Put bytecode stack frame metadata in a struct

Using a plain C struct instead of type-punning Lisp_Object stack slots
makes the bytecode interpreter code more type-safe and potentially
faster (from better alias analysis), and the special-purpose accessors
are no longer needed.  It also reduces the stack requirements when
using 64-bit Lisp_Object on 32-bit platforms.

* src/bytecode.c (enum stack_frame_index)
(sf_get_ptr, sf_set_ptr, sf_get_lisp_ptr, sf_set_lisp_ptr,
sf_get_saved_pc, sf_set_saved_pc): Remove.
(BC_STACK_SIZE): Now in bytes, not Lisp words.
(struct bc_frame): New.
(init_bc_thread, mark_bytecode, Finternal_stack_stats, valid_sp)
(exec_byte_code):
* src/lisp.h (struct handler, get_act_rec, set_act_rec):
Adapt to new struct bc_frame.

1 files changed, 5 insertions, 3 deletions

diff --git a/src/thread.h b/src/thread.h
index a29af702d13..ddba1a2d994 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -35,9 +35,11 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 /* Byte-code interpreter thread state.  */
 struct bc_thread_state {
-  Lisp_Object *fp;              /* current frame pointer (see bytecode.c) */
-  Lisp_Object *stack;
-  Lisp_Object *stack_end;
+  struct bc_frame *fp;   /* current frame pointer */
+
+  /* start and end of allocated bytecode stack */
+  char *stack;
+  char *stack_end;
 };
 
 struct thread_state