Re: [Patch, vrp] Allow VRP type conversion folding only for widenings upto word mode

[Richard Biener <rguenther@suse.de>]

On Fri, 20 Nov 2015, Jeff Law wrote:

> On 11/20/2015 10:04 AM, Senthil Kumar Selvaraj wrote:
> > On Thu, Nov 19, 2015 at 10:31:41AM -0700, Jeff Law wrote:
> > > On 11/18/2015 11:20 PM, Senthil Kumar Selvaraj wrote:
> > > > On Wed, Nov 18, 2015 at 09:36:21AM +0100, Richard Biener wrote:
> > > > > 
> > > > > Otherwise ok.
> > > > 
> > > > See modified patch below. If you think vrp98.c is unnecessary, feel free
> > > > to dump it :).
> > > > 
> > > > If ok, could you commit it for me please? I don't have commit access.
> > > > 
> > > > Regards
> > > > Senthil
> > > > 
> > > > gcc/ChangeLog
> > > > 2015-11-19  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
> > > > 
> > > > 	* tree.h (desired_pro_or_demotion_p): New function.
> > > > 	* tree-vrp.c (simplify_cond_using_ranges): Call it.
> > > > 
> > > > gcc/testsuite/ChangeLog
> > > > 2015-11-19  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
> > > > 
> > > > 	* gcc.dg/tree-ssa/vrp98.c: New testcase.
> > > > 	* gcc.target/avr/uint8-single-reg.c: New testcase.
> > > I went ahead and committed this as-is.
> > > 
> > > I do think the vrp98 testcase is useful as it verifies that VRP is doing
> > > what we want in a target independent way.  It's a good complement to the
> > > AVR
> > > specific testcase.
> > 
> > I see the same problem on gcc-5-branch as well. Would it be ok to
> > backport the fix to that branch as well?
> That's a call for the release managers.  I typically don't backport anything
> expect ICE or incorrect code generation fixes as I tend to be very
> conservative on what goes onto a release branch.
> 
> Jakub, Richi or Joseph would need to ack into a release branch.

As this is fixes a regression it qualifies in principle.  But as
it is an optimization regression only I'd prefer to wait a bit to look
for fallout.

Richard.

> jeff
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)