in 'luaD_poscall', there is no need to compute 'firstResult' when 'nres==0'

ldo.c

@@ -1,5 +1,5 @@
 /*
-** $Id: ldo.c,v 2.199 2018/03/07 16:26:01 roberto Exp roberto $
+** $Id: ldo.c,v 2.200 2018/03/16 15:33:34 roberto Exp roberto $
 ** Stack and Call structure of Lua
 ** See Copyright Notice in lua.h
 */
@@ -319,14 +319,15 @@ void luaD_hookcall (lua_State *L, CallInfo *ci) {
 }
 
 
-static void rethook (lua_State *L, CallInfo *ci, StkId firstres, int nres) {
+static StkId rethook (lua_State *L, CallInfo *ci, StkId firstres, int nres) {
+  ptrdiff_t oldtop = savestack(L, L->top);  /* hook may change top */
   int delta = 0;
   if (isLuacode(ci)) {
     Proto *p = clLvalue(s2v(ci->func))->p;
     if (p->is_vararg)
       delta = ci->u.l.nextraargs + p->numparams + 1;
     if (L->top < ci->top)
-      L->top = ci->top;  /* correct top */
+      L->top = ci->top;  /* correct top to run hook */
   }
   if (L->hookmask & LUA_MASKRET) {  /* is return hook on? */
     int ftransfer;
@@ -337,6 +338,7 @@ static void rethook (lua_State *L, CallInfo *ci, StkId firstres, int nres) {
   }
   if (isLua(ci->previous))
     L->oldpc = ci->previous->u.l.savedpc;  /* update 'oldpc' */
+  return restorestack(L, oldtop);
 }
 
 
@@ -363,40 +365,33 @@ void luaD_tryfuncTM (lua_State *L, StkId func) {
 ** expressions, multiple results for tail calls/single parameters)
 ** separated.
 */
-static void moveresults (lua_State *L, StkId firstResult, StkId res,
-                                       int nres, int wanted) {
+static void moveresults (lua_State *L, StkId res, int nres, int wanted) {
   switch (wanted) {  /* handle typical cases separately */
-    case 0: break;  /* nothing to move */
-    case 1: {  /* one result needed */
+    case 0:  /* no values needed */
+      L->top = res;
+      break;
+    case 1:  /* one value needed */
       if (nres == 0)   /* no results? */
         setnilvalue(s2v(res));  /* adjust with nil */
       else
-        setobjs2s(L, res, firstResult);  /* move it to proper place */
+        setobjs2s(L, res, L->top - nres);  /* move it to proper place */
+      L->top = res + 1;
       break;
-    }
-    case LUA_MULTRET: {
+    case LUA_MULTRET:
+      wanted = nres;  /* we want all results */
+      /* FALLTHROUGH */
+    default: {  /* multiple results */
+      StkId firstresult = L->top - nres;  /* index of first result */
       int i;
-      for (i = 0; i < nres; i++)  /* move all results to correct place */
-        setobjs2s(L, res + i, firstResult + i);
-      wanted = nres;  /* it wanted what it had */
-      break;
-    }
-    default: {
-      int i;
-      if (wanted <= nres) {  /* enough results? */
-        for (i = 0; i < wanted; i++)  /* move wanted results to correct place */
-          setobjs2s(L, res + i, firstResult + i);
-      }
-      else {  /* not enough results; use all of them plus nils */
-        for (i = 0; i < nres; i++)  /* move all results to correct place */
-          setobjs2s(L, res + i, firstResult + i);
-        for (; i < wanted; i++)  /* complete wanted number of results */
-          setnilvalue(s2v(res + i));
-      }
+      /* move all results to correct place */
+      for (i = 0; i < nres && i < wanted; i++)
+        setobjs2s(L, res + i, firstresult + i);
+      for (; i < wanted; i++)  /* complete wanted number of results */
+        setnilvalue(s2v(res + i));
+      L->top = res + wanted;  /* top points after the last result */
       break;
     }
   }
-  L->top = res + wanted;  /* top points after the last result */
 }
 
 
@@ -404,15 +399,12 @@ static void moveresults (lua_State *L, StkId firstResult, StkId res,
 ** Finishes a function call: calls hook if necessary, removes CallInfo,
 ** moves current number of results to proper place.
 */
-void luaD_poscall (lua_State *L, CallInfo *ci, StkId firstResult, int nres) {
-  if (L->hookmask) {
-    ptrdiff_t fr = savestack(L, firstResult);  /* hook may change stack */
-    rethook(L, ci, firstResult, nres);
-    firstResult = restorestack(L, fr);
-  }
+void luaD_poscall (lua_State *L, CallInfo *ci, int nres) {
+  if (L->hookmask)
+    L->top = rethook(L, ci, L->top - nres, nres);
   L->ci = ci->previous;  /* back to caller */
   /* move results to proper place */
-  moveresults(L, firstResult, ci->func, nres, ci->nresults);
+  moveresults(L, ci->func, nres, ci->nresults);
 }
 
