Re: [boost] Review Request : Boost.SIMD

Subject: Re: [boost] Review Request : Boost.SIMD
From: Joel FALCOU (joel.falcou_at_[hidden])
Date: 2017-02-10 18:22:38

On 10/02/2017 11:18, TONGARI J via Boost wrote:
> Question: why not provide load/store as member functions (like
> std::atomic)?

I'm fond of having everything int he API as free functions.
If you construct a pack from a pointer, it assuems it's aligned however.

> I just tried some simple examples (e.g. saxpy) with Boost.SIMD but I got a
> bit disappointed since it performs slower than the normal scalar code
> (/arch:AVX2, with BOOST_SIMD_ASSUME_SSE4_2) on VS2015.
> The assembly shows that VC already vectorizes the scalar code, and does
> better than the handwritten SIMD code.

SAXPY is a trivial case where autovectorizer works very well so I'm not 
surprised. I would suggest using some more complex functions (like exp2, 
cosh or w/e) or revise the Boost.SIMD manual code you wrote :) Did you 
used raw loops or loop over one of our range adaptors ?

MSVC is also one compiler we fight hard to get good codegen casue 
sometimes, it is a bit icky :/

Best regards