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Re: [OpenACC 1/11] UNIQUE internal function
- From: Nathan Sidwell <nathan at acm dot org>
- To: Richard Biener <richard dot guenther at gmail dot com>
- Cc: Jakub Jelinek <jakub at redhat dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Bernd Schmidt <bschmidt at redhat dot com>, Jason Merrill <jason at redhat dot com>, "Joseph S. Myers" <joseph at codesourcery dot com>
- Date: Thu, 22 Oct 2015 10:30:52 -0400
- Subject: Re: [OpenACC 1/11] UNIQUE internal function
- Authentication-results: sourceware.org; auth=none
- References: <5627DD78 dot 9040302 at acm dot org> <5627E0DF dot 9050507 at acm dot org> <20151022080444 dot GC478 at tucnak dot redhat dot com> <CAFiYyc09Kkx3uGPJWSYkuyRPEMLjY5Uk8r=72jp6L7kj84O9Dw at mail dot gmail dot com> <5628EC53 dot 9090006 at acm dot org> <CAFiYyc3f1zdjZo7WyMHPXZkxNYbfVXa+2N8wMuB4fxKxtEiwDA at mail dot gmail dot com>
On 10/22/15 10:26, Richard Biener wrote:
On Thu, Oct 22, 2015 at 4:01 PM, Nathan Sidwell <nathan@acm.org> wrote:
RETURNS_TWICE will make the invariant motion stop at UNIQUE (HEAD),
but it would have done that anyway. It will also be a CSE barrier, thus
tem = global;
UNIQUE(HEAD)
tem2 = global;
will not CSE tem2 to tem.
Yes, I can see it would behave like that for something globally visible. What
about state that isn't so visible? (perhaps I'm worrying about something that
doesn't matter, but I'd like to understand)
nathan