DrSocalkwe3n/luajit
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No longer let the GC replace dead keys with the LJ_TDEADKEY tag.

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Important: this changes the semantics of the write barrier!
Carefully read the big comment block in lj_obj.h
This helps HREFK key slot specialization and allows safely hoisting
HREF/HREFK across GC steps, too (fix for a barely reproducible bug).
Dead keys are only removed during a table resize (as before).
This commit is contained in:
Mike Pall
2010-04-21 01:45:58 +02:00
parent d8cb69ed07
commit ab45481199
13 changed files with 65 additions and 43 deletions
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8
src/lj_gc.c
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@@ -186,13 +186,10 @@ static int gc_traverse_tab(global_State *g, GCtab *t)
MSize i, hmask = t->hmask;
for (i = 0; i <= hmask; i++) {
Node *n = &node[i];
lua_assert(itype(&n->key) != LJ_TDEADKEY || tvisnil(&n->val));
if (!tvisnil(&n->val)) { /* Mark non-empty slot. */
lua_assert(!tvisnil(&n->key));
if (!(weak & LJ_GC_WEAKKEY)) gc_marktv(g, &n->key);
if (!(weak & LJ_GC_WEAKVAL)) gc_marktv(g, &n->val);
} else if (tvisgcv(&n->key)) { /* Leave GC key in, but mark as dead. */
setitype(&n->key, LJ_TDEADKEY);
}
}
}
@@ -424,11 +421,8 @@ static void gc_clearweak(GCobj *o)
Node *n = &node[i];
/* Clear hash slot when key or value is about to be collected. */
if (!tvisnil(&n->val) && (gc_mayclear(&n->key, 0) ||
gc_mayclear(&n->val, 1))) {
gc_mayclear(&n->val, 1)))
setnilV(&n->val);
if (tvisgcv(&n->key)) /* Leave GC key in, but mark as dead. */
setitype(&n->key, LJ_TDEADKEY);
}
}
}
o = gcref(t->gclist);