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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/67683] Missed vectorization: shifts of an induction variable
Date: Wed, 23 Sep 2015 08:16:00 -0000 [thread overview]
Message-ID: <bug-67683-4-XCA2vQNqS3@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-67683-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67683
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2015-09-23
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
The issue is the unsupported induction (the PHI) of val
<bb 5>:
# val_16 = PHI <52719(4), val_11(7)>
# i_17 = PHI <0(4), i_12(7)>
_6 = (sizetype) i_17;
_8 = data_7(D) + _6;
_9 = (unsigned char) val_16;
*_8 = _9;
val_11 = val_16 >> 1;
i_12 = i_17 + 1;
if (max_5(D) > i_12)
SCEV already fails to analyze the evolution of val_16 so it doesn't appear
as "induction" to the vectorizer. Reductions with shifts are not handled
either (but reduction uses inside the loop are not supported by the vectorizer
anyway).
next prev parent reply other threads:[~2015-09-23 8:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-22 17:21 [Bug tree-optimization/67683] New: " alalaw01 at gcc dot gnu.org
2015-09-23 8:16 ` rguenth at gcc dot gnu.org [this message]
2015-10-06 15:15 ` [Bug tree-optimization/67683] " alalaw01 at gcc dot gnu.org
2015-10-07 8:05 ` rguenth at gcc dot gnu.org
2024-03-18 7:29 ` pinskia at gcc dot gnu.org
2024-03-18 7:36 ` pinskia at gcc dot gnu.org
2024-03-18 9:16 ` liuhongt at gcc dot gnu.org
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