[PATCH 1/2, combine] Try REG_EQUAL for nonzero_bits

[Jeff Law]

On 02/10/15 23:42, Thomas Preud'homme wrote:
>> From: Jeff Law [mailto:law@redhat.com]
>> Sent: Wednesday, February 11, 2015 2:04 PM
>>
>> Given the rs6000 is affected, one could do before/after tests natively
>> in the gcc farm to ensure that removing that code doesn't change the
>> generated code across a bootstrap.
>
> Wouldn't that only tell whether the macro can stay undefined for rs6000?
> MD files for rs6000 could have been tighten since then but not others
> backend's MD files.
It's certainly possible, but unlikely.

I would virtually guarantee that lm32, rx, & mep, rx, tilegx, tilegxpro 
  were never updated.

So another approach would be to build some cross tools and verify that 
they generate the same code before/after ripping that code out.

>> That's probably how I'd approach gathering some data about whether or
>> not the comment/code is still appropriate/needed.
>
> Do people with svn access automatically have access to the GCC farm or
> does one needs to request such access?
You have to request access.  IIRC, there's a big ppc64 machine in there.

https://gcc.gnu.org/wiki/CompileFarm

Jeff