auto-vectorizing

[pkmonkey...@g2.nctu.edu.tw]

Hi,everyone.

I have interest in project:PNACL with auto-vectorizing .

I have  some questions about this project:

1.LLVM has already support auto-vectorizing.

   Why we turn off auto-vectorizing in PNACL?

2.If i want to make PNACL to support auto-vectorizing,

   what should i do first?

Thanks!

[JF Bastien]

Hi,

You would need to teach LLVM which vector sizes are OK to generate. Here's a list of supported types:

https://developer.chrome.com/native-client/reference/pnacl-c-cpp-language-support#portable-simd-vectors

LLVM's vectorizer is customizable enough to do this, but we haven't done this work.

Let us know if you're interested in going forward with this.

JF

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[pkmonkey...@g2.nctu.edu.tw]

Thus,i have to construct a loop vectorizer that follows portable simd vectors 's rule.

             Is it right?

            Thanks! 

JF Bastien於 2015年7月26日星期日 UTC+8上午9時32分12秒寫道：

[JF Bastien]

I don't think so. LLVM's current vectorizer needs to know what it can and can't generate.

[pkmonkey...@g2.nctu.edu.tw]

     1.It means vector sizes must be 128 bits for generating in LLVM vetorizer,is it right?

     2.Can you give me one or two example about vector sizes which is not OK to generate and is OK to generate in LLVM vectorizer?
     Thanks a lot! 

      
JF Bastien於 2015年7月27日星期一 UTC+8上午12時02分36秒寫道：

[JF Bastien]

Hi,

The link I provided earlier has that information and more.

JF