llvm dev - Nov 2012 - [LLVMdev] loop pragmas

On 11/21/2012 12:48 PM, Tobias Grosser wrote:
> On 11/21/2012 06:56 PM, Krzysztof Parzyszek wrote:
>>
>> Yes, that is not hard to accomplish.
>
> Actually, I believe this is _not_ easy. Though, it makes only sense to
> discuss this with a specific annotation in mind.
Agreed.  If there is a dedicated consumer of certain annotations, then 
after it's done, it should remove the annotations.  This is not hard 
when it can run early enough not to have the annotations altered by 
prior transformations.  Now, if there are special annotations for 
several dedicated consumers, or the consumer has to run late, then it 
does become difficult.

What would be nice is if we came up with a design that would allow a 
relatively easy validation of the annotations (something conceptually 
similar to error-detecting codes).  The consumer then would disregard 
and remove the annotations that are no longer valid.

-Krzysztof

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, 
hosted by The Linux Foundation

----- Original Message -----
> From: "Krzysztof Parzyszek" <kparzysz at codeaurora.org>
> To: "Tobias Grosser" <tobias at grosser.es>
> Cc: llvmdev at cs.uiuc.edu
> Sent: Wednesday, November 21, 2012 12:59:48 PM
> Subject: Re: [LLVMdev] loop pragmas
> 
> On 11/21/2012 12:48 PM, Tobias Grosser wrote:
> > On 11/21/2012 06:56 PM, Krzysztof Parzyszek wrote:
> >>
> >> Yes, that is not hard to accomplish.
> >
> > Actually, I believe this is _not_ easy. Though, it makes only sense
> > to
> > discuss this with a specific annotation in mind.
> 
> Agreed.  If there is a dedicated consumer of certain annotations,
> then
> after it's done, it should remove the annotations.  This is not hard
> when it can run early enough not to have the annotations altered by
> prior transformations.  Now, if there are special annotations for
> several dedicated consumers, or the consumer has to run late, then it
> does become difficult.
> 
> What would be nice is if we came up with a design that would allow a
> relatively easy validation of the annotations (something conceptually
> similar to error-detecting codes).  The consumer then would disregard
> and remove the annotations that are no longer valid.
I proposed something which has this property for OpenMP handling a few months
ago. If any of it were dropped, or things became otherwise inconsistent, because
of the cross-referencing, it would be possible to detect the problem and drop
the entire parallel region. The problem with using this for OpenMP is that there
are cases where dropping the entire parallel region is not a valid thing to do.

 -Hal
> 
> -Krzysztof
> 
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
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-- 
Hal Finkel
Postdoctoral Appointee
Leadership Computing Facility
Argonne National Laboratory

On 11/21/2012 9:05 PM, Hal Finkel wrote:
>
> I proposed something which has this property for OpenMP handling a few
months ago. If any of it were dropped, or things became otherwise inconsistent,
because of the cross-referencing, it would be possible to detect the problem and
drop the entire parallel region. The problem with using this for OpenMP is that
there are cases where dropping the entire parallel region is not a valid thing
to do.
In another compiler that I know, the OpenMP directives were processed 
very early, before any other transformation that could have damaged them.

-Krzysztof

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, 
hosted by The Linux Foundation