optimization for tailcall does not seem to pay itself

lcode.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lcode.c,v 1.63 2001/02/23 17:17:25 roberto Exp roberto $
+** $Id: lcode.c,v 1.64 2001/02/23 20:28:19 roberto Exp roberto $
 ** Code generator for Lua
 ** See Copyright Notice in lua.h
 */
@@ -482,14 +482,6 @@ int luaK_code2 (FuncState *fs, OpCode o, int arg1, int arg2) {
       pop = 2*arg1;
       break;
     }
-    case OP_RETURN: {
-      if (GET_OPCODE(i) == OP_CALL && GETARG_B(i) == MULT_RET) {
-        SET_OPCODE(i, OP_TAILCALL);
-        SETARG_B(i, arg1);
-        optm = 1;
-      }
-      break;
-    }
     case OP_PUSHNIL: {
       if (arg1 == 0) return NO_JUMP;  /* nothing to do */
       push = arg1;
@@ -632,7 +624,6 @@ int luaK_code2 (FuncState *fs, OpCode o, int arg1, int arg2) {
     }
     case OP_GETDOTTED:
     case OP_GETINDEXED:
-    case OP_TAILCALL:
     case OP_ADDI: {
       lua_assert(0);  /* instruction used only for optimizations */
       break;
@@ -669,7 +660,6 @@ int luaK_code2 (FuncState *fs, OpCode o, int arg1, int arg2) {
 const OpProperties luaK_opproperties[] = {
   {iU, 0, 0},	/* OP_RETURN */
   {iAB, 0, 0},	/* OP_CALL */
-  {iAB, 0, 0},	/* OP_TAILCALL */
   {iU, VD, 0},	/* OP_PUSHNIL */
   {iU, 0, VD},	/* OP_POP */
   {iS, 1, 0},	/* OP_PUSHINT */

ldebug.c

@@ -1,5 +1,5 @@
 /*
-** $Id: ldebug.c,v 1.71 2001/03/02 17:27:50 roberto Exp roberto $
+** $Id: ldebug.c,v 1.72 2001/03/06 14:46:54 roberto Exp roberto $
 ** Debug Interface
 ** See Copyright Notice in lua.h
 */
@@ -405,11 +405,6 @@ static Instruction luaG_symbexec (lua_State *L, const Proto *pt,
         push = arg2;
         break;
       }
-      case OP_TAILCALL: {
-        check(arg1 < top && arg2 <= top);
-        pop = top-arg2;
-        break;
-      }
       case OP_PUSHNIL: {
         check(arg1 > 0);
         push = arg1;
@@ -585,12 +580,9 @@ static const l_char *getfuncname (lua_State *L, StkId f, const l_char **name) {
     Instruction i;
     if (pc == -1) return NULL;  /* function is not activated */
     i = p->code[pc];
-    switch (GET_OPCODE(i)) {
-      case OP_CALL: case OP_TAILCALL:
-        return getobjname(L, (func+1)+GETARG_A(i), name);
-      default:
-        return NULL;  /* no useful name found */
-    }
+    return (GET_OPCODE(i) == OP_CALL
+             ? getobjname(L, (func+1)+GETARG_A(i), name)
+             : NULL);  /* no useful name found */
   }
 }
 

lopcodes.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lopcodes.h,v 1.69 2000/12/04 18:33:40 roberto Exp roberto $
+** $Id: lopcodes.h,v 1.70 2001/01/15 16:13:24 roberto Exp roberto $
 ** Opcodes for Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -85,7 +85,6 @@ name		args	stack before	stack after	side effects
 OP_RETURN,/*	U	v_n-v_x(at u)	(return)	returns v_x-v_n	*/
 
 OP_CALL,/*	A B	v_n-v_1 f(at a)	r_b-r_1		f(v1,...,v_n)	*/
-OP_TAILCALL,/*	A B	v_n-v_1 f(at a)	(return)	f(v1,...,v_n)	*/
 
