From 9bf6888aa859115458df49af3fddd5968df5476c Mon Sep 17 00:00:00 2001
From: Dekkonot <git@dekkonot.com>
Date: Tue, 17 Oct 2023 14:25:18 -0700
Subject: [PATCH] Use fast flags correctly

---
 Compiler/src/Builtins.cpp | 7 ++-----
 VM/src/lbitlib.cpp        | 8 +++++---
 2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/Compiler/src/Builtins.cpp b/Compiler/src/Builtins.cpp
index d1c29d45..14cfd168 100644
--- a/Compiler/src/Builtins.cpp
+++ b/Compiler/src/Builtins.cpp
@@ -4,7 +4,7 @@
 #include "Luau/Bytecode.h"
 #include "Luau/Compiler.h"
 
-LUAU_FASTFLAG(LuauBit32ByteswapBuiltin)
+LUAU_FASTFLAGVARIABLE(LuauBit32ByteswapBuiltin, true)
 
 namespace Luau
 {
@@ -168,11 +168,8 @@ static int getBuiltinFunctionId(const Builtin& builtin, const CompileOptions& op
             return LBF_BIT32_COUNTLZ;
         if (builtin.method == "countrz")
             return LBF_BIT32_COUNTRZ;
-        if (builtin.method == "byteswap")
-        {
-            LUAU_ASSERT(FFlag::LuauBit32ByteswapBuiltin);
+        if (FFlag::LuauBit32ByteswapBuiltin && builtin.method == "byteswap")
             return LBF_BIT32_BYTESWAP;
-        }
     }
 
     if (builtin.object == "string")
diff --git a/VM/src/lbitlib.cpp b/VM/src/lbitlib.cpp
index 65572501..f69b23ce 100644
--- a/VM/src/lbitlib.cpp
+++ b/VM/src/lbitlib.cpp
@@ -5,7 +5,7 @@
 #include "lcommon.h"
 #include "lnumutils.h"
 
-LUAU_FASTFLAG(LuauBit32Byteswap)
+LUAU_FASTFLAGVARIABLE(LuauBit32Byteswap, true)
 
 #define ALLONES ~0u
 #define NBITS int(8 * sizeof(unsigned))
@@ -214,9 +214,11 @@ static int b_countrz(lua_State* L)
 
 static int b_swap(lua_State* L)
 {
-    LUAU_ASSERT(FFlag::LuauBit32Byteswap);
+    if (!FFlag::LuauBit32Byteswap)
+        luaL_error(L, "bit32.byteswap isn't enabled");
+
     b_uint n = luaL_checkunsigned(L, 1);
-    n = ((n >> 24) & 0xff) | ((n << 8) & 0xff0000) | ((n >> 8) & 0xff00) | ((n << 24) & 0xff000000);
+    n = (n << 24) | ((n << 8) & 0xff0000) | (n >> 8 & 0xff00) | n >> 24;
 
     lua_pushunsigned(L, n);
     return 1;