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Redesign and harden string interning.

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Up to 40% faster on hash-intensive benchmarks.
With some ideas from Sokolov Yura.
This commit is contained in:
Mike Pall
2020-06-23 03:06:45 +02:00
parent a44f53acf5
commit ff34b48ddd
22 changed files with 394 additions and 202 deletions
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38
src/lj_gc.c
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@@ -417,6 +417,32 @@ static GCRef *gc_sweep(global_State *g, GCRef *p, uint32_t lim)
return p;
}
/* Sweep one string interning table chain. Preserves hashalg bit. */
static void gc_sweepstr(global_State *g, GCRef *chain)
{
/* Mask with other white and LJ_GC_FIXED. Or LJ_GC_SFIXED on shutdown. */
int ow = otherwhite(g);
uintptr_t u = gcrefu(*chain);
GCRef q;
GCRef *p = &q;
GCobj *o;
setgcrefp(q, (u & ~(uintptr_t)1));
while ((o = gcref(*p)) != NULL) {
if (((o->gch.marked ^ LJ_GC_WHITES) & ow)) { /* Black or current white? */
lj_assertG(!isdead(g, o) || (o->gch.marked & LJ_GC_FIXED),
"sweep of undead string");
makewhite(g, o); /* String is alive, change to the current white. */
p = &o->gch.nextgc;
} else { /* Otherwise string is dead, free it. */
lj_assertG(isdead(g, o) || ow == LJ_GC_SFIXED,
"sweep of unlive string");
setgcrefr(*p, o->gch.nextgc);
lj_str_free(g, gco2str(o));
}
}
setgcrefp(*chain, (gcrefu(q) | (u & 1)));
}
/* Check whether we can clear a key or a value slot from a table. */
static int gc_mayclear(cTValue *o, int val)
{
@@ -571,9 +597,9 @@ void lj_gc_freeall(global_State *g)
/* Free everything, except super-fixed objects (the main thread). */
g->gc.currentwhite = LJ_GC_WHITES | LJ_GC_SFIXED;
gc_fullsweep(g, &g->gc.root);
strmask = g->strmask;
strmask = g->str.mask;
for (i = 0; i <= strmask; i++) /* Free all string hash chains. */
gc_fullsweep(g, &g->strhash[i]);
gc_sweepstr(g, &g->str.tab[i]);
}
/* -- Collector ----------------------------------------------------------- */
@@ -636,8 +662,8 @@ static size_t gc_onestep(lua_State *L)
return 0;
case GCSsweepstring: {
GCSize old = g->gc.total;
gc_fullsweep(g, &g->strhash[g->gc.sweepstr++]); /* Sweep one chain. */
if (g->gc.sweepstr > g->strmask)
gc_sweepstr(g, &g->str.tab[g->gc.sweepstr++]); /* Sweep one chain. */
if (g->gc.sweepstr > g->str.mask)
g->gc.state = GCSsweep; /* All string hash chains sweeped. */
lj_assertG(old >= g->gc.total, "sweep increased memory");
g->gc.estimate -= old - g->gc.total;
@@ -649,8 +675,8 @@ static size_t gc_onestep(lua_State *L)
lj_assertG(old >= g->gc.total, "sweep increased memory");
g->gc.estimate -= old - g->gc.total;
if (gcref(*mref(g->gc.sweep, GCRef)) == NULL) {
if (g->strnum <= (g->strmask >> 2) && g->strmask > LJ_MIN_STRTAB*2-1)
lj_str_resize(L, g->strmask >> 1); /* Shrink string table. */
if (g->str.num <= (g->str.mask >> 2) && g->str.mask > LJ_MIN_STRTAB*2-1)
lj_str_resize(L, g->str.mask >> 1); /* Shrink string table. */
if (gcref(g->gc.mmudata)) { /* Need any finalizations? */
g->gc.state = GCSfinalize;
#if LJ_HASFFI