Re: LuaJIT vs C++

["Alex Davies" <alex.mania@...>]

Hey,

I run luajit under Delphi, which also cannot run setjmp/longjmp due to 
finalizers. My approach was to compile it as C code, but replace uses of 
LUAI_TRY with a function that calls Delphi_Try. (and define the LUAI_THROW 
macro as one that simply raises a delphi exception). I never had any 
problems with Jit, but I do not use or require coroutines. However error 
handling works fine. You could try that?

Delphi_Try:

procedure Delphi_Try(L: TLua; var Status: Integer; F: FLuaProcCall; UD: 
Pointer);
begin
 try
   func(L, UD);
 except
   if status = 0 then
     status := -1;
 end;
end;

(The function is a little bit different to that, as I have it that regular 
delphi exceptions are converted in to lua errors);

----- Original Message ----- 
From: "Alexander Gladysh"
> Hi, list!
>
> We have an application, dynamically linked with Lua. Lua is compiled
> as C++ code to allow us to write our bindings in C++.
>
> As you know, compiling Lua as C++ basically changes longjmp() in
> LUAI_THROW to throw; and setjmp() in LUAI_TRY to try {} catch() {}.
> This change is crucial as longjmp/setjmp basically do not call any
> destructors in C++ objects.
>
> Now we're considering a switch to LuaJIT. Vanilla LuaJIT does not
> compile as C++.
>
> To compile it successfully under GCC, we had to do two things:
>
> 1. Fix goto jump across variable initialization in jit_coroutine_resume():
>
> diff --git a/gamed/libs/luajit/src/ljit_x86.h 
> b/gamed/libs/luajit/src/ljit_x86.h
> index 329b3f0..d0d0160 100644
> --- a/gamed/libs/luajit/src/ljit_x86.h
> +++ b/gamed/libs/luajit/src/ljit_x86.h
> @@ -607,6 +607,10 @@ static void jit_inline_base(jit_State *J,
> jit_InlineInfo *ii)
> /* Helper function for inlined coroutine.resume(). */
> static StkId jit_coroutine_resume(lua_State *L, StkId base, int nresults)
> {
> +  unsigned int ndelta = 0;
> +  int nargs = 0;
> +
>   lua_State *co = thvalue(base-1);
>   /* Check for proper usage. Merge of lua_resume() and auxresume() checks. 
> */
>   if (co->status != LUA_YIELD) {
> @@ -623,8 +627,8 @@ errdead:
>     }
>   }
>   {
> -    unsigned int ndelta = (char *)L->top - (char *)base;
> -    int nargs = ndelta/sizeof(TValue);  /* Compute nargs. */
> +    /*unsigned int */ndelta = (char *)L->top - (char *)base;
> +    /*int */nargs = ndelta/sizeof(TValue);  /* Compute nargs. */
>     int status;
>     if ((char *)co->stack_last-(char *)co->top <= ndelta) {
>       co->ci->top = (StkId)(((char *)co->top) + ndelta);  /* Ok before 
> grow. */
>
> 2. Replace define LUAI_USER_ALIGNMENT_T with typedef (as C++ does not
> support creating new types inside sizeof()).
>
> diff --git a/gamed/libs/luajit/src/luaconf.h 
> b/gamed/libs/luajit/src/luaconf.h
> index 0d4d338..09cff85 100644
> --- a/gamed/libs/luajit/src/luaconf.h
> +++ b/gamed/libs/luajit/src/luaconf.h
> @@ -615,7 +615,7 @@ union luai_Cast { double l_d; long l_l; };
> ** aligned in 16-byte boundaries, then you should add long double in the
> ** union.) Probably you do not need to change this.
> */
> -#define LUAI_USER_ALIGNMENT_T  union { double u; void *s; long l; }
> +typedef union tagLUAI_USER_ALIGNMENT_T { double u; void *s; long l; }
> LUAI_USER_ALIGNMENT_T;
>
> With these changes applied code LuaJIT compiles successfully as C++ code.
>
> However, compiled LuaJIT crushes on errors (same when embedded in our 
> app):
>
> $ ./luajit
> Lua 5.1.3  Copyright (C) 1994-2008 Lua.org, PUC-Rio
> LuaJIT 1.1.4  Copyright (C) 2005-2008 Mike Pall, http://luajit.org/
> > error("boo")
> terminate called after throwing an instance of 'lua_longjmp*'
> Aborted (core dumped)
>
> Stacktrace:
>
> #0  0xffffe410 in __kernel_vsyscall ()
> #1  0xb7c4c875 in raise () from /lib/tls/i686/cmov/libc.so.6
> #2  0xb7c4e201 in abort () from /lib/tls/i686/cmov/libc.so.6
> #3  0xb7e576e0 in __gnu_cxx::__verbose_terminate_handler () from
> /usr/lib/libstdc++.so.6
> #4  0xb7e54f65 in ?? () from /usr/lib/libstdc++.so.6
> #5  0xb7e54fa2 in std::terminate () from /usr/lib/libstdc++.so.6
> #6  0xb7e550ca in __cxa_throw () from /usr/lib/libstdc++.so.6
> #7  0xb7ea7715 in ?? () from ./libtmluajit.so
> #8  0xb7e9af79 in ?? () from ./libtmluajit.so
> #9  0xb7e986e1 in lua_error () from ./libtmluajit.so
> #10 0xb7eab3e8 in ?? () from ./libtmluajit.so
> #11 0xb7bbc12a in ?? ()
> #12 0x0804c010 in ?? ()
> #13 0x08053b98 in ?? ()
> #14 0x08053c48 in ?? ()
> #15 0xb7bbc7b7 in ?? ()
> #16 0x08053b98 in ?? ()
> #17 0x08053c98 in ?? ()
> #18 0x08053bc0 in ?? ()
> #19 0xb7bbc044 in ?? ()
> #20 0x0804c010 in ?? ()
> #21 0xb7ec7ad8 in ?? () from ./libtmluajit.so
> #22 0xbfde9988 in ?? ()
> #23 0xb7eb2beb in ?? () from ./libtmluajit.so
> Backtrace stopped: previous frame identical to this frame (corrupt stack?)
>
> Unfortunately, we currently do not have any resources to debug this
> issue. We also currently have no resources on adopting our existing
> bindings to plain C Lua. So this is a showstopper
>
> Do anyone successfully use LuaJIT compiled as C++ code? Is it possible at 
> all?
>
> We need LuaJIT to work successfully on following platforms:
>
> 1. Production-grade
>   Linux x64 (compiled as 32-bit code). BTW, would it work at all as such?
>
> 2. Development-grade
>   Linux x32
>   Windows x32
>   Intel OS X
>
> Thanks in advance,
> Alexander.