GCC still keeps empty loops? (was: [patch 4/21] fix ARCH_HAS_PREFETCH)

[Jamie Lokier]

Linus Torvalds wrote:
> I thought that special case was removed long ago, because it is untenable 
> in C++ etc (where such empty loops happen due to various abstraction 
> issues, and not optimizing them away is just silly).
> 
> But testing shows that you're right at least for 2.95 and 2.96. Argh

Unbelievably, 3.1 doesn't remove empty loops either.
I think there's a case for a compiler flag, `-fremove-empty-loops'.

Empty loop delays aren't portable acrosss compilers in general.  If you
_really_ want an empty loop that must always work with GCC, it's easy
enough to write:

	for (i = 0; i < 100000; i++)
		__asm__ __volatile__ ("");

-- Jamie