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From: "jsm28 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/111770] predicated loads inactive lane values not modelled
Date: Thu, 22 Feb 2024 17:11:51 +0000	[thread overview]
Message-ID: <bug-111770-4-iEH1fOAvLI@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-111770-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111770

--- Comment #6 from Joseph S. Myers <jsm28 at gcc dot gnu.org> ---
X + 0. -> X is invalid for FP with signed zero or signaling NaN, and also gets
the wrong quantum exponent for decimal FP unless the zero has the maximum
possible quantum exponent (which is not what you get from all bits of the
representation zero, which is a zero with the minimum possible quantum
exponent, or from converting integer 0 to DFP, which has quantum exponent 0).

(If you add -0. (with maximum quantum exponent, in the DFP case) instead of
+0., that does produce X for X not a signaling NaN - except in FE_DOWNWARD
mode. Whereas adding +0. is only correct in FE_DOWNWARD mode, since 0. - 0. has
positive sign in all other modes.)

      parent reply	other threads:[~2024-02-22 17:11 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-11 12:38 [Bug tree-optimization/111770] New: " tnfchris at gcc dot gnu.org
2023-10-11 12:58 ` [Bug tree-optimization/111770] " rguenth at gcc dot gnu.org
2024-02-21 17:14 ` acoplan at gcc dot gnu.org
2024-02-22  8:10 ` rguenth at gcc dot gnu.org
2024-02-22 11:10 ` acoplan at gcc dot gnu.org
2024-02-22 13:16 ` rguenth at gcc dot gnu.org
2024-02-22 17:11 ` jsm28 at gcc dot gnu.org [this message]

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