[Openmp-dev] Knowing if an IR instruction will be executed by an OpenMP region

[Cownie, James H]

> is there a way to understand if an LLVM IR instruction will be executed by an OpenMP constructs?

The simple answer is "No", you can't in general tell at compile time whether code will be executed in parallel. (It could be in a separate compilation unit, or even a dynamic library which is only dlopened at runtime).

Even without those practical examples, even knowing whether a given IR instruction will ever be executed is  clearly the same as the halting problem...

-- Jim

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

-----Original Message-----
From: openmp-dev-bounces at cs.uiuc.edu [mailto:openmp-dev-bounces at cs.uiuc.edu] On Behalf Of Simone Atzeni
Sent: Friday, February 6, 2015 6:18 PM
To: openmp-dev at dcs-maillist2.engr.illinois.edu
Subject: [Openmp-dev] Knowing if an IR instruction will be executed by an OpenMP region

HI all,

is there a way to understand if an LLVM IR instruction will be executed by an OpenMP constructs?
If we have an OpenMP region the instructions within it will be placed in an “ompmicrotask” function, however what if I call a function inside the OpenMP pragma? Is there a way to find out the instructions inside that function will be executed in parallel?

Thanks
Best,
Simone


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