Request for code review - (ZEE patch : Redundant Zero extension elimination)

[Ian Lance Taylor]

Paolo Bonzini <bonzini@gnu.org> writes:

> On 08/08/2009 11:59 PM, Sriraman Tallam wrote:
>> Hi,
>>
>>      Here is a patch to eliminate redundant zero-extension instructions
>> on x86_64.
>
> The code looks nice!  However, since it is very specific to x86 (and
> x86 patterns), I'd rather see it in the i386 machine-dependent reorg
> pass.

I don't agree with this.  If we want this code to be x86_64 specific,
then it should be done by having the i386 backend add the pass to the
pass manager, much as plugins can add a pass.  Adding stuff to
md-reorg is a step backward.

In any case it seems to me that this pass should run before regrename
and sched2.

Ian