Re: [PATCH] lib/raid6: Add AVX2 optimized recovery functions

[Andi Kleen]

> The code is compiled so that the xmm/ymm registers are not available to
> the compiler.  Do you have any known examples of asm volatiles being
> reordered *with respect to each other*?  My understandings of gcc is
> that volatile operations are ordered with respect to each other (not
> necessarily with respect to non-volatile operations, though.)

Can you quote it from the manual? As I understand volatile as usual
is not clearly defined. 

gcc has a lot of optimization passes and volatile bugs are common.


> Either way, this implementatin technique was used for the MMX/SSE
> implementations without any problems for 9 years now.

It's still wrong.

Lying to the compiler usually bites you at some point.

-Andi
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