static int recff_metacall(jit_State *J, RecordFFData *rd, MMS mm)
{
RecordIndex ix;
ix.tab = J->base[0];
copyTV(J->L, &ix.tabv, &rd->argv[0]);
if (lj_record_mm_lookup(J, &ix, mm)) { /* Has metamethod? */
int errcode;
TValue argv0;
/* Temporarily insert metamethod below object. */
J->base[1] = J->base[0];
J->base[0] = ix.mobj;
copyTV(J->L, &argv0, &rd->argv[0]);
copyTV(J->L, &rd->argv[1], &rd->argv[0]);
copyTV(J->L, &rd->argv[0], &ix.mobjv);
/* Need to protect lj_record_tailcall because it may throw. */
errcode = lj_vm_cpcall(J->L, NULL, J, recff_metacall_cp);
/* Always undo Lua stack changes to avoid confusing the interpreter. */
copyTV(J->L, &rd->argv[0], &argv0);
if (errcode)
lj_err_throw(J->L, errcode); /* Propagate errors. */
rd->nres = -1; /* Pending call. */
return 1; /* Tailcalled to metamethod. */
}
return 0;
}
/* Setup call to metamethod to be run by Assembler VM. */
static TValue *mmcall(lua_State *L, ASMFunction cont, cTValue *mo,
cTValue *a, cTValue *b)
{
/*
** |-- framesize -> top top+1 top+2 top+3
** before: [func slots ...]
** mm setup: [func slots ...] [cont|?] [mo|tmtype] [a] [b]
** in asm: [func slots ...] [cont|PC] [mo|delta] [a] [b]
** ^-- func base ^-- mm base
** after mm: [func slots ...] [result]
** ^-- copy to base[PC_RA] --/ for lj_cont_ra
** istruecond + branch for lj_cont_cond*
** ignore for lj_cont_nop
** next PC: [func slots ...]
*/
TValue *top = L->top;
if (curr_funcisL(L)) top = curr_topL(L);
setcont(top++, cont); /* Assembler VM stores PC in upper word or FR2. */
if (LJ_FR2) setnilV(top++);
copyTV(L, top++, mo); /* Store metamethod and two arguments. */
if (LJ_FR2) setnilV(top++);
copyTV(L, top, a);
copyTV(L, top+1, b);
return top; /* Return new base. */
}
/* Handle ctype __index/__newindex metamethods. */
static int ffi_index_meta(lua_State *L, CTState *cts, CType *ct, MMS mm)
{
CTypeID id = ctype_typeid(cts, ct);
cTValue *tv = lj_ctype_meta(cts, id, mm);
TValue *base = L->base;
if (!tv) {
const char *s;
err_index:
s = strdata(lj_ctype_repr(L, id, NULL));
if (tvisstr(L->base+1))
lj_err_callerv(L, LJ_ERR_FFI_BADMEMBER, s, strVdata(L->base+1));
else
lj_err_callerv(L, LJ_ERR_FFI_BADIDX, s);
}
if (!tvisfunc(tv)) {
if (mm == MM_index) {
cTValue *o = lj_meta_tget(L, tv, base+1);
if (o) {
if (tvisnil(o)) goto err_index;
copyTV(L, L->top-1, o);
return 1;
}
} else {
TValue *o = lj_meta_tset(L, tv, base+1);
if (o) {
copyTV(L, o, base+2);
return 0;
}
}
tv = L->top-1;
}
return lj_meta_tailcall(L, tv);
}
/* Helper for calls. __call metamethod. */
void lj_meta_call(lua_State *L, TValue *func, TValue *top)
{
cTValue *mo = lj_meta_lookup(L, func, MM_call);
TValue *p;
if (!tvisfunc(mo))
lj_err_optype_call(L, func);
for (p = top; p > func; p--) copyTV(L, p, p-1);
copyTV(L, func, mo);
}
static void LJ_FASTCALL recff_rawset(jit_State *J, RecordFFData *rd)
{
RecordIndex ix;
ix.tab = J->base[0]; ix.key = J->base[1]; ix.val = J->base[2];
if (tref_istab(ix.tab) && ix.key && ix.val) {
ix.idxchain = 0;
settabV(J->L, &ix.tabv, tabV(&rd->argv[0]));
copyTV(J->L, &ix.keyv, &rd->argv[1]);
copyTV(J->L, &ix.valv, &rd->argv[2]);
lj_record_idx(J, &ix);
/* Pass through table at J->base[0] as result. */
} /* else: Interpreter will throw. */
}
/* Tailcall from C function. */
int lj_meta_tailcall(lua_State *L, cTValue *tv)
{
TValue *base = L->base;
TValue *top = L->top;
const BCIns *pc = frame_pc(base-1); /* Preserve old PC from frame. */
copyTV(L, base-1-LJ_FR2, tv); /* Replace frame with new object. */
if (LJ_FR2)
(top++)->u64 = LJ_CONT_TAILCALL;
else
top->u32.lo = LJ_CONT_TAILCALL;
setframe_pc(top++, pc);
if (LJ_FR2) top++;
setframe_gc(top, obj2gco(L), LJ_TTHREAD); /* Dummy frame object. */
setframe_ftsz(top, ((char *)(top+1) - (char *)base) + FRAME_CONT);
L->base = L->top = top+1;
