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Tune string concatenation.

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This commit is contained in:
Mike Pall 2013-03-25 16:44:19 +01:00
parent 59329cfbbf
commit df94b81b2d
1 changed files with 22 additions and 36 deletions
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58
src/lj_meta.c
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@ -227,27 +227,14 @@ TValue *lj_meta_arith(lua_State *L, TValue *ra, cTValue *rb, cTValue *rc,
}
}
/* In-place coercion of a number to a string. */
static LJ_AINLINE int tostring(lua_State *L, TValue *o)
{
if (tvisstr(o)) {
return 1;
} else if (tvisnumber(o)) {
setstrV(L, o, lj_str_fromnumber(L, o));
return 1;
} else {
return 0;
}
}
/* Helper for CAT. Coercion, iterative concat, __concat metamethod. */
TValue *lj_meta_cat(lua_State *L, TValue *top, int left)
{
int fromc = 0;
if (left < 0) { left = -left; fromc = 1; }
do {
int n = 1;
if (!(tvisstr(top-1) || tvisnumber(top-1)) || !tostring(L, top)) {
if (!(tvisstr(top) || tvisnumber(top)) ||
!(tvisstr(top-1) || tvisnumber(top-1))) {
cTValue *mo = lj_meta_lookup(L, top-1, MM_concat);
if (tvisnil(mo)) {
mo = lj_meta_lookup(L, top, MM_concat);
@ -273,8 +260,6 @@ TValue *lj_meta_cat(lua_State *L, TValue *top, int left)
copyTV(L, top, mo);
setcont(top-1, lj_cont_cat);
return top+1; /* Trigger metamethod call. */
} else if (strV(top)->len == 0) { /* Shortcut. */
(void)tostring(L, top-1);
} else {
/* Pick as many strings as possible from the top and concatenate them:
**
@ -283,27 +268,28 @@ TValue *lj_meta_cat(lua_State *L, TValue *top, int left)
** concat: [...][CAT stack ...] [result]
** next step: [...][CAT stack ............]
*/
MSize tlen = strV(top)->len;
char *buf;
int i;
for (n = 1; n <= left && tostring(L, top-n); n++) {
MSize len = strV(top-n)->len;
if (len >= LJ_MAX_STR - tlen)
lj_err_msg(L, LJ_ERR_STROV);
tlen += len;
TValue *e, *o = top;
uint64_t tlen = tvisstr(o) ? strV(o)->len : LJ_STR_NUMBERBUF;
char *p, *buf;
do {
o--; tlen += tvisstr(o) ? strV(o)->len : LJ_STR_NUMBERBUF;
} while (--left > 0 && (tvisstr(o-1) || tvisnumber(o-1)));
if (tlen >= LJ_MAX_STR) lj_err_msg(L, LJ_ERR_STROV);
p = buf = lj_buf_tmp(L, (MSize)tlen);
for (e = top, top = o; o <= e; o++) {
if (tvisstr(o)) {
GCstr *s = strV(o);
MSize len = s->len;
p = lj_buf_wmem(p, strdata(s), len);
} else if (tvisint(o)) {
p = lj_str_bufint(p, intV(o));
} else {
lua_assert(tvisnum(o));
p = lj_str_bufnum(p, o);
}
}
buf = lj_buf_tmp(L, tlen);
n--;
tlen = 0;
for (i = n; i >= 0; i--) {
MSize len = strV(top-i)->len;
memcpy(buf + tlen, strVdata(top-i), len);
tlen += len;
}
setstrV(L, top-n, lj_str_new(L, buf, tlen));
setstrV(L, top, lj_str_new(L, buf, (size_t)(p-buf)));
}
left -= n;
top -= n;
} while (left >= 1);
if (LJ_UNLIKELY(G(L)->gc.total >= G(L)->gc.threshold)) {
if (!fromc) L->top = curr_topL(L);