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From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/107608] [13 Regression] Failure on
 fold-overflow-1.c and pr95115.c
Date: Tue, 10 Jan 2023 10:25:02 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107608

--- Comment #16 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
Created attachment 54224
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D54224&action=3Dedit
untested patch

Perhaps this would work.  It solves the testcase, though I think we should
probably audit the operators that don't use the generic
range_operator_float::fold_range to make sure they're not doing anything si=
lly.

Note that we could add similar code whenever we drop to a NAN like const_bi=
nop
does:

      /* Don't constant fold this floating point operation if
         both operands are not NaN but the result is NaN, and
         flag_trapping_math.  Such operations should raise an
         invalid operation exception.  */
      if (flag_trapping_math
          && MODE_HAS_NANS (mode)
          && REAL_VALUE_ISNAN (result)
          && !REAL_VALUE_ISNAN (d1)
          && !REAL_VALUE_ISNAN (d2))
        return NULL_TREE;

I avoided doing so because an frange of NAN does not count as a singleton s=
o it
should never be propagated.  If this is a problem, I could add a similar tw=
eak.

What do y'all think?=