From 1d5b885437286a307a77b5d12756d73d374efd54 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 20 Dec 2017 12:58:05 -0200
Subject: when running Lua code, there is no need to keep 'L->top' "correct";
 set it only when needed.

---
 ltm.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

(limited to 'ltm.c')

diff --git a/ltm.c b/ltm.c
index 5906a2fd..d41ab98d 100644
--- a/ltm.c
+++ b/ltm.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ltm.c,v 2.53 2017/12/15 13:07:10 roberto Exp roberto $
+** $Id: ltm.c,v 2.54 2017/12/19 16:40:17 roberto Exp roberto $
 ** Tag methods
 ** See Copyright Notice in lua.h
 */
@@ -101,12 +101,12 @@ const char *luaT_objtypename (lua_State *L, const TValue *o) {
 
 void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1,
                   const TValue *p2, const TValue *p3) {
-  StkId func = L->top;
+  StkId func = (isLuacode(L->ci)) ? L->ci->top : L->top;
   setobj2s(L, func, f);  /* push function (assume EXTRA_STACK) */
   setobj2s(L, func + 1, p1);  /* 1st argument */
   setobj2s(L, func + 2, p2);  /* 2nd argument */
   setobj2s(L, func + 3, p3);  /* 3rd argument */
-  L->top += 4;
+  L->top = func + 4;
   /* metamethod may yield only when called from Lua code */
   if (isLuacode(L->ci))
     luaD_call(L, func, 0);
@@ -115,8 +115,8 @@ void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1,
 }
 
 
-void luaT_callTMres (lua_State *L, const TValue *f, const TValue *p1,
-                     const TValue *p2, StkId res) {
+static void reallycallTMres (lua_State *L, const TValue *f, const TValue *p1,
+                             const TValue *p2, StkId res) {
   ptrdiff_t result = savestack(L, res);
   StkId func = L->top;
   setobj2s(L, func, f);  /* push function (assume EXTRA_STACK) */
@@ -129,7 +129,15 @@ void luaT_callTMres (lua_State *L, const TValue *f, const TValue *p1,
   else
     luaD_callnoyield(L, func, 1);
   res = restorestack(L, result);
-  setobjs2s(L, res, --L->top);  /* more result to its place */
+  setobjs2s(L, res, --L->top);  /* move result to its place */
+}
+
+
+void luaT_callTMres (lua_State *L, const TValue *f, const TValue *p1,
+                     const TValue *p2, StkId res) {
+  if (isLuacode(L->ci))
+    L->top = L->ci->top;  /* prepare top */
+  reallycallTMres(L, f, p1, p2, res);
 }
 
 
@@ -139,13 +147,15 @@ static int callbinTM (lua_State *L, const TValue *p1, const TValue *p2,
   if (ttisnil(tm))
     tm = luaT_gettmbyobj(L, p2, event);  /* try second operand */
   if (ttisnil(tm)) return 0;
-  luaT_callTMres(L, tm, p1, p2, res);
+  reallycallTMres(L, tm, p1, p2, res);
   return 1;
 }
 
 
 void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2,
                     StkId res, TMS event) {
+  if (event != TM_CONCAT && isLuacode(L->ci))
+    L->top = L->ci->top;  /* prepare top */
   if (!callbinTM(L, p1, p2, res, event)) {
     switch (event) {
       case TM_CONCAT:
@@ -185,6 +195,8 @@ void luaT_trybiniTM (lua_State *L, const TValue *p1, int i2,
 
 int luaT_callorderTM (lua_State *L, const TValue *p1, const TValue *p2,
                       TMS event) {
+  if (isLuacode(L->ci))
+    L->top = L->ci->top;  /* prepare top */
   if (callbinTM(L, p1, p2, L->top, event))  /* try original event */
     return !l_isfalse(s2v(L->top));
   else if (event == TM_LE) {
-- 
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