Cleaning 'luaP_isIT' and 'luaP_isOT'

- 'luaP_isOT' is only used for tests, so it is defined as a macro to avoid
wasting space with an unused function.
- 'luaP_isIT' must include OP_VARARGPREP.

lopcodes.c

@@ -109,30 +109,21 @@ LUAI_DDEF const lu_byte luaP_opmodes[NUM_OPCODES] = {
 };
 
 
-
-/*
-** Check whether instruction sets top for next instruction, that is,
-** it results in multiple values.
-*/
-int luaP_isOT (Instruction i) {
-  OpCode op = GET_OPCODE(i);
-  switch (op) {
-    case OP_TAILCALL: return 1;
-    default:
-      return testOTMode(op) && GETARG_C(i) == 0;
-  }
-}
+#define testITMode(m)	(luaP_opmodes[m] & (1 << 5))
 
 
 /*
-** Check whether instruction uses top from previous instruction, that is,
-** it accepts multiple results.
+** Check whether instruction uses top. That happens for OP_VARARGPREP
+** and for instructions that use multiple values set by the previous
+** instruction.
 */
 int luaP_isIT (Instruction i) {
   OpCode op = GET_OPCODE(i);
   switch (op) {
     case OP_SETLIST:
-      return testITMode(GET_OPCODE(i)) && GETARG_vB(i) == 0;
+      return GETARG_vB(i) == 0;
+    case OP_VARARGPREP:
+      return 1;
     default:
       return testITMode(GET_OPCODE(i)) && GETARG_B(i) == 0;
   }