1 files changed, 699 insertions, 0 deletions

diff --git a/src/lua-5.3/ldebug.c b/src/lua-5.3/ldebug.c
new file mode 100644
index 0000000..e138929
--- /dev/null
+++ b/src/lua-5.3/ldebug.c
@@ -0,0 +1,699 @@
+/*
+** $Id: ldebug.c,v 2.121.1.2 2017/07/10 17:21:50 roberto Exp $
+** Debug Interface
+** See Copyright Notice in lua.h
+*/
+
+#define ldebug_c
+#define LUA_CORE
+
+#include "lprefix.h"
+
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <string.h>
+
+#include "lua.h"
+
+#include "lapi.h"
+#include "lcode.h"
+#include "ldebug.h"
+#include "ldo.h"
+#include "lfunc.h"
+#include "lobject.h"
+#include "lopcodes.h"
+#include "lstate.h"
+#include "lstring.h"
+#include "ltable.h"
+#include "ltm.h"
+#include "lvm.h"
+
+
+
+#define noLuaClosure(f)         ((f) == NULL || (f)->c.tt == LUA_TCCL)
+
+
+/* Active Lua function (given call info) */
+#define ci_func(ci)             (clLvalue((ci)->func))
+
+
+static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
+                                    const char **name);
+
+
+static int currentpc (CallInfo *ci) {
+  lua_assert(isLua(ci));
+  return pcRel(ci->u.l.savedpc, ci_func(ci)->p);
+}
+
+
+static int currentline (CallInfo *ci) {
+  return getfuncline(ci_func(ci)->p, currentpc(ci));
+}
+
+
+/*
+** If function yielded, its 'func' can be in the 'extra' field. The
+** next function restores 'func' to its correct value for debugging
+** purposes. (It exchanges 'func' and 'extra'; so, when called again,
+** after debugging, it also "re-restores" ** 'func' to its altered value.
+*/
+static void swapextra (lua_State *L) {
+  if (L->status == LUA_YIELD) {
+    CallInfo *ci = L->ci;  /* get function that yielded */
+    StkId temp = ci->func;  /* exchange its 'func' and 'extra' values */
+    ci->func = restorestack(L, ci->extra);
+    ci->extra = savestack(L, temp);
+  }
+}
+
+
+/*
+** This function can be called asynchronously (e.g. during a signal).
+** Fields 'oldpc', 'basehookcount', and 'hookcount' (set by
+** 'resethookcount') are for debug only, and it is no problem if they
+** get arbitrary values (causes at most one wrong hook call). 'hookmask'
+** is an atomic value. We assume that pointers are atomic too (e.g., gcc
+** ensures that for all platforms where it runs). Moreover, 'hook' is
+** always checked before being called (see 'luaD_hook').
+*/
+LUA_API void lua_sethook (lua_State *L, lua_Hook func, int mask, int count) {
+  if (func == NULL || mask == 0) {  /* turn off hooks? */
+    mask = 0;
+    func = NULL;
+  }
+  if (isLua(L->ci))
+    L->oldpc = L->ci->u.l.savedpc;
+  L->hook = func;
+  L->basehookcount = count;
+  resethookcount(L);
+  L->hookmask = cast_byte(mask);
+}
+
+
+LUA_API lua_Hook lua_gethook (lua_State *L) {
+  return L->hook;
+}
+
+
+LUA_API int lua_gethookmask (lua_State *L) {
+  return L->hookmask;
+}
+
+
+LUA_API int lua_gethookcount (lua_State *L) {
+  return L->basehookcount;
+}
+
+
+LUA_API int lua_getstack (lua_State *L, int level, lua_Debug *ar) {
+  int status;
+  CallInfo *ci;
+  if (level < 0) return 0;  /* invalid (negative) level */
+  lua_lock(L);
+  for (ci = L->ci; level > 0 && ci != &L->base_ci; ci = ci->previous)
+    level--;
+  if (level == 0 && ci != &L->base_ci) {  /* level found? */
+    status = 1;
+    ar->i_ci = ci;
+  }
+  else status = 0;  /* no such level */
+  lua_unlock(L);
+  return status;
+}
+
+
+static const char *upvalname (Proto *p, int uv) {
+  TString *s = check_exp(uv < p->sizeupvalues, p->upvalues[uv].name);
+  if (s == NULL) return "?";
