame_info_ptr frame) const override
const frame_info_ptr &frame) const override
{
/* The only case where default_read_var_value is not sufficient
is when VAR is a renaming... */