Re: [gtk-osx-users] Universal ppc/i386 build

[John Ralls <jralls ceridwen us>]

On Jan 24, 2013, at 9:24 AM, Steffen Gutmann <muibase yahoo com> wrote:

> Hi John!
> 
>> But that's not the *real* problem. That problem is that configure writes a 
> 
>> value to G_BYTE_ORDER in $PREFIX/lib/glib-2.0/glibconfig.h, there's only 
>> one, and that's used not only in glib itself (where separate runs of 
>> configure for each architecture will take care of the problem for that 
>> particular build) but in other dependent libraries. Setup_universal_build() 
>> tries to finesse that by building separate trees for each architecture, but I 
>> was never able to get it to work right and gave up. The correct fix would 
>> determine endianess at compile time rather than at configure time.
> 
> 
> I have attached a new diff for glib.  It's basically the same as the previous one but the __POWERPC__ and __i386__ defines have been replaced by __BIG_ENDIAN__ and __LITTLE_ENDIAN__ which seems more appropriate here.
> 
> It's very much okay that these defines are Apple-only.  Note the 3 case if-then-elseif-else statement:
> 
> +#if defined(__BIG_ENDIAN__)
> +    #define G_BYTE_ORDER G_BIG_ENDIAN
> +#elif defined(__LITTLE_ENDIAN__)
> +    #define G_BYTE_ORDER G_LITTLE_ENDIAN
> +#else
> +    #define G_BYTE_ORDER $g_byte_order
> +#endif
>  
> Thus, if neither __BIG_ENDIAN__ not __LITTLE_ENDIAN__ is defined, we fall back to whatever the configure script finds as the endianess.
> 
> With that change the relevant part of the glibconfig.h file turns into:
> 
> ...
> #if defined(__BIG_ENDIAN__)
> #define GINT16_TO_BE(val)((gint16) (val))
> #define GUINT16_TO_BE(val)((guint16) (val))
> #define GINT16_TO_LE(val)((gint16) GUINT16_SWAP_LE_BE (val))
> #define GUINT16_TO_LE(val)(GUINT16_SWAP_LE_BE (val))
> #elif defined(__LITTLE_ENDIAN__)
> #define GINT16_TO_LE(val)((gint16) (val))
> #define GUINT16_TO_LE(val)((guint16) (val))
> #define GINT16_TO_BE(val)((gint16) GUINT16_SWAP_LE_BE (val))
> #define GUINT16_TO_BE(val)(GUINT16_SWAP_LE_BE (val))
> #else
> #define GINT16_TO_LE(val)((gint16) (val))
> #define GUINT16_TO_LE(val)((guint16) (val))
> #define GINT16_TO_BE(val)((gint16) GUINT16_SWAP_LE_BE (val))
> #define GUINT16_TO_BE(val)(GUINT16_SWAP_LE_BE (val))
> #endif
> #if defined(__BIG_ENDIAN__)
> #define GINT32_TO_BE(val)((gint32) (val))
> #define GUINT32_TO_BE(val)((guint32) (val))
> #define GINT32_TO_LE(val)((gint32) GUINT32_SWAP_LE_BE (val))
> #define GUINT32_TO_LE(val)(GUINT32_SWAP_LE_BE (val))
> #elif defined(__LITTLE_ENDIAN__)
> #define GINT32_TO_LE(val)((gint32) (val))
> #define GUINT32_TO_LE(val)((guint32) (val))
> #define GINT32_TO_BE(val)((gint32) GUINT32_SWAP_LE_BE (val))
> #define GUINT32_TO_BE(val)(GUINT32_SWAP_LE_BE (val))
> #else
> #define GINT32_TO_LE(val)((gint32) (val))
> #define GUINT32_TO_LE(val)((guint32) (val))
> #define GINT32_TO_BE(val)((gint32) GUINT32_SWAP_LE_BE (val))
> #define GUINT32_TO_BE(val)(GUINT32_SWAP_LE_BE (val))
> #endif
> #if defined(__BIG_ENDIAN__)
> #define GINT64_TO_BE(val)((gint64) (val))
> #define GUINT64_TO_BE(val)((guint64) (val))
> #define GINT64_TO_LE(val)((gint64) GUINT64_SWAP_LE_BE (val))
> #define GUINT64_TO_LE(val)(GUINT64_SWAP_LE_BE (val))
> #elif defined(__LITTLE_ENDIAN__)
> #define GINT64_TO_LE(val)((gint64) (val))
> #define GUINT64_TO_LE(val)((guint64) (val))
> #define GINT64_TO_BE(val)((gint64) GUINT64_SWAP_LE_BE (val))
> #define GUINT64_TO_BE(val)(GUINT64_SWAP_LE_BE (val))
> #else
> #define GINT64_TO_LE(val)((gint64) (val))
> #define GUINT64_TO_LE(val)((guint64) (val))
> #define GINT64_TO_BE(val)((gint64) GUINT64_SWAP_LE_BE (val))
> #define GUINT64_TO_BE(val)(GUINT64_SWAP_LE_BE (val))
> #endif
> #define GLONG_TO_LE(val)((glong) GINT32_TO_LE (val))
> #define GULONG_TO_LE(val)((gulong) GUINT32_TO_LE (val))
> #define GLONG_TO_BE(val)((glong) GINT32_TO_BE (val))
> #define GULONG_TO_BE(val)((gulong) GUINT32_TO_BE (val))
> #define GINT_TO_LE(val)((gint) GINT32_TO_LE (val))
> #define GUINT_TO_LE(val)((guint) GUINT32_TO_LE (val))
> #define GINT_TO_BE(val)((gint) GINT32_TO_BE (val))
> #define GUINT_TO_BE(val)((guint) GUINT32_TO_BE (val))
> #define GSIZE_TO_LE(val)((gsize) GUINT32_TO_LE (val))
> #define GSSIZE_TO_LE(val)((gssize) GINT32_TO_LE (val))
> #define GSIZE_TO_BE(val)((gsize) GUINT32_TO_BE (val))
> #define GSSIZE_TO_BE(val)((gssize) GINT32_TO_BE (val))
> #if defined(__BIG_ENDIAN__)
>     #define G_BYTE_ORDER G_BIG_ENDIAN
> #elif defined(__LITTLE_ENDIAN__)
>     #define G_BYTE_ORDER G_LITTLE_ENDIAN
> #else
>     #define G_BYTE_ORDER G_LITTLE_ENDIAN
> #endif
> ...
> 
> Isn't that almost exactly what we want?
> 
> Other modules that build on top of glib will then naturally use the right endianess.
> 
> The only other case I found that needs special handling is libffi.  But maybe there are more things to check.  Do you know of any other problems that need specific handling for universal builds?

Ah, I see how it works. Sorry for being dense.

The other universal build problem used to be gtk-update-icon-cache and making sure that it generated the right-endian cache for the architecture. Maybe your GLib fix will handle that.

Are you going to open a Glib bug for this and submit your patch, or are you going to leave that for me? Ditto the libffi pull request?

Regards,
John Ralls