From: Aldy Hernandez <aldyh@redhat.com>
To: GCC patches <gcc-patches@gcc.gnu.org>
Cc: Andrew MacLeod <amacleod@redhat.com>, Aldy Hernandez <aldyh@redhat.com>
Subject: [COMMITTED] frange: add both zeros to ranges when there's the possiblity of equality.
Date: Wed, 14 Sep 2022 17:08:52 +0200 [thread overview]
Message-ID: <20220914150852.1244397-5-aldyh@redhat.com> (raw)
In-Reply-To: <20220914150852.1244397-1-aldyh@redhat.com>
Every time there's equality at play, we must be careful that any
equality with zero matches both -0.0 and +0.0 when honoring signed
zeros.
We were doing this correctly for the == and != op1_range operators
(albeit inefficiently), but aren't doing it at all when building >=
and <=. This fixes the oversight.
There is change in functionality here for the build_* functions.
This is the last "simple" patch I submit before overhauling NAN and
sign tracking. And that will likely be after Cauldron because it will need
further testing (lapack, ppc64le, -ffinite-math-only, etc).
Regstrapped on x86-64 Linux, plus I ran selftests for
-ffinite-math-only.
gcc/ChangeLog:
* range-op-float.cc (frange_add_zeros): New.
(build_le): Call frange_add_zeros.
(build_ge): Same.
(foperator_equal::op1_range): Same.
(foperator_not_equal::op1_range): Same.
---
gcc/range-op-float.cc | 31 +++++++++++++++++++++++++------
1 file changed, 25 insertions(+), 6 deletions(-)
diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc
index 8f3e5241313..fbc14a730ad 100644
--- a/gcc/range-op-float.cc
+++ b/gcc/range-op-float.cc
@@ -208,6 +208,19 @@ frange_drop_ninf (frange &r, tree type)
r.intersect (tmp);
}
+// If zero is in R, make sure both -0.0 and +0.0 are in the range.
+
+static inline void
+frange_add_zeros (frange &r, tree type)
+{
+ if (r.undefined_p () || r.known_nan ())
+ return;
+
+ if (HONOR_SIGNED_ZEROS (type)
+ && (real_iszero (&r.lower_bound ()) || real_iszero (&r.upper_bound ())))
+ r.set_signbit (fp_prop::VARYING);
+}
+
// Build a range that is <= VAL and store it in R.
static bool
@@ -219,6 +232,10 @@ build_le (frange &r, tree type, const frange &val)
return false;
}
r.set (type, dconstninf, val.upper_bound ());
+
+ // Add both zeros if there's the possibility of zero equality.
+ frange_add_zeros (r, type);
+
return true;
}
@@ -257,6 +274,10 @@ build_ge (frange &r, tree type, const frange &val)
return false;
}
r.set (type, val.lower_bound (), dconstinf);
+
+ // Add both zeros if there's the possibility of zero equality.
+ frange_add_zeros (r, type);
+
return true;
}
@@ -376,9 +397,8 @@ foperator_equal::op1_range (frange &r, tree type,
case BRS_TRUE:
// If it's true, the result is the same as OP2.
r = op2;
- // Make sure we don't copy the sign bit if we may have a zero.
- if (HONOR_SIGNED_ZEROS (type) && r.contains_p (build_zero_cst (type)))
- r.set_signbit (fp_prop::VARYING);
+ // Add both zeros if there's the possibility of zero equality.
+ frange_add_zeros (r, type);
// The TRUE side of op1 == op2 implies op1 is !NAN.
r.clear_nan ();
break;
@@ -480,9 +500,8 @@ foperator_not_equal::op1_range (frange &r, tree type,
case BRS_FALSE:
// If it's false, the result is the same as OP2.
r = op2;
- // Make sure we don't copy the sign bit if we may have a zero.
- if (HONOR_SIGNED_ZEROS (type) && r.contains_p (build_zero_cst (type)))
- r.set_signbit (fp_prop::VARYING);
+ // Add both zeros if there's the possibility of zero equality.
+ frange_add_zeros (r, type);
// The FALSE side of op1 != op2 implies op1 is !NAN.
r.clear_nan ();
break;
--
2.37.1
prev parent reply other threads:[~2022-09-14 15:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-14 15:08 [COMMITTED] Minor fixes to frange Aldy Hernandez
2022-09-14 15:08 ` [COMMITTED] Provide cleaner set_nan(), clear_nan(), and update_nan() methods Aldy Hernandez
2022-09-14 15:08 ` [COMMITTED] Use frange::set_nan() from the generic frange::set() Aldy Hernandez
2022-09-14 15:08 ` [COMMITTED] Pass full range to build_* in range-op-float.cc Aldy Hernandez
2022-09-14 15:08 ` Aldy Hernandez [this message]
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