Re: [PATCH][RFC] getting rid of stupid loop in BUG()

[H. Peter Anvin]

Al Viro wrote:
> On Wed, Jul 25, 2007 at 09:56:12AM -0700, Linus Torvalds wrote:
>>
>> On Tue, 24 Jul 2007, David Miller wrote:
>>> From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
>>> Date: Tue, 24 Jul 2007 23:24:55 -0700
>>>
>>>> H. Peter Anvin wrote:
>>>>> How far back was __builtin_trap() supported?
>>>> I think its relatively recent, but it might be within our supported
>>>> compiler window.
>>> I'm pretty sure it is.
>> .. and I'm pretty sure it's immaterial.
>>
>> We don't just do the "ud2" instruction - we also do the file and line 
>> number information after it. Which means that __builtin_trap() is useless.
>>
>> So we might as well keep the loop, since both are two-byte instructions 
>> that tell gcc that it will never continue.
> 
> Umm...  Actually, we might be able to do something like
> {
> 	l: __builtin_trap();
> 	static struct ... v __attribute__((section(...))) = { &&l, n, file };
> }
> 
> except that it would need block-local labels and those are ugly (so's
> &&<label>, while we are at it)...

I thought gcc was buggy when it came to passing &&labels to assembly.

	-hpa
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