[PATCH] combine: Don't create (set (reg:CC) (compare (reg:CC) (const0)))

[Jeff Law]

On 05/11/2015 03:11 PM, Segher Boessenkool wrote:
> On Mon, May 11, 2015 at 11:23:47AM -0600, Jeff Law wrote:
>>> 	* combine.c (simplify_set): When generating a CC set, if the
>>> 	source already is in the correct mode, do not wrap it in a
>>> 	compare.  Simplify the rest of that code.
>> Seems reasonable.  Might not hurt to do a little testing on a cc0 target
>> though.
>
> I tested on mn10300, cris, and m68k.  On m68k it triggers while
> building libgcc (for 040).  I verified the transform is correct.
Seems reasonable to me.

>
> I don't have a setup to actually bootstrap or regression check
> any cc0 target.  A recurring theme :-(
Understood.  As I mentioned in IRC and in another thread, it may be 
useful to set up an aranym instance for m68k bootstrap testing in the 
compile farm.

For other targets, building foo-elf in a single tree build with 
binutils, newlib and the simulator, then running the gcc testsuite with 
the simulator is often a good alternative.  Probably wise to run through 
this once or twice just to get familiar with it, then pull it out when 
really needed ;)

jeff