3.6.1 patch nomination: r233312 - Fix rare case where APInt divide algorithm applied un-needed transformation.

[Tom Stellard]

Hi Chandler,

Are these commits OK to merge to the 3.6 branch?

http://llvm.org/viewvc/llvm-project?view=revision&revision=233312
http://llvm.org/viewvc/llvm-project?view=revision&revision=235699

-Tom

On Mon, May 04, 2015 at 06:38:46AM +0000, Paweł Bylica wrote:
> Hi again,
> 
> So the candidates are: r233312 and r235699. Both fixes big number division
> in APInt.
> 
> I can perform the merge if accepted.
> 
> - Paweł Bylica
> 
> On Fri, May 1, 2015 at 3:30 AM Yaron Keren <yaron.keren at gmail.com> wrote:
> 
> > r235699 is Pawel's other fix for APInt division.
> >
> > 2015-05-01 3:46 GMT+03:00 Tom Stellard <tom at stellard.net>:
> >
> >> Hi,
> >>
> >> Which commit is the other fix?
> >>
> >> -Tom
> >>
> >> On Thu, Apr 30, 2015 at 10:13:30PM +0000, Paweł Bylica wrote:
> >> > Hi Tom,
> >> >
> >> > It is a fix. However I found another bug in the algorithm. That had been
> >> > fixed also. I think it is good idea to merge both fixes or nothing. I
> >> don't
> >> > have any preferences.
> >> >
> >> > Paweł
> >> >
> >> >
> >> > On Thu, Apr 30, 2015, 23:12 Tom Stellard <tom at stellard.net> wrote:
> >> >
> >> > Ping.
> >> >
> >> > It's hard to tell from the commit message, does this fix a bug, or is
> >> > it an optimization?
> >> >
> >> >
> >> >  Yaron, Chandler, do either of you think this is OK for llvm 3.6?
> >> >
> >> > Thanks,
> >> > Tom
> >> >
> >> > On Fri, Mar 27, 2015 at 01:39:33PM +0000, Paweł Bylica wrote:
> >> > > Hi Chandler, Yaron & Tom,
> >> > >
> >> > > r233312:
> >> > >
> >> > > > Author: yrnkrn
> >> > > > Date: Thu Mar 26 14:45:19 2015
> >> > > > New Revision: 233312
> >> > > >
> >> > > > URL: http://llvm.org/viewvc/llvm-project?rev=233312&view=rev
> >> > > > Log:
> >> > > > Fix rare case where APInt divide algorithm applied un-needed
> >> > > > transformation.
> >> > > >
> >> > > > APInt uses Knuth's D algorithm for long division. In rare cases the
> >> > > > implementation applied a transformation that was not needed.
> >> > > >
> >> > > > Added unit tests for long division. KnuthDiv() procedure is fully
> >> > covered.
> >> > > > There is a case in APInt::divide() that I believe is never used
> >> (marked
> >> > > > with
> >> > > > a comment) as all users of divide() handle trivial cases earlier.
> >> > > >
> >> > > > Patch by Pawel Bylica!
> >> > > >
> >> > > >   http://reviews.llvm.org/D8448
> >> > > >
> >> > > >
> >> > > > Modified:
> >> > > >     llvm/trunk/lib/Support/APInt.cpp
> >> > > >     llvm/trunk/unittests/ADT/APIntTest.cpp
> >> > > >
> >>
> >
> >