Use set_table to track const caches

Now that we have a `set_table` implementation, we can
use it to track const caches and save some memory.

We could even save some more memory if `numtable` didn't
store a copy of the `hash` and instead recomputed it every
time, but this is a quick win.

common.mk

@@ -8903,6 +8903,7 @@ iseq.$(OBJEXT): $(top_srcdir)/internal/rational.h
 iseq.$(OBJEXT): $(top_srcdir)/internal/ruby_parser.h
 iseq.$(OBJEXT): $(top_srcdir)/internal/sanitizers.h
 iseq.$(OBJEXT): $(top_srcdir)/internal/serial.h
+iseq.$(OBJEXT): $(top_srcdir)/internal/set_table.h
 iseq.$(OBJEXT): $(top_srcdir)/internal/static_assert.h
 iseq.$(OBJEXT): $(top_srcdir)/internal/string.h
 iseq.$(OBJEXT): $(top_srcdir)/internal/symbol.h
@@ -19549,6 +19550,7 @@ vm.$(OBJEXT): $(top_srcdir)/internal/re.h
 vm.$(OBJEXT): $(top_srcdir)/internal/ruby_parser.h
 vm.$(OBJEXT): $(top_srcdir)/internal/sanitizers.h
 vm.$(OBJEXT): $(top_srcdir)/internal/serial.h
+vm.$(OBJEXT): $(top_srcdir)/internal/set_table.h
 vm.$(OBJEXT): $(top_srcdir)/internal/static_assert.h
 vm.$(OBJEXT): $(top_srcdir)/internal/string.h
 vm.$(OBJEXT): $(top_srcdir)/internal/struct.h

internal/set_table.h

@@ -35,6 +35,8 @@ typedef int set_update_callback_func(st_data_t *key, st_data_t arg, int existing
 size_t rb_set_table_size(const struct set_table *tbl);
 #define set_init_table_with_size rb_set_init_table_with_size
 set_table *rb_set_init_table_with_size(set_table *tab, const struct st_hash_type *, st_index_t);
+#define set_init_numtable rb_set_init_numtable
+set_table *rb_set_init_numtable(void);
 #define set_delete rb_set_delete
 int rb_set_delete(set_table *, st_data_t *); /* returns 0:notfound 1:deleted */
 #define set_insert rb_set_insert

iseq.c

@@ -31,6 +31,7 @@
 #include "internal/io.h"
 #include "internal/ruby_parser.h"
 #include "internal/sanitizers.h"
+#include "internal/set_table.h"
 #include "internal/symbol.h"
 #include "internal/thread.h"
 #include "internal/variable.h"
@@ -110,14 +111,14 @@ remove_from_constant_cache(ID id, IC ic)
     st_data_t ic_data = (st_data_t)ic;
 
     if (rb_id_table_lookup(vm->constant_cache, id, &lookup_result)) {
-        st_table *ics = (st_table *)lookup_result;
-        st_delete(ics, &ic_data, NULL);
+        set_table *ics = (set_table *)lookup_result;
+        set_delete(ics, &ic_data);
 
         if (ics->num_entries == 0 &&
                 // See comment in vm_track_constant_cache on why we need this check
                 id != vm->inserting_constant_cache_id) {
             rb_id_table_delete(vm->constant_cache, id);
-            st_free_table(ics);
+            set_free_table(ics);
         }
     }
 }

st.c

@@ -2459,6 +2459,12 @@ set_init_table_with_size(set_table *tab, const struct st_hash_type *type, st_ind
     return tab;
 }
 
+set_table *
+set_init_numtable(void)
+{
+    return set_init_table_with_size(NULL, &type_numhash, 0);
+}
+
 size_t
 set_table_size(const struct set_table *tbl)
 {

vm_insnhelper.c

@@ -26,6 +26,7 @@
 #include "internal/proc.h"
 #include "internal/random.h"
 #include "internal/variable.h"
+#include "internal/set_table.h"
 #include "internal/struct.h"
 #include "variable.h"
 
@@ -6332,13 +6333,13 @@ vm_track_constant_cache(ID id, void *ic)
     rb_vm_t *vm = GET_VM();
     struct rb_id_table *const_cache = vm->constant_cache;
     VALUE lookup_result;
-    st_table *ics;
+    set_table *ics;
 
     if (rb_id_table_lookup(const_cache, id, &lookup_result)) {
-        ics = (st_table *)lookup_result;
+        ics = (set_table *)lookup_result;
     }
     else {
-        ics = st_init_numtable();
+        ics = set_init_numtable();
         rb_id_table_insert(const_cache, id, (VALUE)ics);
     }
 
@@ -6356,7 +6357,7 @@ vm_track_constant_cache(ID id, void *ic)
      */
     vm->inserting_constant_cache_id = id;
 
-    st_insert(ics, (st_data_t) ic, (st_data_t) Qtrue);
+    set_insert(ics, (st_data_t)ic);
 
     vm->inserting_constant_cache_id = (ID)0;
 }

vm_method.c

@@ -125,7 +125,7 @@ vm_cme_invalidate(rb_callable_method_entry_t *cme)
 }
 
 static int
-rb_clear_constant_cache_for_id_i(st_data_t ic, st_data_t idx, st_data_t arg)
+rb_clear_constant_cache_for_id_i(st_data_t ic, st_data_t arg)
 {
     ((IC) ic)->entry = NULL;
     return ST_CONTINUE;
@@ -141,8 +141,8 @@ rb_clear_constant_cache_for_id(ID id)
     rb_vm_t *vm = GET_VM();
 
     if (rb_id_table_lookup(vm->constant_cache, id, &lookup_result)) {
-        st_table *ics = (st_table *)lookup_result;
-        st_foreach(ics, rb_clear_constant_cache_for_id_i, (st_data_t) NULL);
+        set_table *ics = (set_table *)lookup_result;
+        set_foreach(ics, rb_clear_constant_cache_for_id_i, (st_data_t) NULL);
         ruby_vm_constant_cache_invalidations += ics->num_entries;
     }