[Beignet] [PATCH v2 1/2] GBE: continue to refine interfering check.

[Song, Ruiling]

> -----Original Message-----
> From: Beignet [mailto:beignet-bounces at lists.freedesktop.org] On Behalf Of
> Zhigang Gong
> Sent: Monday, September 7, 2015 8:20 AM
> To: beignet at lists.freedesktop.org
> Cc: Gong, Zhigang
> Subject: [Beignet] [PATCH v2 1/2] GBE: continue to refine interfering check.
> 
> More aggresive interfering check, even if both registers are in Livein set or
> Liveout set, they are still possible not interfering to each other.
> 
> v2:
> Liveout interfering check need to take care those BBs which has only one
> register defined.
> 
> For example:
> 
> BBn:
>   ...
>   MOV %r1, %src
>   ...
> 
> Both %r1 and %r2 are in the BBn's liveout set, but %r2 is not defined or used in
> BBn. The previous implementation ignore this BB which is incorrect. As %r1 was
> modified to a different value, it means %r1 could not be replaced with %r2 in
> this case.
I thought of another one: (r0, r1 contain different values)
BB0:
  def r0

BB1:
  def r1
  use r1
  use r0

How could the algorithm deal with it?
And looks like the algorithm is converting the "live-range interference problem" into
"checking the interference in live-In, live-Out set".
Any paper talking on this method?

And for same BB interference (r0, r1 defined and used in same BB), although we don't need to support it yet, I think if we can put an assert, it would be better.

Thanks!
Ruiling