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Optimize common 1-char case of string.sub/string.byte.

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Reported by Kacper Michajłow. #1497
This commit is contained in:
Mike Pall 2026-08-01 11:37:20 +02:00
parent afa81a5738
commit 594472579a
1 changed files with 11 additions and 0 deletions
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11
src/lj_ffrecord.c
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@ -846,6 +846,17 @@ static void LJ_FASTCALL recff_string_range(jit_State *J, RecordFFData *rd)
lj_ir_kint(J, 1));
end = end+(int32_t)str->len+1;
} else if ((MSize)end <= str->len) {
if (trstart == trend && start != 0) { /* Common 1-char case. */
TRef trptr, tr = emitir(IRTI(IR_ADD), trstart, lj_ir_kint(J, -1));
emitir(IRTGI(IR_ULT), tr, trlen);
trptr = emitir(IRT(IR_STRREF, IRT_PGC), trstr, tr);
if (rd->data) { /* Return string.sub result. */
J->base[0] = emitir(IRT(IR_SNEW, IRT_STR), trptr, lj_ir_kint(J, 1));
} else { /* Return string.byte result. */
J->base[0] = emitir(IRT(IR_XLOAD, IRT_U8), trptr, IRXLOAD_READONLY);
}
return;
}
emitir(IRTGI(IR_ULE), trend, trlen);
} else {
emitir(IRTGI(IR_GT), trend, trlen);