Re: [COMMITTED] Fold: Fix up merge_truthop_with_opposite_arm for NaNs [PR95351]

[Andrew Pinski <pinskia@gmail.com>]

On Mon, Mar 11, 2024 at 11:41 PM Andrew Pinski (QUIC)
<quic_apinski@quicinc.com> wrote:
>
> > -----Original Message-----
> > From: Andrew Pinski (QUIC) <quic_apinski@quicinc.com>
> > Sent: Sunday, March 10, 2024 7:58 PM
> > To: gcc-patches@gcc.gnu.org
> > Cc: Andrew Pinski (QUIC) <quic_apinski@quicinc.com>
> > Subject: [COMMITTED] Fold: Fix up merge_truthop_with_opposite_arm for
> > NaNs [PR95351]
> >
> > The problem here is that merge_truthop_with_opposite_arm would use the
> > type of the result of the comparison rather than the operands of the
> > comparison to figure out if we are honoring NaNs.
> > This fixes that oversight and now we get the correct results in this case.
> >
> > Committed as obvious after a bootstrap/test on x86_64-linux-gnu.
>
> Committed to the GCC 13 branch too.

And the GCC 12 and 11 branches too.


>
> Thanks,
> Andrew
>
> >
> >       PR middle-end/95351
> >
> > gcc/ChangeLog:
> >
> >       * fold-const.cc (merge_truthop_with_opposite_arm): Use
> >       the type of the operands of the comparison and not the type
> >       of the comparison.
> >
> > gcc/testsuite/ChangeLog:
> >
> >       * gcc.dg/float_opposite_arm-1.c: New test.
> >
> > Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
> > ---
> >  gcc/fold-const.cc                           |  3 ++-
> >  gcc/testsuite/gcc.dg/float_opposite_arm-1.c | 17 +++++++++++++++++
> >  2 files changed, 19 insertions(+), 1 deletion(-)  create mode 100644
> > gcc/testsuite/gcc.dg/float_opposite_arm-1.c
> >
> > diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc index
> > 43105d20be3..299c22bf391 100644
> > --- a/gcc/fold-const.cc
> > +++ b/gcc/fold-const.cc
> > @@ -6420,7 +6420,6 @@ static tree
> >  merge_truthop_with_opposite_arm (location_t loc, tree op, tree cmpop,
> >                                bool rhs_only)
> >  {
> > -  tree type = TREE_TYPE (cmpop);
> >    enum tree_code code = TREE_CODE (cmpop);
> >    enum tree_code truthop_code = TREE_CODE (op);
> >    tree lhs = TREE_OPERAND (op, 0);
> > @@ -6436,6 +6435,8 @@ merge_truthop_with_opposite_arm (location_t
> > loc, tree op, tree cmpop,
> >    if (TREE_CODE_CLASS (code) != tcc_comparison)
> >      return NULL_TREE;
> >
> > +  tree type = TREE_TYPE (TREE_OPERAND (cmpop, 0));
> > +
> >    if (rhs_code == truthop_code)
> >      {
> >        tree newrhs = merge_truthop_with_opposite_arm (loc, rhs, cmpop,
> > rhs_only); diff --git a/gcc/testsuite/gcc.dg/float_opposite_arm-1.c
> > b/gcc/testsuite/gcc.dg/float_opposite_arm-1.c
> > new file mode 100644
> > index 00000000000..d2dbff35066
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/float_opposite_arm-1.c
> > @@ -0,0 +1,17 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O1 -fdump-tree-original -fdump-tree-optimized" } */
> > +/* { dg-add-options ieee } */
> > +/* PR middle-end/95351 */
> > +
> > +int Foo(double possiblyNAN, double b, double c) {
> > +    return (possiblyNAN <= 2.0) || ((possiblyNAN  > 2.0) && (b > c)); }
> > +
> > +/* Make sure we don't remove either >/<=  */
> > +
> > +/* { dg-final { scan-tree-dump "possiblyNAN > 2.0e.0" "original" } } */
> > +/* { dg-final { scan-tree-dump "possiblyNAN_\[0-9\]+.D. > 2.0e.0"
> > +"optimized" } } */
> > +
> > +/* { dg-final { scan-tree-dump "possiblyNAN <= 2.0e.0" "original" } }
> > +*/
> > +/* { dg-final { scan-tree-dump "possiblyNAN_\[0-9\]+.D. <= 2.0e.0"
> > +"optimized" } } */
> > --
> > 2.43.0
>