On Wed, Aug 29, 2018 at 05:49:02PM +0100, Vlad Lazar wrote:
> On 29/08/18 17:43, Jakub Jelinek wrote:
> > On Wed, Aug 29, 2018 at 05:39:26PM +0100, Vlad Lazar wrote:
> > > r263591 introduced the following regressions on multiple platforms:
> > > +FAIL: c-c++-common/torture/builtin-arith-overflow-17.c -O0 execution
> > > test
> > > +FAIL: c-c++-common/torture/builtin-arith-overflow-17.c -O2 execution
> > > test
> > > +FAIL: c-c++-common/torture/builtin-arith-overflow-17.c -O2 -flto
> > > execution test
> > > +FAIL: c-c++-common/torture/builtin-arith-overflow-17.c -O2 -flto
> > > -flto-partition=none execution test
> > > +FAIL: c-c++-common/torture/builtin-arith-overflow-p-17.c -O0
> > > execution test
> > > +FAIL: c-c++-common/torture/builtin-arith-overflow-p-17.c -O2
> > > execution test
> > > +FAIL: c-c++-common/torture/builtin-arith-overflow-p-17.c -O2 -flto
> > > execution test
> > > +FAIL: c-c++-common/torture/builtin-arith-overflow-p-17.c -O2 -flto
> > > -flto-partition=none execution test
> > >
> > > The cause for this was that in canonicalize_comparison wi::add was used
> > > to add a negative number. This meant
> > > that in case of underflow the flag would not have been set. The solution
> > > is to use wi::sub if the immediate
> > > needs to be decremented.
> > >
> > > The patch fixes the mentioned regressions.
> > > Bootstrapped and regtested on aarch64-none-linux-gnu and
> > > x86_64-pc-linux-gnu.
> >
> > LGTM, but ChangeLog entry is missing, can you please provide one before I
> > can ack it?
> >
> Sorry about that. Here's the ChangeLog:
>
> gcc/
> 2018-08-29 Vlad Lazar <vlad.la...@arm.com>
> * expmed.c (canonicalize_comparison): Enable underflow check.
There should be empty line after the date/name/email line.
For ChangeLog entries of GCC bugzilla PR bugfixes then the next line
should be
PR middle-end/86995
and only then the expmed.c line. "Enable underflow check." doesn't look
sufficiently descriptive to what it does, I'd use
* expmed.c (canonicalize_comparison): Use wi::sub instead of wi::add
if to_add is negative.
Ok for trunk with those changes.
Jakub