 
@@ -477,7 +469,7 @@ void luaD_call (lua_State *L, StkId func, int nresults) {
       n = (*f)(L);  /* do the actual call */
       lua_lock(L);
       api_checknelems(L, n);
-      luaD_poscall(L, ci, L->top - n, n);
+      luaD_poscall(L, ci, n);
       break;
     }
     case LUA_TLCL: {  /* Lua function */
@@ -540,7 +532,7 @@ static void finishCcall (lua_State *L, int status) {
   n = (*ci->u.c.k)(L, status, ci->u.c.ctx);  /* call continuation function */
   lua_lock(L);
   api_checknelems(L, n);
-  luaD_poscall(L, ci, L->top - n, n);  /* finish 'luaD_call' */
+  luaD_poscall(L, ci, n);  /* finish 'luaD_call' */
 }
 
 
@@ -642,9 +634,8 @@ static void resume (lua_State *L, void *ud) {
         n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */
         lua_lock(L);
         api_checknelems(L, n);
-        firstArg = L->top - n;  /* yield results come from continuation */
       }
-      luaD_poscall(L, ci, firstArg, n);  /* finish 'luaD_call' */
+      luaD_poscall(L, ci, n);  /* finish 'luaD_call' */
     }
     unroll(L, NULL);  /* run continuation */
   }

ldo.h

@@ -1,5 +1,5 @@
 /*
-** $Id: ldo.h,v 2.42 2018/02/15 15:34:29 roberto Exp roberto $
+** $Id: ldo.h,v 2.43 2018/02/17 19:29:29 roberto Exp roberto $
 ** Stack and Call structure of Lua
 ** See Copyright Notice in lua.h
 */
@@ -61,8 +61,7 @@ LUAI_FUNC void luaD_callnoyield (lua_State *L, StkId func, int nResults);
 LUAI_FUNC void luaD_tryfuncTM (lua_State *L, StkId func);
 LUAI_FUNC int luaD_pcall (lua_State *L, Pfunc func, void *u,
                                         ptrdiff_t oldtop, ptrdiff_t ef);
-LUAI_FUNC void luaD_poscall (lua_State *L, CallInfo *ci, StkId firstResult,
-                                          int nres);
+LUAI_FUNC void luaD_poscall (lua_State *L, CallInfo *ci, int nres);
 LUAI_FUNC int luaD_reallocstack (lua_State *L, int newsize, int raiseerror);
 LUAI_FUNC int luaD_growstack (lua_State *L, int n, int raiseerror);
 LUAI_FUNC void luaD_shrinkstack (lua_State *L);

lvm.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 2.353 2018/04/04 14:23:41 roberto Exp roberto $
+** $Id: lvm.c,v 2.354 2018/05/02 18:17:59 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -1591,7 +1591,7 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
             ra = RA(i);
           }
           ci->func -= delta;
-          luaD_poscall(L, ci, ra, cast_int(L->top - ra));
+          luaD_poscall(L, ci, cast_int(L->top - ra));
           return;
         }
         else {  /* Lua tail call */
@@ -1602,20 +1602,25 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         vmbreak;
       }
       vmcase(OP_RETURN) {
-        int b = GETARG_B(i);
-        int n = (b != 0 ? b - 1 : cast_int(L->top - ra));
+        int n = GETARG_B(i) - 1;  /* number of results */
+        if (n < 0)  /* not fixed? */
+          n = cast_int(L->top - ra);  /* get what is available */
+        else
+          L->top = ra + n;  /* set call for 'luaD_poscall' */
         if (TESTARG_k(i)) {
           int nparams1 = GETARG_C(i);
           if (nparams1)  /* vararg function? */
             ci->func -= ci->u.l.nextraargs + nparams1;
           luaF_close(L, base);  /* there may be open upvalues */
         }
-        halfProtect(luaD_poscall(L, ci, ra, n));
+        halfProtect(luaD_poscall(L, ci, n));
         return;
       }
       vmcase(OP_RETURN0) {
-        if (L->hookmask)
-          halfProtect(luaD_poscall(L, ci, ra, 0));  /* no hurry... */
+        if (L->hookmask) {
+          L->top = ra;
+          halfProtect(luaD_poscall(L, ci, 0));  /* no hurry... */
+        }
         else {
           int nres = ci->nresults;
           L->ci = ci->previous;  /* back to caller */
@@ -1626,8 +1631,10 @@ void luaV_execute (lua_State *L, CallInfo *ci) {
         return;
       }
       vmcase(OP_RETURN1) {
-        if (L->hookmask)
-          halfProtect(luaD_poscall(L, ci, ra, 1));  /* no hurry... */
+        if (L->hookmask) {
+          L->top = ra + 1;
+          halfProtect(luaD_poscall(L, ci, 1));  /* no hurry... */
+        }
         else {
           int nres = ci->nresults;
           L->ci = ci->previous;  /* back to caller */