+  else return getstr(s);
+}
+
+
+static const char *findvararg (CallInfo *ci, int n, StkId *pos) {
+  int nparams = clLvalue(ci->func)->p->numparams;
+  if (n >= cast_int(ci->u.l.base - ci->func) - nparams)
+    return NULL;  /* no such vararg */
+  else {
+    *pos = ci->func + nparams + n;
+    return "(*vararg)";  /* generic name for any vararg */
+  }
+}
+
+
+static const char *findlocal (lua_State *L, CallInfo *ci, int n,
+                              StkId *pos) {
+  const char *name = NULL;
+  StkId base;
+  if (isLua(ci)) {
+    if (n < 0)  /* access to vararg values? */
+      return findvararg(ci, -n, pos);
+    else {
+      base = ci->u.l.base;
+      name = luaF_getlocalname(ci_func(ci)->p, n, currentpc(ci));
+    }
+  }
+  else
+    base = ci->func + 1;
+  if (name == NULL) {  /* no 'standard' name? */
+    StkId limit = (ci == L->ci) ? L->top : ci->next->func;
+    if (limit - base >= n && n > 0)  /* is 'n' inside 'ci' stack? */
+      name = "(*temporary)";  /* generic name for any valid slot */
+    else
+      return NULL;  /* no name */
+  }
+  *pos = base + (n - 1);
+  return name;
+}
+
+
+LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
+  const char *name;
+  lua_lock(L);
+  swapextra(L);
+  if (ar == NULL) {  /* information about non-active function? */
+    if (!isLfunction(L->top - 1))  /* not a Lua function? */
+      name = NULL;
+    else  /* consider live variables at function start (parameters) */
+      name = luaF_getlocalname(clLvalue(L->top - 1)->p, n, 0);
+  }
+  else {  /* active function; get information through 'ar' */
+    StkId pos = NULL;  /* to avoid warnings */
+    name = findlocal(L, ar->i_ci, n, &pos);
+    if (name) {
+      setobj2s(L, L->top, pos);
+      api_incr_top(L);
+    }
+  }
+  swapextra(L);
+  lua_unlock(L);
+  return name;
+}
+
+
+LUA_API const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n) {
+  StkId pos = NULL;  /* to avoid warnings */
+  const char *name;
+  lua_lock(L);
+  swapextra(L);
+  name = findlocal(L, ar->i_ci, n, &pos);
+  if (name) {
+    setobjs2s(L, pos, L->top - 1);
+    L->top--;  /* pop value */
+  }
+  swapextra(L);
+  lua_unlock(L);
+  return name;
+}
+
+
+static void funcinfo (lua_Debug *ar, Closure *cl) {
+  if (noLuaClosure(cl)) {
+    ar->source = "=[C]";
+    ar->linedefined = -1;
+    ar->lastlinedefined = -1;
+    ar->what = "C";
+  }
+  else {
+    Proto *p = cl->l.p;
+    ar->source = p->source ? getstr(p->source) : "=?";
+    ar->linedefined = p->linedefined;
+    ar->lastlinedefined = p->lastlinedefined;
+    ar->what = (ar->linedefined == 0) ? "main" : "Lua";
+  }
+  luaO_chunkid(ar->short_src, ar->source, LUA_IDSIZE);
+}
+
+
+static void collectvalidlines (lua_State *L, Closure *f) {
+  if (noLuaClosure(f)) {
+    setnilvalue(L->top);
+    api_incr_top(L);
+  }
+  else {
+    int i;
+    TValue v;
+    int *lineinfo = f->l.p->lineinfo;
+    Table *t = luaH_new(L);  /* new table to store active lines */
+    sethvalue(L, L->top, t);  /* push it on stack */
+    api_incr_top(L);
+    setbvalue(&v, 1);  /* boolean 'true' to be the value of all indices */
+    for (i = 0; i < f->l.p->sizelineinfo; i++)  /* for all lines with code */
+      luaH_setint(L, t, lineinfo[i], &v);  /* table[line] = true */
+  }
+}
+
+
+static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
+  if (ci == NULL)  /* no 'ci'? */
+    return NULL;  /* no info */
+  else if (ci->callstatus & CIST_FIN) {  /* is this a finalizer? */
+    *name = "__gc";
