[PATCH 0/5] some combine patches

[Oleg Endo]

On 16 Nov 2014, at 22:18, Segher Boessenkool <segher@kernel.crashing.org> wrote:

> On Sun, Nov 16, 2014 at 05:45:06PM +0900, Oleg Endo wrote:
>> When you commit those, could you please also add PR 59278 to the ChangeLog so
>> that the commit appears in bugzilla?  After your patches are in, I'd like to
>> add some SH specific test cases (assuming that your patches fix PR 59278).
> 
> It doesn't fix this testcase.  

Too bad.

> Here, recog_for_combine needs to add a
> clobber of T, but it thinks T is not dead.  It doesn't say anything
> about that in the debug dump :-(
> 
> Maybe the movrt_negc pattern shouldn't set T at all, just clobber it?

On SH, it's not just that particular pattern, but a couple of others, which would need to be changed from set-set to set-clobber before/during combine and then converted/split into the actual set-set patterns after combine.  E.g. some patterns set the T bit to a known zero/one value which can be good to know later on.

> Or reg_dead_at_p can be taught about "unused" notes.

Sounds the easier way from my point of view.  I don't know about side effects for other targets of "unused" reg notes are treated as "dead" reg notes.

Cheers,
Oleg