llvm dev - Jul 2018 - difference between polly stripmine, vector and unroll flags

Hello I m using following polly flags,

clang -O3 -mllvm -polly -mllvm -polly-vectorizer=stripmine
clang -O3 -mllvm -polly -mllvm -polly-vectorizer=polly
clang -O3 -mllvm -polly -mllvm -force-vector-interleave=32

I am getting different execution times for each 3. Can you please tell me
the difference between the optimizations performed by these 3 flags?


Please help
Thank You
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2018-07-16 11:32 GMT-07:00 hameeza ahmed <hahmed2305 at
gmail.com>:
> Hello I m using following polly flags,
>
> clang -O3 -mllvm -polly -mllvm -polly-vectorizer=stripmine
This prepares instructions into vector-sized chunks
(-polly-prevect-width, 4 by default), but does not generate vector
instructions itself. The LoopVectorizer can generate vector
instructions from it.
> clang -O3 -mllvm -polly -mllvm -polly-vectorizer=polly
Like -polly-vectorizer=stripmine, but generates vector instructions itself.
> clang -O3 -mllvm -polly -mllvm -force-vector-interleave=32
This is a LoopVectorizer option. It does not vectorize, but interleave
(a special kind of unrolling).

Michael