Unnecessary instruction generated by GCC 7.2

[Mason]

On 02/12/2017 00:47, Segher Boessenkool wrote:

> On Thu, Nov 30, 2017 at 06:43:09PM -0700, Jeff Law wrote:
> 
>> On 11/29/2017 03:22 AM, Marc Glisse wrote:
>> 
>>> the extra &15 comes from extending from unsigned char to long
>>> I don't know how easy/hard it is to improve, but I am sure it
>>> is more likely to happen if you file an issue in bugzilla ;-)
>> 
>> Certainly more likely to get addressed if a bug is filed ;-)
>> 
>> This is actually an RTL issue AFAICT.  So it's going to be tougher to
>> fix -- lack of range information and the dataflow is going to make it
>> tough for the combiner to do anything.
> 
> Power has this same problem all over the place.  I'm looking to improve
> it but it is not a simple problem.  GCC 9, perhaps.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83272

Regards.