 OP_PUSHNIL,/*	U	-		nil_1-nil_u			*/
 OP_POP,/*	U	a_u-a_1		-				*/

ltests.c

@@ -1,5 +1,5 @@
 /*
-** $Id: ltests.c,v 1.73 2001/03/02 17:27:50 roberto Exp roberto $
+** $Id: ltests.c,v 1.74 2001/03/06 20:09:38 roberto Exp roberto $
 ** Internal Module for Debugging of the Lua Implementation
 ** See Copyright Notice in lua.h
 */
@@ -139,14 +139,53 @@ void *debug_realloc (void *block, size_t oldsize, size_t size) {
 
 
 static const l_char *const instrname[NUM_OPCODES] = {
-  l_s("RETURN"), l_s("CALL"), l_s("TAILCALL"), l_s("PUSHNIL"), l_s("POP"), l_s("PUSHINT"), 
-  l_s("PUSHSTRING"), l_s("PUSHNUM"), l_s("PUSHNEGNUM"), l_s("PUSHUPVALUE"), l_s("GETLOCAL"), 
-  l_s("GETGLOBAL"), l_s("GETTABLE"), l_s("GETDOTTED"), l_s("GETINDEXED"), l_s("PUSHSELF"), 
-  l_s("CREATETABLE"), l_s("SETLOCAL"), l_s("SETGLOBAL"), l_s("SETTABLE"), l_s("SETLIST"), l_s("SETMAP"), 
-  l_s("ADD"), l_s("ADDI"), l_s("SUB"), l_s("MULT"), l_s("DIV"), l_s("POW"), l_s("CONCAT"), l_s("MINUS"), l_s("NOT"), 
-  l_s("JMPNE"), l_s("JMPEQ"), l_s("JMPLT"), l_s("JMPLE"), l_s("JMPGT"), l_s("JMPGE"), l_s("JMPT"), l_s("JMPF"), 
-  l_s("JMPONT"), l_s("JMPONF"), l_s("JMP"), l_s("PUSHNILJMP"), l_s("FORPREP"), l_s("FORLOOP"), l_s("LFORPREP"), 
-  l_s("LFORLOOP"), l_s("CLOSURE")
+  l_s("RETURN"),
+  l_s("CALL"),
+  l_s("PUSHNIL"),
+  l_s("POP"),
+  l_s("PUSHINT"),
+  l_s("PUSHSTRING"),
+  l_s("PUSHNUM"),
+  l_s("PUSHNEGNUM"),
+  l_s("PUSHUPVALUE"),
+  l_s("GETLOCAL"),
+  l_s("GETGLOBAL"),
+  l_s("GETTABLE"),
+  l_s("GETDOTTED"),
+  l_s("GETINDEXED"),
+  l_s("PUSHSELF"),
+  l_s("CREATETABLE"),
+  l_s("SETLOCAL"),
+  l_s("SETGLOBAL"),
+  l_s("SETTABLE"),
+  l_s("SETLIST"),
+  l_s("SETMAP"),
+  l_s("ADD"),
+  l_s("ADDI"),
+  l_s("SUB"),
+  l_s("MULT"),
+  l_s("DIV"),
+  l_s("POW"),
+  l_s("CONCAT"),
+  l_s("MINUS"),
+  l_s("NOT"),
+  l_s("JMPNE"),
+  l_s("JMPEQ"),
+  l_s("JMPLT"),
+  l_s("JMPLE"),
+  l_s("JMPGT"),
+  l_s("JMPGE"),
+  l_s("JMPT"),
+  l_s("JMPF"),
+  l_s("JMPONT"),
+  l_s("JMPONF"),
+  l_s("JMP"),
+  l_s("PUSHNILJMP"),
+  l_s("FORPREP"),
+  l_s("FORLOOP"),
+  l_s("LFORPREP"),
+  l_s("LFORLOOP"),
+  l_s("CLOSURE")
 };
 
 

lvm.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 1.172 2001/02/23 17:17:25 roberto Exp roberto $
+** $Id: lvm.c,v 1.173 2001/02/23 20:30:52 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -357,11 +357,6 @@ StkId luaV_execute (lua_State *L, const Closure *cl, StkId base) {
         L->top = base+tf->maxstacksize;
         break;
       }
-      case OP_TAILCALL: {
-        L->top = top;
-        luaD_call(L, base+GETARG_A(i), LUA_MULTRET);
-        return base+GETARG_B(i);
-      }
       case OP_PUSHNIL: {
         int n = GETARG_U(i);
         lua_assert(n>0);