/* 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;
}
/* 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;
}
/* 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;
}