+    return "metamethod";  /* report it as such */
+  }
+  /* calling function is a known Lua function? */
+  else if (!(ci->callstatus & CIST_TAIL) && isLua(ci->previous))
+    return funcnamefromcode(L, ci->previous, name);
+  else return NULL;  /* no way to find a name */
+}
+
+
+static int auxgetinfo (lua_State *L, const char *what, lua_Debug *ar,
+                       Closure *f, CallInfo *ci) {
+  int status = 1;
+  for (; *what; what++) {
+    switch (*what) {
+      case 'S': {
+        funcinfo(ar, f);
+        break;
+      }
+      case 'l': {
+        ar->currentline = (ci && isLua(ci)) ? currentline(ci) : -1;
+        break;
+      }
+      case 'u': {
+        ar->nups = (f == NULL) ? 0 : f->c.nupvalues;
+        if (noLuaClosure(f)) {
+          ar->isvararg = 1;
+          ar->nparams = 0;
+        }
+        else {
+          ar->isvararg = f->l.p->is_vararg;
+          ar->nparams = f->l.p->numparams;
+        }
+        break;
+      }
+      case 't': {
+        ar->istailcall = (ci) ? ci->callstatus & CIST_TAIL : 0;
+        break;
+      }
+      case 'n': {
+        ar->namewhat = getfuncname(L, ci, &ar->name);
+        if (ar->namewhat == NULL) {
+          ar->namewhat = "";  /* not found */
+          ar->name = NULL;
+        }
+        break;
+      }
+      case 'L':
+      case 'f':  /* handled by lua_getinfo */
+        break;
+      default: status = 0;  /* invalid option */
+    }
+  }
+  return status;
+}
+
+
+LUA_API int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar) {
+  int status;
+  Closure *cl;
+  CallInfo *ci;
+  StkId func;
+  lua_lock(L);
+  swapextra(L);
+  if (*what == '>') {
+    ci = NULL;
+    func = L->top - 1;
+    api_check(L, ttisfunction(func), "function expected");
+    what++;  /* skip the '>' */
+    L->top--;  /* pop function */
+  }
+  else {
+    ci = ar->i_ci;
+    func = ci->func;
+    lua_assert(ttisfunction(ci->func));
+  }
+  cl = ttisclosure(func) ? clvalue(func) : NULL;
+  status = auxgetinfo(L, what, ar, cl, ci);
+  if (strchr(what, 'f')) {
+    setobjs2s(L, L->top, func);
+    api_incr_top(L);
+  }
+  swapextra(L);  /* correct before option 'L', which can raise a mem. error */
+  if (strchr(what, 'L'))
+    collectvalidlines(L, cl);
+  lua_unlock(L);
+  return status;
+}
+
+
+/*
+** {======================================================
+** Symbolic Execution
+** =======================================================
+*/
+
+static const char *getobjname (Proto *p, int lastpc, int reg,
+                               const char **name);
+
+
+/*
+** find a "name" for the RK value 'c'
+*/
+static void kname (Proto *p, int pc, int c, const char **name) {
+  if (ISK(c)) {  /* is 'c' a constant? */
+    TValue *kvalue = &p->k[INDEXK(c)];
+    if (ttisstring(kvalue)) {  /* literal constant? */
+      *name = svalue(kvalue);  /* it is its own name */
+      return;
+    }
+    /* else no reasonable name found */
+  }
+  else {  /* 'c' is a register */
+    const char *what = getobjname(p, pc, c, name); /* search for 'c' */
+    if (what && *what == 'c') {  /* found a constant name? */
+      return;  /* 'name' already filled */
+    }
+    /* else no reasonable name found */
+  }
+  *name = "?";  /* no reasonable name found */
+}
+
+
+static int filterpc (int pc, int jmptarget) {
+  if (pc < jmptarget)  /* is code conditional (inside a jump)? */
+    return -1;  /* cannot know who sets that register */
+  else return pc;  /* current position sets that register */
+}
+
+
