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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/108540] [13 Regression] Frange miscompilation
 of ruby since r13-3261
Date: Thu, 26 Jan 2023 12:37:42 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108540

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
--- gcc/range-op-float.cc.jj    2023-01-16 09:39:36.191929750 +0100
+++ gcc/range-op-float.cc       2023-01-26 13:33:48.712018907 +0100
@@ -607,6 +607,10 @@ foperator_equal::fold_range (irange &r,
     {
       if (op1 =3D=3D op2)
        r =3D range_true (type);
+      // If one operand is -0.0 and other 0.0, they are still equal.
+      else if (real_iszero (&op1.lower_bound ())
+              && real_iszero (&op2.lower_bound ()))
+       r =3D range_true (type);
       else
        r =3D range_false (type);
     }
@@ -617,7 +621,18 @@ foperator_equal::fold_range (irange &r,
       frange tmp =3D op1;
       tmp.intersect (op2);
       if (tmp.undefined_p ())
-       r =3D range_false (type);
+       {
+         // If one range is [whatever, -0.0] and another
+         // [0.0, whatever2], we don't know anything either,
+         // because -0.0 =3D=3D 0.0.
+         if ((real_iszero (&op1.upper_bound ())
+              && real_iszero (&op2.lower_bound ()))
+             || (real_iszero (&op1.lower_bound ())
+                 && real_iszero (&op2.upper_bound ())))
+           r =3D range_true_and_false (type);
+         else
+           r =3D range_false (type);
+       }
       else
        r =3D range_true_and_false (type);
     }
fixes both testcases, but I'm afraid I need to look at other relations too =
with
-0.0 =3D=3D 0.0 in mind.=