/*
** before: [old_mo|PC] [... ...]
** ^base ^top
** after: [new_mo|itype] [... ...] [NULL|PC] [dummy|delta]
** ^base/top
** tailcall: [new_mo|PC] [... ...]
** ^base ^top
*/
return 0;
}
LUALIB_API int luaL_loadfilex(lua_State *L, const char *filename,
const char *mode)
{
FileReaderCtx ctx;
int status;
const char *chunkname;
if (filename) {
ctx.fp = _lua_fopen(filename, "rb");
if (ctx.fp == NULL) {
lua_pushfstring(L, "cannot open %s: %s", filename, strerror(errno));
return LUA_ERRFILE;
}
chunkname = lua_pushfstring(L, "@%s", filename);
} else {
ctx.fp = stdin;
chunkname = "=stdin";
}
status = lua_loadx(L, reader_file, &ctx, chunkname, mode);
if (ferror(ctx.fp)) {
L->top -= filename ? 2 : 1;
lua_pushfstring(L, "cannot read %s: %s", chunkname+1, strerror(errno));
if (filename)
fclose(ctx.fp);
return LUA_ERRFILE;
}
if (filename) {
L->top--;
copyTV(L, L->top-1, L->top);
fclose(ctx.fp);
}
return status;
}
/* Unwind Lua stack and move error message to new top. */
LJ_NOINLINE static void unwindstack(lua_State *L, TValue *top)
{
lj_func_closeuv(L, top);
if (top < L->top-1) {
copyTV(L, top, L->top-1);
L->top = top+1;
}
lj_state_relimitstack(L);
}
/* Runtime error. */
LJ_NOINLINE void lj_err_run(lua_State *L)
{
ptrdiff_t ef = finderrfunc(L);
if (ef) {
TValue *errfunc = restorestack(L, ef);
TValue *top = L->top;
lj_trace_abort(G(L));
if (!tvisfunc(errfunc) || L->status == LUA_ERRERR) {
setstrV(L, top-1, lj_err_str(L, LJ_ERR_ERRERR));
lj_err_throw(L, LUA_ERRERR);
}
L->status = LUA_ERRERR;
copyTV(L, top, top-1);
copyTV(L, top-1, errfunc);
L->top = top+1;
lj_vm_call(L, top, 1+1); /* Stack: |errfunc|msg| -> |msg| */
}
lj_err_throw(L, LUA_ERRRUN);
}
static void LJ_FASTCALL recff_rawget(jit_State *J, RecordFFData *rd)
{
RecordIndex ix;
ix.tab = J->base[0]; ix.key = J->base[1];
if (tref_istab(ix.tab) && ix.key) {
ix.val = 0; ix.idxchain = 0;
settabV(J->L, &ix.tabv, tabV(&rd->argv[0]));
copyTV(J->L, &ix.keyv, &rd->argv[1]);
J->base[0] = lj_record_idx(J, &ix);
} /* else: Interpreter will throw. */
}
void cgAssertType(IRLS& env, const IRInstruction* inst) {
auto& v = vmain(env);
auto const& dtype = inst->dst()->type();
if (dtype == TBottom) {
v << ud2();
v = v.makeBlock();
return;
}
auto const dst = dstLoc(env, inst, 0);
auto const src = srcLoc(env, inst, 0);
copyTV(v, src, dst, dtype);
}
static void LJ_FASTCALL recff_getmetatable(jit_State *J, RecordFFData *rd)
{
TRef tr = J->base[0];
if (tr) {
RecordIndex ix;
ix.tab = tr;
copyTV(J->L, &ix.tabv, &rd->argv[0]);
if (lj_record_mm_lookup(J, &ix, MM_metatable))
J->base[0] = ix.mobj;