+/*
+** try to find last instruction before 'lastpc' that modified register 'reg'
+*/
+static int findsetreg (Proto *p, int lastpc, int reg) {
+  int pc;
+  int setreg = -1;  /* keep last instruction that changed 'reg' */
+  int jmptarget = 0;  /* any code before this address is conditional */
+  for (pc = 0; pc < lastpc; pc++) {
+    Instruction i = p->code[pc];
+    OpCode op = GET_OPCODE(i);
+    int a = GETARG_A(i);
+    switch (op) {
+      case OP_LOADNIL: {
+        int b = GETARG_B(i);
+        if (a <= reg && reg <= a + b)  /* set registers from 'a' to 'a+b' */
+          setreg = filterpc(pc, jmptarget);
+        break;
+      }
+      case OP_TFORCALL: {
+        if (reg >= a + 2)  /* affect all regs above its base */
+          setreg = filterpc(pc, jmptarget);
+        break;
+      }
+      case OP_CALL:
+      case OP_TAILCALL: {
+        if (reg >= a)  /* affect all registers above base */
+          setreg = filterpc(pc, jmptarget);
+        break;
+      }
+      case OP_JMP: {
+        int b = GETARG_sBx(i);
+        int dest = pc + 1 + b;
+        /* jump is forward and do not skip 'lastpc'? */
+        if (pc < dest && dest <= lastpc) {
+          if (dest > jmptarget)
+            jmptarget = dest;  /* update 'jmptarget' */
+        }
+        break;
+      }
+      default:
+        if (testAMode(op) && reg == a)  /* any instruction that set A */
+          setreg = filterpc(pc, jmptarget);
+        break;
+    }
+  }
+  return setreg;
+}
+
+
+static const char *getobjname (Proto *p, int lastpc, int reg,
+                               const char **name) {
+  int pc;
+  *name = luaF_getlocalname(p, reg + 1, lastpc);
+  if (*name)  /* is a local? */
+    return "local";
+  /* else try symbolic execution */
+  pc = findsetreg(p, lastpc, reg);
+  if (pc != -1) {  /* could find instruction? */
+    Instruction i = p->code[pc];
+    OpCode op = GET_OPCODE(i);
+    switch (op) {
+      case OP_MOVE: {
+        int b = GETARG_B(i);  /* move from 'b' to 'a' */
+        if (b < GETARG_A(i))
+          return getobjname(p, pc, b, name);  /* get name for 'b' */
+        break;
+      }
+      case OP_GETTABUP:
+      case OP_GETTABLE: {
+        int k = GETARG_C(i);  /* key index */
+        int t = GETARG_B(i);  /* table index */
+        const char *vn = (op == OP_GETTABLE)  /* name of indexed variable */
+                         ? luaF_getlocalname(p, t + 1, pc)
+                         : upvalname(p, t);
+        kname(p, pc, k, name);
+        return (vn && strcmp(vn, LUA_ENV) == 0) ? "global" : "field";
+      }
+      case OP_GETUPVAL: {
+        *name = upvalname(p, GETARG_B(i));
+        return "upvalue";
+      }
+      case OP_LOADK:
+      case OP_LOADKX: {
+        int b = (op == OP_LOADK) ? GETARG_Bx(i)
+                                 : GETARG_Ax(p->code[pc + 1]);
+        if (ttisstring(&p->k[b])) {
+          *name = svalue(&p->k[b]);
+          return "constant";
+        }
+        break;
+      }
+      case OP_SELF: {
+        int k = GETARG_C(i);  /* key index */
+        kname(p, pc, k, name);
+        return "method";
+      }
+      default: break;  /* go through to return NULL */
+    }
+  }
+  return NULL;  /* could not find reasonable name */
+}
+
+
+/*
+** Try to find a name for a function based on the code that called it.
+** (Only works when function was called by a Lua function.)
+** Returns what the name is (e.g., "for iterator", "method",
+** "metamethod") and sets '*name' to point to the name.
