[Openmp-dev] Proposal: Resolve combined directives in parsing phase

[Cownie, James H via Openmp-dev]

I think we are all in agreement.

Daniel is just pointing out that the compiler should be optimizing the case where the user implied the unneeded barrier (by writing omp parallel {omp for/do {}}), and that if it does that down the line, it’s safe for the front-end to do the omp parallel for => omp parallel { omp for {} } transformation.

-- Jim

Jim Cownie <james.h.cownie at intel.com>
SSG/DPD/TCAR (Technical Computing, Analyzers, and Runtimes)
Tel: +44 117 9071438

From: C Bergström [mailto:cbergstrom at pathscale.com]
Sent: Friday, June 9, 2017 3:39 PM
To: Daniel Schürmann <daniel.schuermann at campus.tu-berlin.de>
Cc: Cownie, James H <james.h.cownie at intel.com>; openmp-dev at lists.llvm.org
Subject: Re: [Openmp-dev] Proposal: Resolve combined directives in parsing phase

James is really clear on the point of "AS-IF" - The compiler can do anything as long as the user can't observe a difference in the behavior. The standard can say add a barrier, but if the compiler can make the code visibly act the same with our without a barrier that's all that matters.

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