Compiling jacobi-1d with Polly

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Khushboo Chitre

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Feb 19, 2022, 1:59:52 AM2/19/22
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Hello,

I’m trying to compile Polybench-c-4.2.1 with the Polly optimizer using the option “-mllvm -polly”. Polly is significantly increasing the execution time of the benchmark "jacobi-1d". The loops in the benchmark are not getting vectorized with Polly, but are getting vectorized without Polly. I tried compiling it with the option “-mllvm -polly -mllvm -polly-vectorizer=polly”. The problem persisted. Am I using the wrong options to compile the benchmark? Suggestions are welcome.


Michael Kruse

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Feb 23, 2022, 4:02:00 AM2/23/22
to Khushboo Chitre, Polly Development
jacobi-1d is a benchmark which could profit from time-tiling which the
upstream Polly does not implement. As such, there are not many
optimization opportunities left. However, it still should vectorize.
"-polly-vectorizer=polly" is not such a good vectorizer and I don't
recommend to use it.

You can print the modified loop using "-mllvm -debug-only=polly-ast"
(requires a build of clang with assertions enabled). Also try
"-Rpass-missed=loop-vectorize", it should give you a hint why it did
not vectorize.

Michael



Am Sa., 19. Feb. 2022 um 00:59 Uhr schrieb Khushboo Chitre
<khus...@iiitd.ac.in>:
>
> Hello,
>
> I’m trying to compile Polybench-c-4.2.1 with the Polly optimizer using the option “-mllvm -polly”. Polly is significantly increasing the execution time of the benchmark "jacobi-1d". The loops in the benchmark are not getting vectorized with Polly, but are getting vectorized without Polly. I tried compiling it with the option “-mllvm -polly -mllvm -polly-vectorizer=polly”. The problem persisted. Am I using the wrong options to compile the benchmark? Suggestions are welcome.
>
>
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Khushboo Chitre

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Mar 1, 2022, 10:34:45 PM3/1/22
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Thank you very much! 
I will try these suggestions.

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