else
J->base[0] = ix.mt;
} /* else: Interpreter will throw. */
}
static int debug_getupvalue(lua_State *L, int get)
{
int32_t n = lj_lib_checkint(L, 2);
if (isluafunc(lj_lib_checkfunc(L, 1))) {
const char *name = get ? lua_getupvalue(L, 1, n) : lua_setupvalue(L, 1, n);
if (name) {
lua_pushstring(L, name);
if (!get) return 1;
copyTV(L, L->top, L->top-2);
L->top++;
return 2;
}
}
return 0;
}
static void LJ_FASTCALL recff_setmetatable(jit_State *J, RecordFFData *rd)
{
TRef tr = J->base[0];
TRef mt = J->base[1];
if (tref_istab(tr) && (tref_istab(mt) || (mt && tref_isnil(mt)))) {
TRef fref, mtref;
RecordIndex ix;
ix.tab = tr;
copyTV(J->L, &ix.tabv, &rd->argv[0]);
lj_record_mm_lookup(J, &ix, MM_metatable); /* Guard for no __metatable. */
fref = emitir(IRT(IR_FREF, IRT_P32), tr, IRFL_TAB_META);
mtref = tref_isnil(mt) ? lj_ir_knull(J, IRT_TAB) : mt;
emitir(IRT(IR_FSTORE, IRT_TAB), fref, mtref);
if (!tref_isnil(mt))
emitir(IRT(IR_TBAR, IRT_TAB), tr, 0);
J->base[0] = tr;
J->needsnap = 1;
} /* else: Interpreter will throw. */
}
/* Tailcall from C function. */
int lj_meta_tailcall(lua_State *L, cTValue *tv)
{
TValue *base = L->base;
TValue *top = L->top;
const BCIns *pc = frame_pc(base-1); /* Preserve old PC from frame. */
copyTV(L, base-1, tv); /* Replace frame with new object. */
top->u64 = 0;
setframe_pc(top, pc);
setframe_gc(top+1, obj2gco(L)); /* Dummy frame object. */
setframe_ftsz(top+1, (int)((char *)(top+2) - (char *)base) + FRAME_CONT);
L->base = L->top = top+2;
/*
** before: [old_mo|PC] [... ...]
** ^base ^top
** after: [new_mo|itype] [... ...] [NULL|PC] [dummy|delta]
** ^base/top
** tailcall: [new_mo|PC] [... ...]
** ^base ^top
*/
return 0;
}
/* Helper for equality comparisons. __eq metamethod. */
TValue *lj_meta_equal(lua_State *L, GCobj *o1, GCobj *o2, int ne)
{
/* Field metatable must be at same offset for GCtab and GCudata! */
cTValue *mo = lj_meta_fast(L, tabref(o1->gch.metatable), MM_eq);
if (mo) {
TValue *top;
uint32_t it;
if (tabref(o1->gch.metatable) != tabref(o2->gch.metatable)) {
cTValue *mo2 = lj_meta_fast(L, tabref(o2->gch.metatable), MM_eq);
if (mo2 == NULL || !lj_obj_equal(mo, mo2))
return (TValue *)(intptr_t)ne;
}
top = curr_top(L);
setcont(top, ne ? lj_cont_condf : lj_cont_condt);
copyTV(L, top+1, mo);
it = ~(uint32_t)o1->gch.gct;
setgcV(L, top+2, o1, it);
setgcV(L, top+3, o2, it);
return top+2; /* Trigger metamethod call. */
}
return (TValue *)(intptr_t)ne;
}
/* Helper for TSET*. __newindex chain and metamethod. */
TValue *lj_meta_tset(lua_State *L, cTValue *o, cTValue *k)
{
TValue tmp;
int loop;
