gdb: pass frames as `const frame_info_ptr &`

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>

1 files changed, 18 insertions, 18 deletions

diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index b9be394..80a04bf 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -1894,7 +1894,7 @@ gdbarch_pseudo_register_read_value_p (struct gdbarch *gdbarch)
 }
 
 struct value *
-gdbarch_pseudo_register_read_value (struct gdbarch *gdbarch, frame_info_ptr next_frame, int cookednum)
+gdbarch_pseudo_register_read_value (struct gdbarch *gdbarch, const frame_info_ptr &next_frame, int cookednum)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->pseudo_register_read_value != NULL);
@@ -1918,7 +1918,7 @@ gdbarch_pseudo_register_write_p (struct gdbarch *gdbarch)
 }
 
 void
-gdbarch_pseudo_register_write (struct gdbarch *gdbarch, frame_info_ptr next_frame, int pseudo_reg_num, gdb::array_view<const gdb_byte> buf)
+gdbarch_pseudo_register_write (struct gdbarch *gdbarch, const frame_info_ptr &next_frame, int pseudo_reg_num, gdb::array_view<const gdb_byte> buf)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->pseudo_register_write != NULL);
@@ -2240,7 +2240,7 @@ set_gdbarch_register_type (struct gdbarch *gdbarch,
 }
 
 struct frame_id
-gdbarch_dummy_id (struct gdbarch *gdbarch, frame_info_ptr this_frame)
+gdbarch_dummy_id (struct gdbarch *gdbarch, const frame_info_ptr &this_frame)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->dummy_id != NULL);
@@ -2339,7 +2339,7 @@ set_gdbarch_push_dummy_code (struct gdbarch *gdbarch,
 }
 
 int
-gdbarch_code_of_frame_writable (struct gdbarch *gdbarch, frame_info_ptr frame)
+gdbarch_code_of_frame_writable (struct gdbarch *gdbarch, const frame_info_ptr &frame)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->code_of_frame_writable != NULL);
@@ -2356,7 +2356,7 @@ set_gdbarch_code_of_frame_writable (struct gdbarch *gdbarch,
 }
 
 void
-gdbarch_print_registers_info (struct gdbarch *gdbarch, struct ui_file *file, frame_info_ptr frame, int regnum, int all)
+gdbarch_print_registers_info (struct gdbarch *gdbarch, struct ui_file *file, const frame_info_ptr &frame, int regnum, int all)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->print_registers_info != NULL);
@@ -2373,7 +2373,7 @@ set_gdbarch_print_registers_info (struct gdbarch *gdbarch,
 }
 
 void
-gdbarch_print_float_info (struct gdbarch *gdbarch, struct ui_file *file, frame_info_ptr frame, const char *args)
+gdbarch_print_float_info (struct gdbarch *gdbarch, struct ui_file *file, const frame_info_ptr &frame, const char *args)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->print_float_info != NULL);
@@ -2397,7 +2397,7 @@ gdbarch_print_vector_info_p (struct gdbarch *gdbarch)
 }
 
 void
-gdbarch_print_vector_info (struct gdbarch *gdbarch, struct ui_file *file, frame_info_ptr frame, const char *args)
+gdbarch_print_vector_info (struct gdbarch *gdbarch, struct ui_file *file, const frame_info_ptr &frame, const char *args)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->print_vector_info != NULL);
@@ -2472,7 +2472,7 @@ gdbarch_get_longjmp_target_p (struct gdbarch *gdbarch)
 }
 
 int
-gdbarch_get_longjmp_target (struct gdbarch *gdbarch, frame_info_ptr frame, CORE_ADDR *pc)
+gdbarch_get_longjmp_target (struct gdbarch *gdbarch, const frame_info_ptr &frame, CORE_ADDR *pc)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->get_longjmp_target != NULL);
@@ -2523,7 +2523,7 @@ set_gdbarch_convert_register_p (struct gdbarch *gdbarch,
 }
 
