struct: recycle conses used for slot lookups.

When a slot is not found in a cache, and in other situations
the object system conses up a key in order to search a the
global slot_hash. We should be recycling these keys
for reuse via rcyc_cons. This change makes recompilation of
TXR's library (make clean-tlo; make) about 1.6% faster.

* struct.c (lookup_slot, lookup_static_slot_desc, static_slot_p):
Recycle the hash key cons cell via rcyc_cons, so it can be
reused immediately.

1 files changed, 12 insertions, 0 deletions

diff --git a/struct.c b/struct.c
index 693c20dc..27853839 100644
--- a/struct.c
+++ b/struct.c
@@ -882,6 +882,9 @@ static loc lookup_slot(val inst, struct struct_inst *si, val sym)
       val key = cons(sym, num_fast(id));
       val sl = gethash(slot_hash, key);
       cnum slnum = coerce(cnum, sl) >> TAG_SHIFT;
+
+      rcyc_cons(key);
+
       if (sl) {
         cache_set_insert(*set, id, slnum);
         if (slnum >= STATIC_SLOT_BASE) {
@@ -904,6 +907,8 @@ static loc lookup_slot(val inst, struct struct_inst *si, val sym)
 
     sym->s.slot_cache = slot_cache;
 
+    rcyc_cons(key);
+
     if (sl) {
       cache_set_insert(*set, id, slnum);
       if (slnum >= STATIC_SLOT_BASE) {
@@ -934,6 +939,9 @@ static struct stslot *lookup_static_slot_desc(struct struct_type *st, val sym)
       val key = cons(sym, num_fast(id));
       val sl = gethash(slot_hash, key);
       cnum slnum = coerce(cnum, sl) >> TAG_SHIFT;
+
+      rcyc_cons(key);
+
       if (sl) {
         cache_set_insert(*set, id, slnum);
         if (slnum >= STATIC_SLOT_BASE)
@@ -951,6 +959,8 @@ static struct stslot *lookup_static_slot_desc(struct struct_type *st, val sym)
 
     sym->s.slot_cache = slot_cache;
 
+    rcyc_cons(key);
+
     if (sl) {
       cache_set_insert(*set, id, slnum);
       if (slnum >= STATIC_SLOT_BASE)
@@ -1318,6 +1328,8 @@ val static_slot_p(val type, val sym)
     val sl = gethash(slot_hash, key);
     cnum slnum = coerce(cnum, sl) >> TAG_SHIFT;
 
+    rcyc_cons(key);
+
     if (sl && slnum >= STATIC_SLOT_BASE)
       return t;
   }