+*/
+static const char *funcnamefromcode (lua_State *L, CallInfo *ci,
+                                     const char **name) {
+  TMS tm = (TMS)0;  /* (initial value avoids warnings) */
+  Proto *p = ci_func(ci)->p;  /* calling function */
+  int pc = currentpc(ci);  /* calling instruction index */
+  Instruction i = p->code[pc];  /* calling instruction */
+  if (ci->callstatus & CIST_HOOKED) {  /* was it called inside a hook? */
+    *name = "?";
+    return "hook";
+  }
+  switch (GET_OPCODE(i)) {
+    case OP_CALL:
+    case OP_TAILCALL:
+      return getobjname(p, pc, GETARG_A(i), name);  /* get function name */
+    case OP_TFORCALL: {  /* for iterator */
+      *name = "for iterator";
+       return "for iterator";
+    }
+    /* other instructions can do calls through metamethods */
+    case OP_SELF: case OP_GETTABUP: case OP_GETTABLE:
+      tm = TM_INDEX;
+      break;
+    case OP_SETTABUP: case OP_SETTABLE:
+      tm = TM_NEWINDEX;
+      break;
+    case OP_ADD: case OP_SUB: case OP_MUL: case OP_MOD:
+    case OP_POW: case OP_DIV: case OP_IDIV: case OP_BAND:
+    case OP_BOR: case OP_BXOR: case OP_SHL: case OP_SHR: {
+      int offset = cast_int(GET_OPCODE(i)) - cast_int(OP_ADD);  /* ORDER OP */
+      tm = cast(TMS, offset + cast_int(TM_ADD));  /* ORDER TM */
+      break;
+    }
+    case OP_UNM: tm = TM_UNM; break;
+    case OP_BNOT: tm = TM_BNOT; break;
+    case OP_LEN: tm = TM_LEN; break;
+    case OP_CONCAT: tm = TM_CONCAT; break;
+    case OP_EQ: tm = TM_EQ; break;
+    case OP_LT: tm = TM_LT; break;
+    case OP_LE: tm = TM_LE; break;
+    default:
+      return NULL;  /* cannot find a reasonable name */
+  }
+  *name = getstr(G(L)->tmname[tm]);
+  return "metamethod";
+}
+
+/* }====================================================== */
+
+
+
+/*
+** The subtraction of two potentially unrelated pointers is
+** not ISO C, but it should not crash a program; the subsequent
+** checks are ISO C and ensure a correct result.
+*/
+static int isinstack (CallInfo *ci, const TValue *o) {
+  ptrdiff_t i = o - ci->u.l.base;
+  return (0 <= i && i < (ci->top - ci->u.l.base) && ci->u.l.base + i == o);
+}
+
+
+/*
+** Checks whether value 'o' came from an upvalue. (That can only happen
+** with instructions OP_GETTABUP/OP_SETTABUP, which operate directly on
+** upvalues.)
+*/
+static const char *getupvalname (CallInfo *ci, const TValue *o,
+                                 const char **name) {
+  LClosure *c = ci_func(ci);
+  int i;
+  for (i = 0; i < c->nupvalues; i++) {
+    if (c->upvals[i]->v == o) {
+      *name = upvalname(c->p, i);
+      return "upvalue";
+    }
+  }
+  return NULL;
+}
+
+
+static const char *varinfo (lua_State *L, const TValue *o) {
+  const char *name = NULL;  /* to avoid warnings */
+  CallInfo *ci = L->ci;
+  const char *kind = NULL;
+  if (isLua(ci)) {
+    kind = getupvalname(ci, o, &name);  /* check whether 'o' is an upvalue */
+    if (!kind && isinstack(ci, o))  /* no? try a register */
+      kind = getobjname(ci_func(ci)->p, currentpc(ci),
+                        cast_int(o - ci->u.l.base), &name);
+  }
+  return (kind) ? luaO_pushfstring(L, " (%s '%s')", kind, name) : "";
+}
+
+
+l_noret luaG_typeerror (lua_State *L, const TValue *o, const char *op) {
+  const char *t = luaT_objtypename(L, o);
+  luaG_runerror(L, "attempt to %s a %s value%s", op, t, varinfo(L, o));
+}
+
+
+l_noret luaG_concaterror (lua_State *L, const TValue *p1, const TValue *p2) {
+  if (ttisstring(p1) || cvt2str(p1)) p1 = p2;
+  luaG_typeerror(L, p1, "concatenate");
+}
+
+
+l_noret luaG_opinterror (lua_State *L, const TValue *p1,