 int
-gdbarch_register_to_value (struct gdbarch *gdbarch, frame_info_ptr frame, int regnum, struct type *type, gdb_byte *buf, int *optimizedp, int *unavailablep)
+gdbarch_register_to_value (struct gdbarch *gdbarch, const frame_info_ptr &frame, int regnum, struct type *type, gdb_byte *buf, int *optimizedp, int *unavailablep)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->register_to_value != NULL);
@@ -2540,7 +2540,7 @@ set_gdbarch_register_to_value (struct gdbarch *gdbarch,
 }
 
 void
-gdbarch_value_to_register (struct gdbarch *gdbarch, frame_info_ptr frame, int regnum, struct type *type, const gdb_byte *buf)
+gdbarch_value_to_register (struct gdbarch *gdbarch, const frame_info_ptr &frame, int regnum, struct type *type, const gdb_byte *buf)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->value_to_register != NULL);
@@ -2656,7 +2656,7 @@ set_gdbarch_return_value_as_value (struct gdbarch *gdbarch,
 }
 
 CORE_ADDR
-gdbarch_get_return_buf_addr (struct gdbarch *gdbarch, struct type *val_type, frame_info_ptr cur_frame)
+gdbarch_get_return_buf_addr (struct gdbarch *gdbarch, struct type *val_type, const frame_info_ptr &cur_frame)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->get_return_buf_addr != NULL);
@@ -3048,7 +3048,7 @@ set_gdbarch_frame_args_skip (struct gdbarch *gdbarch,
 }
 
 CORE_ADDR
-gdbarch_unwind_pc (struct gdbarch *gdbarch, frame_info_ptr next_frame)
+gdbarch_unwind_pc (struct gdbarch *gdbarch, const frame_info_ptr &next_frame)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->unwind_pc != NULL);
@@ -3065,7 +3065,7 @@ set_gdbarch_unwind_pc (struct gdbarch *gdbarch,
 }
 
 CORE_ADDR
-gdbarch_unwind_sp (struct gdbarch *gdbarch, frame_info_ptr next_frame)
+gdbarch_unwind_sp (struct gdbarch *gdbarch, const frame_info_ptr &next_frame)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->unwind_sp != NULL);
@@ -3089,7 +3089,7 @@ gdbarch_frame_num_args_p (struct gdbarch *gdbarch)
 }
 
 int
-gdbarch_frame_num_args (struct gdbarch *gdbarch, frame_info_ptr frame)
+gdbarch_frame_num_args (struct gdbarch *gdbarch, const frame_info_ptr &frame)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->frame_num_args != NULL);
@@ -3348,7 +3348,7 @@ gdbarch_single_step_through_delay_p (struct gdbarch *gdbarch)
 }
 
 int
-gdbarch_single_step_through_delay (struct gdbarch *gdbarch, frame_info_ptr frame)
+gdbarch_single_step_through_delay (struct gdbarch *gdbarch, const frame_info_ptr &frame)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->single_step_through_delay != NULL);
@@ -3382,7 +3382,7 @@ set_gdbarch_print_insn (struct gdbarch *gdbarch,
 }
 
 CORE_ADDR
-gdbarch_skip_trampoline_code (struct gdbarch *gdbarch, frame_info_ptr frame, CORE_ADDR pc)
+gdbarch_skip_trampoline_code (struct gdbarch *gdbarch, const frame_info_ptr &frame, CORE_ADDR pc)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->skip_trampoline_code != NULL);
@@ -3723,7 +3723,7 @@ gdbarch_fetch_pointer_argument_p (struct gdbarch *gdbarch)
 }
 
 CORE_ADDR
-gdbarch_fetch_pointer_argument (struct gdbarch *gdbarch, frame_info_ptr frame, int argi, struct type *type)
+gdbarch_fetch_pointer_argument (struct gdbarch *gdbarch, const frame_info_ptr &frame, int argi, struct type *type)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->fetch_pointer_argument != NULL);
@@ -5414,7 +5414,7 @@ set_gdbarch_type_align (struct gdbarch *gdbarch,
 }
 
 std::string
-gdbarch_get_pc_address_flags (struct gdbarch *gdbarch, frame_info_ptr frame, CORE_ADDR pc)
+gdbarch_get_pc_address_flags (struct gdbarch *gdbarch, const frame_info_ptr &frame, CORE_ADDR pc)
 {
   gdb_assert (gdbarch != NULL);
   gdb_assert (gdbarch->get_pc_address_flags != NULL);