for (loop = 0; loop < LJ_MAX_IDXCHAIN; loop++) {
cTValue *mo;
if (LJ_LIKELY(tvistab(o))) {
GCtab *t = tabV(o);
cTValue *tv = lj_tab_get(L, t, k);
if (LJ_LIKELY(!tvisnil(tv))) {
t->nomm = 0; /* Invalidate negative metamethod cache. */
lj_gc_anybarriert(L, t);
return (TValue *)tv;
} else if (!(mo = lj_meta_fast(L, tabref(t->metatable), MM_newindex))) {
t->nomm = 0; /* Invalidate negative metamethod cache. */
lj_gc_anybarriert(L, t);
if (tv != niltv(L))
return (TValue *)tv;
if (tvisnil(k)) lj_err_msg(L, LJ_ERR_NILIDX);
else if (tvisint(k)) { setnumV(&tmp, (lua_Number)intV(k)); k = &tmp; }
else if (tvisnum(k) && tvisnan(k)) lj_err_msg(L, LJ_ERR_NANIDX);
return lj_tab_newkey(L, t, k);
}
} else if (tvisnil(mo = lj_meta_lookup(L, o, MM_newindex))) {
lj_err_optype(L, o, LJ_ERR_OPINDEX);
return NULL; /* unreachable */
}
if (tvisfunc(mo)) {
L->top = mmcall(L, lj_cont_nop, mo, o, k);
/* L->top+2 = v filled in by caller. */
return NULL; /* Trigger metamethod call. */
}
copyTV(L, &tmp, mo);
o = &tmp;
}
lj_err_msg(L, LJ_ERR_SETLOOP);
return NULL; /* unreachable */
}
static void LJ_FASTCALL recff_xpcall(jit_State *J, RecordFFData *rd)
{
if (J->maxslot >= 2) {
TValue argv0, argv1;
TRef tmp;
int errcode;
/* Swap function and traceback. */
tmp = J->base[0]; J->base[0] = J->base[1]; J->base[1] = tmp;
copyTV(J->L, &argv0, &rd->argv[0]);
copyTV(J->L, &argv1, &rd->argv[1]);
copyTV(J->L, &rd->argv[0], &argv1);
copyTV(J->L, &rd->argv[1], &argv0);
/* Need to protect lj_record_call because it may throw. */
errcode = lj_vm_cpcall(J->L, NULL, J, recff_xpcall_cp);
/* Always undo Lua stack swap to avoid confusing the interpreter. */
copyTV(J->L, &rd->argv[0], &argv0);
copyTV(J->L, &rd->argv[1], &argv1);
if (errcode)
lj_err_throw(J->L, errcode); /* Propagate errors. */
rd->nres = -1; /* Pending call. */
} /* else: Interpreter will throw. */
}
/* Restore interpreter state from exit state with the help of a snapshot. */
const BCIns *lj_snap_restore(jit_State *J, void *exptr)
{
ExitState *ex = (ExitState *)exptr;
SnapNo snapno = J->exitno; /* For now, snapno == exitno. */
GCtrace *T = traceref(J, J->parent);
SnapShot *snap = &T->snap[snapno];
MSize n, nent = snap->nent;
SnapEntry *map = &T->snapmap[snap->mapofs];
SnapEntry *flinks = &T->snapmap[snap_nextofs(T, snap)-1];
ptrdiff_t ftsz0;
TValue *frame;
BloomFilter rfilt = snap_renamefilter(T, snapno);
const BCIns *pc = snap_pc(map[nent]);
lua_State *L = J->L;
/* Set interpreter PC to the next PC to get correct error messages. */
setcframe_pc(cframe_raw(L->cframe), pc+1);