+                         const TValue *p2, const char *msg) {
+  lua_Number temp;
+  if (!tonumber(p1, &temp))  /* first operand is wrong? */
+    p2 = p1;  /* now second is wrong */
+  luaG_typeerror(L, p2, msg);
+}
+
+
+/*
+** Error when both values are convertible to numbers, but not to integers
+*/
+l_noret luaG_tointerror (lua_State *L, const TValue *p1, const TValue *p2) {
+  lua_Integer temp;
+  if (!tointeger(p1, &temp))
+    p2 = p1;
+  luaG_runerror(L, "number%s has no integer representation", varinfo(L, p2));
+}
+
+
+l_noret luaG_ordererror (lua_State *L, const TValue *p1, const TValue *p2) {
+  const char *t1 = luaT_objtypename(L, p1);
+  const char *t2 = luaT_objtypename(L, p2);
+  if (strcmp(t1, t2) == 0)
+    luaG_runerror(L, "attempt to compare two %s values", t1);
+  else
+    luaG_runerror(L, "attempt to compare %s with %s", t1, t2);
+}
+
+
+/* add src:line information to 'msg' */
+const char *luaG_addinfo (lua_State *L, const char *msg, TString *src,
+                                        int line) {
+  char buff[LUA_IDSIZE];
+  if (src)
+    luaO_chunkid(buff, getstr(src), LUA_IDSIZE);
+  else {  /* no source available; use "?" instead */
+    buff[0] = '?'; buff[1] = '\0';
+  }
+  return luaO_pushfstring(L, "%s:%d: %s", buff, line, msg);
+}
+
+
+l_noret luaG_errormsg (lua_State *L) {
+  if (L->errfunc != 0) {  /* is there an error handling function? */
+    StkId errfunc = restorestack(L, L->errfunc);
+    setobjs2s(L, L->top, L->top - 1);  /* move argument */
+    setobjs2s(L, L->top - 1, errfunc);  /* push function */
+    L->top++;  /* assume EXTRA_STACK */
+    luaD_callnoyield(L, L->top - 2, 1);  /* call it */
+  }
+  luaD_throw(L, LUA_ERRRUN);
+}
+
+
+l_noret luaG_runerror (lua_State *L, const char *fmt, ...) {
+  CallInfo *ci = L->ci;
+  const char *msg;
+  va_list argp;
+  luaC_checkGC(L);  /* error message uses memory */
+  va_start(argp, fmt);
+  msg = luaO_pushvfstring(L, fmt, argp);  /* format message */
+  va_end(argp);
+  if (isLua(ci))  /* if Lua function, add source:line information */
+    luaG_addinfo(L, msg, ci_func(ci)->p->source, currentline(ci));
+  luaG_errormsg(L);
+}
+
+
+void luaG_traceexec (lua_State *L) {
+  CallInfo *ci = L->ci;
+  lu_byte mask = L->hookmask;
+  int counthook = (--L->hookcount == 0 && (mask & LUA_MASKCOUNT));
+  if (counthook)
+    resethookcount(L);  /* reset count */
+  else if (!(mask & LUA_MASKLINE))
+    return;  /* no line hook and count != 0; nothing to be done */
+  if (ci->callstatus & CIST_HOOKYIELD) {  /* called hook last time? */
+    ci->callstatus &= ~CIST_HOOKYIELD;  /* erase mark */
+    return;  /* do not call hook again (VM yielded, so it did not move) */
+  }
+  if (counthook)
+    luaD_hook(L, LUA_HOOKCOUNT, -1);  /* call count hook */
+  if (mask & LUA_MASKLINE) {
+    Proto *p = ci_func(ci)->p;
+    int npc = pcRel(ci->u.l.savedpc, p);
+    int newline = getfuncline(p, npc);
+    if (npc == 0 ||  /* call linehook when enter a new function, */
+        ci->u.l.savedpc <= L->oldpc ||  /* when jump back (loop), or when */
+        newline != getfuncline(p, pcRel(L->oldpc, p)))  /* enter a new line */
+      luaD_hook(L, LUA_HOOKLINE, newline);  /* call line hook */
+  }
+  L->oldpc = ci->u.l.savedpc;
+  if (L->status == LUA_YIELD) {  /* did hook yield? */
+    if (counthook)
+      L->hookcount = 1;  /* undo decrement to zero */
+    ci->u.l.savedpc--;  /* undo increment (resume will increment it again) */
+    ci->callstatus |= CIST_HOOKYIELD;  /* mark that it yielded */
+    ci->func = L->top - 1;  /* protect stack below results */
+    luaD_throw(L, LUA_YIELD);
+  }
+}
+