On 07/12/2015 07:56 AM, Segher Boessenkool wrote:
Currently combine tries to make assignments to bitfields (of a register)
whenever it can. If the target has no insv pattern, the result will not
ever match (if the MD is sane at all). Doing insv on registers generates
worse code than what you get if you express things directly (with and/ior),
so many targets do not _want_ to have insv patterns.
This patch changes combine to not generate insv patterns if the target
does not have any.
Bootstrapped and regression checked on powerpc64-linux (with and without
insv patterns there). Also built on many other targets, for many months.
I'm vaguely aware there have been changes to extzv etc. so there now are
extzv<mode>; I'll investigate if that means anything for insv as well.
It's also a new #ifdef HAVE_xxx. But we're not clean there yet so I hope
to get away with that ;-)
Comments? Complaints?
Well, I'd rather avoid the #ifdef. Just because we aren't clean yet
doesn't mean we need to introduce more stuff to clean up later.
It'd also be nice to have a testcase or two. Guessing they'd be target
dependent, but that's OK with me.
jeff