/* Make sure the stack is big enough for the slots from the snapshot. */
if (LJ_UNLIKELY(L->base + snap->topslot >= tvref(L->maxstack))) {
L->top = curr_topL(L);
lj_state_growstack(L, snap->topslot - curr_proto(L)->framesize);
}
/* Fill stack slots with data from the registers and spill slots. */
frame = L->base-1;
ftsz0 = frame_ftsz(frame); /* Preserve link to previous frame in slot #0. */
for (n = 0; n < nent; n++) {
SnapEntry sn = map[n];
if (!(sn & SNAP_NORESTORE)) {
TValue *o = &frame[snap_slot(sn)];
IRRef ref = snap_ref(sn);
IRIns *ir = &T->ir[ref];
if (ir->r == RID_SUNK) {
MSize j;
for (j = 0; j < n; j++)
if (snap_ref(map[j]) == ref) { /* De-duplicate sunk allocations. */
copyTV(L, o, &frame[snap_slot(map[j])]);
goto dupslot;
}
snap_unsink(J, T, ex, snapno, rfilt, ir, o);
dupslot:
continue;
}
snap_restoreval(J, T, ex, snapno, rfilt, ref, o);
if (LJ_SOFTFP && (sn & SNAP_SOFTFPNUM) && tvisint(o)) {
TValue tmp;
snap_restoreval(J, T, ex, snapno, rfilt, ref+1, &tmp);
o->u32.hi = tmp.u32.lo;
} else if ((sn & (SNAP_CONT|SNAP_FRAME))) {
lua_assert(!LJ_FR2); /* TODO_FR2: store 64 bit PCs. */
/* Overwrite tag with frame link. */
setframe_ftsz(o, snap_slot(sn) != 0 ? (int32_t)*flinks-- : ftsz0);
L->base = o+1;
}
}
}
lua_assert(map + nent == flinks);
/* Compute current stack top. */
switch (bc_op(*pc)) {
default:
if (bc_op(*pc) < BC_FUNCF) {
L->top = curr_topL(L);
break;
}
/* fallthrough */
case BC_CALLM: case BC_CALLMT: case BC_RETM: case BC_TSETM:
L->top = frame + snap->nslots;
break;
}
return pc;
}
/* 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 {
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);
if (tvisnil(mo)) {
if (tvisstr(top-1) || tvisnumber(top-1)) top++;
lj_err_optype(L, top-1, LJ_ERR_OPCAT);
return NULL; /* unreachable */
}
}
/* One of the top two elements is not a string, call __cat metamethod:
**
** before: [...][CAT stack .........................]
** top-1 top top+1 top+2
** pick two: [...][CAT stack ...] [o1] [o2]
** setup mm: [...][CAT stack ...] [cont|?] [mo|tmtype] [o1] [o2]
** in asm: [...][CAT stack ...] [cont|PC] [mo|delta] [o1] [o2]
** ^-- func base ^-- mm base
** after mm: [...][CAT stack ...] <--push-- [result]
** next step: [...][CAT stack .............]
*/
copyTV(L, top+2*LJ_FR2+2, top); /* Carefully ordered stack copies! */
copyTV(L, top+2*LJ_FR2+1, top-1);
copyTV(L, top+LJ_FR2, mo);
setcont(top-1, lj_cont_cat);
if (LJ_FR2) { setnilV(top); setnilV(top+2); top += 2; }
return top+1; /* Trigger metamethod call. */
} else {
/* Pick as many strings as possible from the top and concatenate them:
