[llvm] r189281 - LoopVectorize: Implement partial loop unrolling when vectorization is not profitable.

[Andrew Trick]

On Aug 28, 2013, at 4:08 PM, Renato Golin <renato.golin at linaro.org> wrote:

> On the other hand, maybe the loop-unrolling pass should be merged into the loop vectorizer...

Yes, targets that want partial unrolling should use the loop vectorizer pass. The analysis the the vectorizer does to determine a profitable unroll factor is applicable even without vector support. Partial unrolling is sort of ILP-level vectorization. Your previous email explained pretty well why it’s all lumped into one pass.

Full unrolling is done for completely different reasons and can run as an early pass.

-Andy
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