Re: [RFC] gcc feature request: Moving blocks into sections

[Steven Rostedt]

On Mon, 2013-08-05 at 22:26 -0400, Jason Baron wrote:

> I think if the 'cold' attribute on the default disabled static_key 
> branch moved the text completely out-of-line, it would satisfy your 
> requirement here?
> 
> If you like this approach, perhaps we can make something like this work 
> within gcc. As its already supported, but doesn't quite go far enough 
> for our purposes.

It may not be too bad to use.

> 
> Also, if we go down this path, it means the 2-byte jump sequence is 
> probably not going to be too useful.

Don't count us out yet :-)


static inline bool arch_static_branch(struct static_key *key)
{
	asm goto("1:"
		[...]
		: : "i" (key) : : l_yes);
	return false;
l_yes:
	goto __l_yes;
__l_yes: __attribute__((cold));
	return false;
}

Or put that logic in the caller of arch_static_branch(). Basically, we
may be able to do a short jump to the place that will do a long jump to
the real work.

I'll have to play with this and see what gcc does with the output.

-- Steve


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/