From ded2ad2d86f44424c6b6e12bf1b75836cfa9e502 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Fri, 16 May 2025 14:51:07 -0300
Subject: [PATCH] Slightly faster way to check for "global"

---
 llex.c    | 20 ++++++++++----------
 llex.h    |  1 +
 lparser.c |  4 ++--
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/llex.c b/llex.c
index 54e7f343..f8bb3ea4 100644
--- a/llex.c
+++ b/llex.c
@@ -40,16 +40,11 @@
 
 #define currIsNewline(ls)	(ls->current == '\n' || ls->current == '\r')
 
-#if defined(LUA_COMPAT_GLOBAL)
-#define GLOBALLEX	".g"	/* anything not recognizable as a name */
-#else
-#define GLOBALLEX	"global"
-#endif
 
 /* ORDER RESERVED */
 static const char *const luaX_tokens [] = {
     "and", "break", "do", "else", "elseif",
-    "end", "false", "for", "function", GLOBALLEX, "goto", "if",
+    "end", "false", "for", "function", "global", "goto", "if",
     "in", "local", "nil", "not", "or", "repeat",
     "return", "then", "true", "until", "while",
     "//", "..", "...", "==", ">=", "<=", "~=",
@@ -189,10 +184,15 @@ void luaX_setinput (lua_State *L, LexState *ls, ZIO *z, TString *source,
   ls->linenumber = 1;
   ls->lastline = 1;
   ls->source = source;
-  ls->envn = luaS_newliteral(L, LUA_ENV);  /* get env name */
-  ls->brkn = luaS_newliteral(L, "break");  /* get "break" name */
-  /* "break" cannot be collected, as it is a reserved word" */
-  lua_assert(isreserved(ls->brkn));
+  /* all three strings here ("_ENV", "break", "global") were fixed,
+     so they cannot be collected */
+  ls->envn = luaS_newliteral(L, LUA_ENV);  /* get env string */
+  ls->brkn = luaS_newliteral(L, "break");  /* get "break" string */
+#if defined(LUA_COMPAT_GLOBAL)
+  /* compatibility mode: "global" is not a reserved word */
+  ls->glbn = luaS_newliteral(L, "global");  /* get "global" string */
+  ls->glbn->extra = 0;  /* mark it as not reserved */
+#endif
   luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER);  /* initialize buffer */
 }
 
diff --git a/llex.h b/llex.h
index 0dba9d60..37016e8a 100644
--- a/llex.h
+++ b/llex.h
@@ -76,6 +76,7 @@ typedef struct LexState {
   TString *source;  /* current source name */
   TString *envn;  /* environment variable name */
   TString *brkn;  /* "break" name (used as a label) */
+  TString *glbn;  /* "global" name (when not a reserved word) */
 } LexState;
 
 
diff --git a/lparser.c b/lparser.c
index 29022bfd..384ef690 100644
--- a/lparser.c
+++ b/lparser.c
@@ -2001,10 +2001,10 @@ static void statement (LexState *ls) {
     case TK_NAME: {
       /* compatibility code to parse global keyword when "global"
          is not reserved */
-      if (strcmp(getstr(ls->t.seminfo.ts), "global") == 0) {
+      if (ls->t.seminfo.ts == ls->glbn) {  /* current = "global"? */
         int lk = luaX_lookahead(ls);
         if (lk == TK_NAME || lk == '*' || lk == TK_FUNCTION) {
-          /* 'global <name>' or 'global *' or 'global function' */
+          /* 'global name' or 'global *' or 'global function' */
           globalstatfunc(ls, line);
           break;
         }