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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/102381] unexpected -Wmaybe-uninitialized
Date: Fri, 17 Sep 2021 04:00:29 +0000 [thread overview]
Message-ID: <bug-102381-4-bX715gCmNp@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-102381-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102381
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-09-17
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
....
[AFTER NORMALIZATION -- [DEF]:
ipp_28 = PHI <ipp_23(17), ipp_11(D)(15)>
is guarded by :
i2.2_26 > 0 (.AND.) i1_10(D) != 0
....
[AFTER NORMALIZATION -- [USE]:
ipp_27 = PHI <ipp_28(21), ipp_23(18)>
is guarded by :
i1_10(D) != 0 (.AND.) (.NOT.) i4_17 < prephitmp_25 (.AND.) _2 == 0
(.OR.)
i1_10(D) != 0 (.AND.) (.NOT.) i4_17 < prephitmp_25 (.AND.) i3.0_1 & 1
...
_2 = i3.0_1 & 1;
So there is a missing simplification
It should have been:
i1_10(D) != 0 (.AND.) (.NOT.) i4_17 < prephitmp_25
prephitmp_25 is defined as:
# prephitmp_25 = PHI <i2.2_26(17), i2.2_21(15)>
So i2.2_26 (as i2.2_21 is the one on the branch which would have been
uninitialized).
So we are down to:
i1_10(D) != 0 (.AND.) (.NOT.) i4_17 < i2.2_26
i4_17 is the loop IV so it should be discarded.
next prev parent reply other threads:[~2021-09-17 4:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-17 1:43 [Bug c/102381] New: " hv at crypt dot org
2021-09-17 4:00 ` pinskia at gcc dot gnu.org [this message]
2021-09-17 4:02 ` [Bug tree-optimization/102381] unexpected -Wmaybe-uninitialized with noreturn inside loop and conditional setting of variable pinskia at gcc dot gnu.org
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