x64: Enable LJ_GC64 mode by default.

doc/extensions.html

@@ -208,9 +208,8 @@ bytecode (e.g. from Lua 5.1) is incompatible and cannot be loaded.
 </p>
 <p>
 Note: <tt>LJ_GC64</tt> mode requires a different frame layout, which implies
-a different, incompatible bytecode format for ports that use this mode (e.g.
-ARM64 or MIPS64) or when explicitly enabled for x64. This may be rectified
-in the future.
+a different, incompatible bytecode format for all 64 bit ports. This may be
+rectified in the future.
 </p>
 
 <h3 id="table_new"><tt>table.new(narray, nhash)</tt> allocates a pre-sized table</h3>

doc/install.html

@@ -175,12 +175,11 @@ Please read the instructions given in these files, before changing
 any settings.
 </p>
 <p>
-LuaJIT on x64 currently uses 32 bit GC objects by default.
-<tt>LJ_GC64</tt> mode may be explicitly enabled:
-add <tt>XCFLAGS=-DLUAJIT_ENABLE_GC64</tt> to the make command or run
-<tt>msvcbuild gc64</tt> for MSVC/WinSDK. Please check the note
-about the <a href="extensions.html#string_dump">bytecode format</a>
-differences, too.
+All LuaJIT 64 bit ports use 64 bit GC objects by default (<tt>LJ_GC64</tt>).
+For x64, you can select the old 32-on-64 bit mode by adding
+<tt>XCFLAGS=-DLUAJIT_DISABLE_GC64</tt> to the make command.
+Please check the note about the
+<a href="extensions.html#string_dump">bytecode format</a> differences, too.
 </p>
 
 <h2 id="posix">POSIX Systems (Linux, OSX, *BSD etc.)</h2>

src/Makefile

@@ -110,8 +110,8 @@ XCFLAGS=
 #XCFLAGS+= -DLUAJIT_NUMMODE=1
 #XCFLAGS+= -DLUAJIT_NUMMODE=2
 #
-# Enable GC64 mode for x64.
-#XCFLAGS+= -DLUAJIT_ENABLE_GC64
+# Disable LJ_GC64 mode for x64.
+#XCFLAGS+= -DLUAJIT_DISABLE_GC64
 #
 ##############################################################################
 

src/lj_arch.h

@@ -184,7 +184,7 @@
 #define LJ_TARGET_MASKROT	1
 #define LJ_TARGET_UNALIGNED	1
 #define LJ_ARCH_NUMMODE		LJ_NUMMODE_SINGLE_DUAL
-#ifdef LUAJIT_ENABLE_GC64
+#ifndef LUAJIT_DISABLE_GC64
 #define LJ_TARGET_GC64		1
 #endif
 

src/msvcbuild.bat

@@ -5,6 +5,7 @@
 @rem Then cd to this directory and run this script. Use the following
 @rem options (in order), if needed. The default is a dynamic release build.
 @rem
+@rem   nogc64   disable LJ_GC64 mode for x64
 @rem   debug    emit debug symbols
 @rem   amalg    amalgamated build
 @rem   static   static linkage
@@ -20,7 +21,7 @@
 @set LJLIB=lib /nologo /nodefaultlib
 @set DASMDIR=..\dynasm
 @set DASM=%DASMDIR%\dynasm.lua
-@set DASC=vm_x86.dasc
+@set DASC=vm_x64.dasc
 @set LJDLLNAME=lua51.dll
 @set LJLIBNAME=lua51.lib
 @set BUILDTYPE=release
@@ -37,15 +38,16 @@ if exist minilua.exe.manifest^
 @set LJARCH=x64
 @minilua
 @if errorlevel 8 goto :X64
+@set DASC=vm_x86.dasc
 @set DASMFLAGS=-D WIN -D JIT -D FFI
 @set LJARCH=x86
 @set LJCOMPILE=%LJCOMPILE% /arch:SSE2
 :X64
-@if "%1" neq "gc64" goto :NOGC64
+@if "%1" neq "nogc64" goto :GC64
 @shift
-@set DASC=vm_x64.dasc
-@set LJCOMPILE=%LJCOMPILE% /DLUAJIT_ENABLE_GC64
-:NOGC64
+@set DASC=vm_x86.dasc
+@set LJCOMPILE=%LJCOMPILE% /DLUAJIT_DISABLE_GC64
+:GC64
 minilua %DASM% -LN %DASMFLAGS% -o host\buildvm_arch.h %DASC%
 @if errorlevel 1 goto :BAD