Removed internal cache for closures

The mechanism of "caching the last closure created for a prototype to
try to reuse it the next time a closure for that prototype is created"
was removed. There are several reasons:

- It is hard to find a natural example where this cache has a measurable
impact on performance.

- Programmers already perceive closure creation as something slow,
so they tend to avoid it inside hot paths. (Any case where the cache
could reuse a closure can be rewritten predefining the closure in some
variable and using that variable.)

- The implementation was somewhat complex, due to a bad interaction
with the generational collector. (Typically, new closures are new,
while prototypes are old. So, the cache breaks the invariant that
old objects should not point to new ones.)

1 files changed, 1 insertions, 1 deletions

diff --git a/lstate.c b/lstate.c
index 4a2453d1..9d399959 100644
--- a/lstate.c
+++ b/lstate.c
@@ -340,7 +340,7 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
   g->finobjsur = g->finobjold = g->finobjrold = NULL;
   g->sweepgc = NULL;
   g->gray = g->grayagain = NULL;
-  g->weak = g->ephemeron = g->allweak = g->protogray = NULL;
+  g->weak = g->ephemeron = g->allweak = NULL;
   g->twups = NULL;
   g->totalbytes = sizeof(LG);
   g->GCdebt = 0;