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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libgomp/67986] OpenMP collapse - invalid code generated.
Date: Fri, 16 Oct 2015 13:49:00 -0000	[thread overview]
Message-ID: <bug-67986-4-uHEpRqlLFB@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-67986-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67986

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The wording in the 4.0 and older versions is non-trivial to check at compile
time, sure, there are easy cases that can be detected, but otherwise whether a
value changes is hard to analyze at compile time.  In OpenMP 4.5, there is
additional restriction that the iterators of associated loops can't be even
mentioned in the b, lb and incr expressions, so even j = i * 0 will be invalid,
and then it is something that can be easily detected at compile time.
For OpenMP 5.0, there are vague plans to add support for certain triangular
collapsed loops, but what the exact wording will be is still undecided.


      parent reply	other threads:[~2015-10-16 13:49 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-16 13:13 [Bug libgomp/67986] New: " lbukata at gmail dot com
2015-10-16 13:19 ` [Bug libgomp/67986] " jakub at gcc dot gnu.org
2015-10-16 13:40 ` lbukata at gmail dot com
2015-10-16 13:49 ` jakub at gcc dot gnu.org [this message]

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