From 510f88d468b8a6d6feb02890417a7261073bcd87 Mon Sep 17 00:00:00 2001
From: Mike Pall <mike>
Date: Thu, 4 Jul 2024 00:13:58 +0200
Subject: [PATCH] Add build flag LUAJIT_DISABLE_TAILCALL to disable tailcall
 generation.

Only use this for debugging purposes. NEVER set it for regular builds
or distro builds! In Lua, tailcalls are a language guarantee.
Suggested by Steve Vermeulen. #1220
---
 src/lj_parse.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/lj_parse.c b/src/lj_parse.c
index db3ce8e7..4fdd4c65 100644
--- a/src/lj_parse.c
+++ b/src/lj_parse.c
@@ -2339,11 +2339,15 @@ static void parse_return(LexState *ls)
     BCReg nret = expr_list(ls, &e);
     if (nret == 1) {  /* Return one result. */
       if (e.k == VCALL) {  /* Check for tail call. */
+#ifdef LUAJIT_DISABLE_TAILCALL
+	goto notailcall;
+#else
 	BCIns *ip = bcptr(fs, &e);
 	/* It doesn't pay off to add BC_VARGT just for 'return ...'. */
 	if (bc_op(*ip) == BC_VARG) goto notailcall;
 	fs->pc--;
 	ins = BCINS_AD(bc_op(*ip)-BC_CALL+BC_CALLT, bc_a(*ip), bc_c(*ip));
+#endif
       } else {  /* Can return the result from any register. */
 	ins = BCINS_AD(BC_RET1, expr_toanyreg(fs, &e), 2);
       }