baby steps to remove 'CallInfo': keeping 'L->func' correct

ldo.c

@@ -1,5 +1,5 @@
 /*
-** $Id: ldo.c,v 2.161 2017/06/29 15:06:44 roberto Exp roberto $
+** $Id: ldo.c,v 2.162 2017/07/27 13:50:16 roberto Exp roberto $
 ** Stack and Call structure of Lua
 ** See Copyright Notice in lua.h
 */
@@ -160,6 +160,7 @@ static void correctstack (lua_State *L, StkId oldstack) {
   CallInfo *ci;
   UpVal *up;
   L->top = (L->top - oldstack) + L->stack;
+  L->func = (L->func - oldstack) + L->stack;
   for (up = L->openupval; up != NULL; up = up->u.open.next)
     up->v = s2v((uplevel(up) - oldstack) + L->stack);
   for (ci = L->ci; ci != NULL; ci = ci->previous) {
@@ -369,6 +370,8 @@ int luaD_poscall (lua_State *L, CallInfo *ci, StkId firstResult, int nres) {
   }
   res = ci->func;  /* res == final position of 1st result */
   L->ci = ci->previous;  /* back to caller */
+  L->func -= L->func->stkci.previous;
+  lua_assert(L->func == L->ci->func);
   /* move results to proper place */
   return moveresults(L, firstResult, res, nres, wanted);
 }
@@ -400,7 +403,8 @@ int luaD_precall (lua_State *L, StkId func, int nresults) {
       checkstackp(L, LUA_MINSTACK, func);  /* ensure minimum stack size */
       ci = next_ci(L);  /* now 'enter' new function */
       ci->nresults = nresults;
-      ci->func = func;
+      func->stkci.previous = func - L->func;
+      L->func = ci->func = func;
       ci->top = L->top + LUA_MINSTACK;
       lua_assert(ci->top <= L->stack_last);
       ci->callstatus = 0;
@@ -424,7 +428,8 @@ int luaD_precall (lua_State *L, StkId func, int nresults) {
         luaT_adjustvarargs(L, p, n);
       ci = next_ci(L);  /* now 'enter' new function */
       ci->nresults = nresults;
-      ci->func = func;
+      func->stkci.previous = func - L->func;
+      L->func = ci->func = func;
       L->top = ci->top = func + 1 + fsize;
       lua_assert(ci->top <= L->stack_last);
       ci->u.l.savedpc = p->code;  /* starting point */
@@ -558,6 +563,7 @@ static int recover (lua_State *L, int status) {
   luaF_close(L, oldtop);
   seterrorobj(L, status, oldtop);
   L->ci = ci;
+  L->func = ci->func;
   L->allowhook = getoah(ci->callstatus);  /* restore original 'allowhook' */
   L->nny = 0;  /* should be zero to be yieldable */
   luaD_shrinkstack(L);
@@ -693,6 +699,7 @@ int luaD_pcall (lua_State *L, Pfunc func, void *u,
                 ptrdiff_t old_top, ptrdiff_t ef) {
   int status;
   CallInfo *old_ci = L->ci;
+  ptrdiff_t oldfunc = savestack(L, L->func);
   lu_byte old_allowhooks = L->allowhook;
   unsigned short old_nny = L->nny;
   ptrdiff_t old_errfunc = L->errfunc;
@@ -703,6 +710,7 @@ int luaD_pcall (lua_State *L, Pfunc func, void *u,
     luaF_close(L, oldtop);  /* close possible pending closures */
     seterrorobj(L, status, oldtop);
     L->ci = old_ci;
+    L->func = restorestack(L, oldfunc);
     L->allowhook = old_allowhooks;
     L->nny = old_nny;
     luaD_shrinkstack(L);

lobject.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lobject.h,v 2.124 2017/06/27 11:35:31 roberto Exp roberto $
+** $Id: lobject.h,v 2.125 2017/06/29 15:06:44 roberto Exp roberto $
 ** Type definitions for Lua objects
 ** See Copyright Notice in lua.h
 */
@@ -311,6 +311,10 @@ typedef struct TValue {
 
 typedef union StackValue {
   TValue val;
+  struct {
+    TValuefields;
+    unsigned short previous;  /* difference to previous 'func' */
+  } stkci;
 } StackValue;
 
 

lstate.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 2.141 2017/06/29 15:06:44 roberto Exp roberto $
+** $Id: lstate.c,v 2.142 2017/10/11 12:38:45 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -153,8 +153,10 @@ static void stack_init (lua_State *L1, lua_State *L) {
   ci = &L1->base_ci;
   ci->next = ci->previous = NULL;
   ci->callstatus = 0;
-  ci->func = L1->top;
-  setnilvalue(s2v(L1->top++));  /* 'function' entry for this 'ci' */
+  L1->func = ci->func = L1->top;
+  L1->func->stkci.previous = 0;  /* end of linked list */
+  setnilvalue(s2v(L1->top));  /* 'function' entry for this 'ci' */
+  L1->top++;
   ci->top = L1->top + LUA_MINSTACK;
   L1->ci = ci;
 }
@@ -215,6 +217,7 @@ static void preinit_thread (lua_State *L, global_State *g) {
   G(L) = g;
   L->stack = NULL;
   L->ci = NULL;
+  L->func = NULL;
   L->nci = 0;
   L->stacksize = 0;
   L->twups = L;  /* thread has no upvalues */

lstate.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.h,v 2.143 2017/06/12 14:21:44 roberto Exp roberto $
+** $Id: lstate.h,v 2.144 2017/07/27 13:50:16 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -192,6 +192,7 @@ struct lua_State {
   StkId top;  /* first free slot in the stack */
   global_State *l_G;
   CallInfo *ci;  /* call info for current function */
+  StkId func;  /* current function */
   const Instruction *oldpc;  /* last pc traced */
   StkId stack_last;  /* last free slot in the stack */
   StkId stack;  /* stack base */

lvm.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 2.298 2017/10/04 15:49:24 roberto Exp roberto $
+** $Id: lvm.c,v 2.299 2017/10/04 21:56:32 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -1390,6 +1390,7 @@ void luaV_execute (lua_State *L) {
           oci->u.l.savedpc = nci->u.l.savedpc;
           oci->callstatus |= CIST_TAIL;  /* function was tail called */
           ci = L->ci = oci;  /* remove new frame */
+          L->func = ofunc;
           lua_assert(L->top ==
                      oci->func + 1 + getproto(s2v(ofunc))->maxstacksize);
           goto newframe;  /* restart luaV_execute over new Lua function */