public inbox for gcc-cvs@sourceware.org
help / color / mirror / Atom feed
* [gcc r13-3823] [range-op-float] Set NAN possibility for INF + (-INF) and vice versa.
@ 2022-11-09 7:03 Aldy Hernandez
0 siblings, 0 replies; only message in thread
From: Aldy Hernandez @ 2022-11-09 7:03 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:68b0615be2aaff3a8ce91ba7cd0f69ebbd93702c
commit r13-3823-g68b0615be2aaff3a8ce91ba7cd0f69ebbd93702c
Author: Aldy Hernandez <aldyh@redhat.com>
Date: Tue Nov 8 23:42:04 2022 +0100
[range-op-float] Set NAN possibility for INF + (-INF) and vice versa.
Some combinations of operations can yield a NAN even if no operands
have the possiblity of a NAN. For example, [-INF] + [+INF] = NAN and
vice versa.
For [-INF,+INF] + [-INF,+INF], frange_arithmetic will not return a
NAN, and since the operands have no possibility of a NAN, we will
mistakenly assume the result cannot have a NAN. This fixes the
oversight.
gcc/ChangeLog:
* range-op-float.cc (foperator_plus::fold_range): Set NAN for
addition of different signed infinities.
(range_op_float_tests): New test.
Diff:
---
gcc/range-op-float.cc | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc
index 3bc6cc8849d..8282c912fc4 100644
--- a/gcc/range-op-float.cc
+++ b/gcc/range-op-float.cc
@@ -1863,7 +1863,21 @@ foperator_plus::fold_range (frange &r, tree type,
r.set (type, lb, ub);
- if (lb_nan || ub_nan)
+ // Some combinations can yield a NAN even if no operands have the
+ // possibility of a NAN.
+ bool maybe_nan;
+ // [-INF] + [+INF] = NAN
+ if (real_isinf (&op1.lower_bound (), true)
+ && real_isinf (&op2.upper_bound (), false))
+ maybe_nan = true;
+ // [+INF] + [-INF] = NAN
+ else if (real_isinf (&op1.upper_bound (), false)
+ && real_isinf (&op2.lower_bound (), true))
+ maybe_nan = true;
+ else
+ maybe_nan = false;
+
+ if (lb_nan || ub_nan || maybe_nan)
// Keep the default NAN (with a varying sign) set by the setter.
;
else if (!op1.maybe_isnan () && !op2.maybe_isnan ())
@@ -1960,6 +1974,16 @@ range_op_float_tests ()
r1 = frange_float ("-1", "-0");
r1.update_nan (false);
ASSERT_EQ (r, r1);
+
+ // [-INF,+INF] + [-INF,+INF] could be a NAN.
+ range_op_handler plus (PLUS_EXPR, float_type_node);
+ r0.set_varying (float_type_node);
+ r1.set_varying (float_type_node);
+ r0.clear_nan ();
+ r1.clear_nan ();
+ plus.fold_range (r, float_type_node, r0, r1);
+ if (HONOR_NANS (float_type_node))
+ ASSERT_TRUE (r.maybe_isnan ());
}
} // namespace selftest
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2022-11-09 7:03 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-11-09 7:03 [gcc r13-3823] [range-op-float] Set NAN possibility for INF + (-INF) and vice versa Aldy Hernandez
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).