Re: RFC - VRP1 default mode

[Jeff Law <jeffreyalaw@gmail.com>]

On 10/26/22 08:24, Andrew MacLeod wrote:
> Figured I would ask what you guys think of making ranger the default 
> for the VRP1 pass now.
>
> With partial equivalences and the other bits I checked in the past few 
> weeks I'm not aware of much that the legacy VRP pass gets that ranger 
> doesn't.  The only exception to that which I am aware of is the trick 
> played with the unreachable edges to set global ranges, but that is 
> done in the DOM passes now anyway... so it just happens slightly later 
> in the optimization cycle. There is one test case that needs 
> adjustment for that which was just checking for a mask in DOM2 
> (gcc.dg/tree-ssa/pr107009.c).   At this point I have not aware of 
> anything that Id be concerned about, and the testsuite seems to run 
> cleanly.
>
> We could change the default now and see if any issues show up, giving 
> us a chance to address them. The code base has been well exercised for 
> a while so risk should be low.  We could also reduce code size by 
> stripping out unneeded code if we so desired.
>
> Or we could leave things as they are for one more cycle.  My 
> preference would be to make the switch now and let it play out. Thoughts?

I'd rather switch now than wait another cycle.  We've got mass rebuilds 
coming  up in a few months which should give us a good indicator if 
there's any notable issues that need to get resolved.


Jeff