On 6/18/2014 1:05 AM, c0de517e wrote:
On Wednesday, 18 June 2014 at 03:28:48 UTC, Sean Cavanaugh wrote:
I had a nice sad 'ha ha' moment when I realized that msvc can't cope
with restrict on the pointers feeding into the simd intrinsics; you
have to cast it away. So much for that perf :)
http://blogs.msdn.com/b/vcblog/archive/2013/07/12/introducing-vector-calling-convention.aspx
VectorCall is all about working the original x64 ABI that only lets you
officially pass float and double point scalars around in the xmm
registers. vectors require writing a bunch of helper forceinline
functions that always operate on pointers or references, as passing by
value lacked vectorcall, and on x86 pass by value for xmm types won't
even compile.
Ultimately the code ends up with calls to you have to call something
like _mm_store_ps or _mm_stream_ps etc, those are the functions that
take pointers, and you have to cast away volatile (and afaik restrict is
ignored on them as well but you don't to cast it away).
