Does dmd have SSE intrinsics?

[Jeremie Pelletier]

#ponce wrote:
>>> In practice it's about an 8X speed difference!
>>>
>>> On AMD K8, it's only 2 vs 5 ops, and on K10 it's 2 vs 3 ops.
>>> On i7, movups on aligned data is the same speed as movaps. It's still 
>>> slower if it's an unaligned access.
>>>
>>> It all depends on how important you think performance on Core2 and 
>>> earlier Intel processors is.
>> I wasn't aware of that, and here I was wondering why my SSE code was 
>> slower than the FPU in certain places on my core2 quad, I now recall 
>> using a lot of movups instructions, thanks for the tip.
> 
> Indeed SSE is known to be overkill when dealing with unaligned data.
> In C++ writing SSE code is so painful you either have to use intrisics, or use libraries like Eigen (a SIMD vectorization library based on expression templates, which can generate SSE, AVX or FPU code). But using such a library is often way too intrusive, and alignement is not in standard C++.
> 
> D does already understand arrays operations like Eigen do, in order to increase cacheability. It would be great if it could statically detect 16-byte aligned data and perform SSE when possible (though there must be many others things to do :) ).

The D memory manager already aligns data on 16 bytes boundaries. The 
only case I can think of right now is when data is in a struct or class:

struct {
	float[4] vec; // aligned!
	int a;
	float[4] vec; // unaligned!
}