[llvm-dev] Loop vectorizer doesn't try to align vectors on preferred vector alignment

[Benoit Meister via llvm-dev]

Hello,

I'm playing around with vectorization in LLVM 6.0.0, and I noticed that
when creating a vector load out of a scalar load, the  alignment for the
vector load is defined to be the one of the scalar load. For instance,
16-bit vectors get aligned on 2 bytes. This does not correspond to the
preferred alignment for vectors that I specified in the data layout (which
is bigger).

Inspecting lib/Transforms/Vectorize/LoopVectorizer.cpp, there doesn't seem
to be an intent of doing so.
I looked at this method in particular:

void InnerLoopVectorizer::vectorizeMemoryInstruction

Is there a way (that I missed) to make this happen, or would it require a
code change ? Or did I miss anything obvious ?

Thanks in advance,
- Benoit
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