Improve gc-cons-percentage calculation

The old calculation relied on a hodgpodge of partly updated GC
stats to find a number to multiply gc-cons-percentage by.
The new one counts data found by the previous GC, plus half of
the data allocated since then; this is more systematic albeit
still ad hoc.
* src/alloc.c (consing_until_gc, gc_threshold, consing_threshold):
Now EMACS_INT, not intmax_t.
(HI_THRESHOLD): New macro.
(tally_consing): New function.
(make_interval, allocate_string, allocate_string_data)
(make_float, free_cons, allocate_vectorlike, Fmake_symbol): Use it.
(allow_garbage_collection, inhibit_garbage_collection)
(consing_threshold, garbage_collect):
Use HI_THRESHOLD rather than INTMAX_MAX.
(consing_threshold): New arg SINCE_GC.  All callers changed.
(bump_consing_until_gc): Return new consing_until_gc, instead of
nil.  All callers changed.  Don’t worry about overflow since we
now saturate at HI_THRESHOLD.  Guess that half of
recently-allocated objects are still alive, instead of relying on
the previous (even less-accurate) hodgepodge.
(maybe_garbage_collect): New function.
(garbage_collect): Work even if a finalizer disables or enables
memory profiling.  Do not use malloc_probe if GC reclaimed nothing.
* src/lisp.h (maybe_gc): Call maybe_garbage_collect instead
of garbage_collect.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 024e5edb26e..02f8a7b6686 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3824,9 +3824,10 @@ extern void mark_maybe_objects (Lisp_Object const *, ptrdiff_t);
 extern void mark_stack (char const *, char const *);
 extern void flush_stack_call_func (void (*func) (void *arg), void *arg);
 extern void garbage_collect (void);
+extern void maybe_garbage_collect (void);
 extern const char *pending_malloc_warning;
 extern Lisp_Object zero_vector;
-extern intmax_t consing_until_gc;
+extern EMACS_INT consing_until_gc;
 #ifdef HAVE_PDUMPER
 extern int number_finalizers_run;
 #endif
@@ -5056,7 +5057,7 @@ INLINE void
 maybe_gc (void)
 {
   if (consing_until_gc < 0)
-    garbage_collect ();
+    maybe_garbage_collect ();
 }
 
 INLINE_HEADER_END