[cfe-commits] OpenMP-Patch-1: fopenmp option support

[Mahesha HS]

Hi Ron and Hal,

I think, my investigation on -fno-openmp was not thorough enough.
Based on your mails, I do think that Clang should have support for
this option too. I will support this option.


--
mahesha


On Mon, Oct 29, 2012 at 5:33 PM, Hal Finkel <hfinkel at anl.gov> wrote:
> ----- Original Message -----
>> From: "Mahesha HS" <mahesha.llvm at gmail.com>
>> To: "Eli Friedman" <eli.friedman at gmail.com>, "Dmitri Gribenko" <gribozavr at gmail.com>
>> Cc: "llvm cfe" <cfe-commits at cs.uiuc.edu>
>> Sent: Monday, October 29, 2012 12:47:50 AM
>> Subject: [cfe-commits] OpenMP-Patch-1: fopenmp option support
>>
>> Hi Eli and Dmitri,
>>
>> Let me start again from the beginning one step at a time. Going
>> further, I avoid sending more than one patch at a time as reviewing
>> (big) several patches requires considerable effort, and also some
>> time
>> it is confusing. Attached is the very first patch to support -fopenmp
>> option. This patch is in fact smaller one, and it already went
>> through
>> few rounds of review, and all the review comments are taken for it.
>>
>> However, please take one more look at it, and if it is in a good
>> shape
>> to commit, please do the same or provide me an approval to commit
>> this
>> patch. OTOH, if there is any fresh review comments, I will work on
>> it.
>>
>> Note: Chandler as an opinion to support counter part of this option,
>> namely -fno-openmp. I am still thinking, if it is worth supporting it
>> as I am not aware of any other OpenMP compiler supporting such an
>> option. However, let us think about it, and if we decide that it is
>> useful to support it, I will support it.
>
> One thing that we could do, which gcc does not do (as of 4.7.2), is explicitly disable all unused pragma warnings when -fno-openmp is provided. Otherwise, the usefulness of -fno-openmp is certainly context dependent. As Mahesha points out, so long as OpenMP is disabled by default (as it is in gcc and many other compilers), using -fno-openmp by itself is a no-op. The inverted options are sometimes useful for overriding default options in a makefile (at least when the user options appear after the default options in the makefile). In gcc, -fopenmp -fno-openmp leaves OpenMP disabled, while -fno-openmp -fopenmp enables OpenMP.
>
> Mahesha, Thanks again for working on this.
>
>  -Hal
>
>>
>>
>> --
>> mahesha
>>
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>>
>
> --
> Hal Finkel
> Postdoctoral Appointee
> Leadership Computing Facility
> Argonne National Laboratory



-- 
mahesha