[LLVMdev] Failure to optimize vector select

[Matt Arsenault]

On Aug 20, 2013, at 14:49 , Nadav Rotem <nrotem at apple.com> wrote:

> Hi Matt, 
> 
> This code maintains a vector of float4 and it inserts and extracts values from this vector. The ’select’ operations are already vectorized. Maybe a sequence of inst-combines (or DAG-combines) can help. If you re-write this code using scalars then the slp-vectorizer, with some tweaks, will be able to catch it. 
> 

I've tried manually scalarizing the arguments so the other select arguments are scalars, but the vectorizer still doesn't change it. Here is the scalarized IR.

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