[cairo] Re: Speeding up _cairo_fixed_from_double

[Nicholas Miell]

On Mon, 30 Oct 2006 16:10:31 -0800, Nicholas Miell wrote:

> On Mon, 30 Oct 2006 15:58:12 -0500, Behdad Esfahbod wrote:
> 
>> Cannot reproduce.
>> 
>> This code:
>> 
>> void
>> main (void)
>> {
>>   int endian = 1;
>>   if (*(char *) &endian)
>>     return '\154'; /* 'l' */
>>   else
>>     return '\102'; /* 'B' */
>> }
>> 
> 
> Try "int main(void)" instead of "void main(void)".
> 
> Compiling with -Wall helps, too. :)
> 
> And for little one-off tests like this, you shouldn't use main (on x86,
> anyway -- gcc inserts extra stack alignment ops which confuses the issue).

Sorry to reply to my own mail, but...

This is http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26069

The following does the right thing (on gcc (GCC) 4.1.1 20061011 (Red Hat
4.1.1-30), anyway):
int isBigEndian_union()
{
        union { unsigned u; char c[4]; } x = { .u = 1 };
	return x.c[0];
}

And the moral of the story is that relying on the compiler to do anything
beyond the absolute minimum interpretation of the standard is foolish.

Hope that helps.