**
** before: [...][CAT stack ...........................]
** pick str: [...][CAT stack ...] [...... strings ......]
** concat: [...][CAT stack ...] [result]
** next step: [...][CAT stack ............]
*/
TValue *e, *o = top;
uint64_t tlen = tvisstr(o) ? strV(o)->len : STRFMT_MAXBUF_NUM;
char *p, *buf;
do {
o--; tlen += tvisstr(o) ? strV(o)->len : STRFMT_MAXBUF_NUM;
} 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_strfmt_wint(p, intV(o));
} else {
lua_assert(tvisnum(o));
p = lj_strfmt_wnum(p, o);
}
}
setstrV(L, top, lj_str_new(L, buf, (size_t)(p-buf)));
}
} while (left >= 1);
if (LJ_UNLIKELY(G(L)->gc.total >= G(L)->gc.threshold)) {
if (!fromc) L->top = curr_topL(L);
lj_gc_step(L);
}
return NULL;
}
void lj_lib_register(lua_State *L, const char *libname,
const uint8_t *p, const lua_CFunction *cf)
{
GCtab *env = tabref(L->env);
GCfunc *ofn = NULL;
int ffid = *p++;
BCIns *bcff = &L2GG(L)->bcff[*p++];
GCtab *tab = lib_create_table(L, libname, *p++);
ptrdiff_t tpos = L->top - L->base;
/* Avoid barriers further down. */
lj_gc_anybarriert(L, tab);
tab->nomm = 0;
for (;;) {
uint32_t tag = *p++;
MSize len = tag & LIBINIT_LENMASK;
tag &= LIBINIT_TAGMASK;
if (tag != LIBINIT_STRING) {
const char *name;
MSize nuv = (MSize)(L->top - L->base - tpos);
GCfunc *fn = lj_func_newC(L, nuv, env);
if (nuv) {
L->top = L->base + tpos;
memcpy(fn->c.upvalue, L->top, sizeof(TValue)*nuv);
}
fn->c.ffid = (uint8_t)(ffid++);
name = (const char *)p;
p += len;
if (tag == LIBINIT_CF)
setmref(fn->c.pc, &G(L)->bc_cfunc_int);
else
setmref(fn->c.pc, bcff++);
if (tag == LIBINIT_ASM_)
fn->c.f = ofn->c.f; /* Copy handler from previous function. */
else
fn->c.f = *cf++; /* Get cf or handler from C function table. */
if (len) {
/* NOBARRIER: See above for common barrier. */
setfuncV(L, lj_tab_setstr(L, tab, lj_str_new(L, name, len)), fn);
}
ofn = fn;
} else {
switch (tag | len) {
case LIBINIT_SET:
L->top -= 2;
if (tvisstr(L->top+1) && strV(L->top+1)->len == 0)
env = tabV(L->top);
else /* NOBARRIER: See above for common barrier. */
copyTV(L, lj_tab_set(L, tab, L->top+1), L->top);
break;
case LIBINIT_NUMBER:
memcpy(&L->top->n, p, sizeof(double));
L->top++;
p += sizeof(double);
break;
case LIBINIT_COPY:
copyTV(L, L->top, L->top - *p++);
L->top++;
break;
case LIBINIT_LASTCL:
setfuncV(L, L->top++, ofn);
break;
case LIBINIT_FFID:
ffid++;
break;
case LIBINIT_END:
return;
default:
setstrV(L, L->top++, lj_str_new(L, (const char *)p, len));
p += len;
break;
}
}
}
}
/* Helper for CAT. Coercion, iterative concat, __concat metamethod. */
TValue *lj_meta_cat(lua_State *L, TValue *top, int left)
{
do {
int n = 1;
if (!(tvisstr(top-1) || tvisnumber(top-1)) || !tostring(L, top)) {
cTValue *mo = lj_meta_lookup(L, top-1, MM_concat);
if (tvisnil(mo)) {
mo = lj_meta_lookup(L, top, MM_concat);
if (tvisnil(mo)) {
if (tvisstr(top-1) || tvisnumber(top-1)) top++;
lj_err_optype(L, top-1, LJ_ERR_OPCAT);
return NULL; /* unreachable */
}
}
/* One of the top two elements is not a string, call __cat metamethod:
**
** before: [...][CAT stack .........................]
** top-1 top top+1 top+2
** pick two: [...][CAT stack ...] [o1] [o2]
** setup mm: [...][CAT stack ...] [cont|?] [mo|tmtype] [o1] [o2]
** in asm: [...][CAT stack ...] [cont|PC] [mo|delta] [o1] [o2]
** ^-- func base ^-- mm base
** after mm: [...][CAT stack ...] <--push-- [result]
** next step: [...][CAT stack .............]
*/
copyTV(L, top+2, top); /* Careful with the order of stack copies! */
copyTV(L, top+1, top-1);
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:
**
** before: [...][CAT stack ...........................]
** pick str: [...][CAT stack ...] [...... strings ......]
** concat: [...][CAT stack ...] [result]
** next step: [...][CAT stack ............]
*/
MSize tlen = strV(top)->len;
char *buffer;
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;
}
buffer = lj_str_needbuf(L, &G(L)->tmpbuf, tlen);
n--;
tlen = 0;
for (i = n; i >= 0; i--) {
MSize len = strV(top-i)->len;
memcpy(buffer + tlen, strVdata(top-i), len);
tlen += len;
}
setstrV(L, top-n, lj_str_new(L, buffer, tlen));
}
left -= n;
top -= n;
} while (left >= 1);
lj_gc_check_fixtop(L);
return NULL;
}
