Bug 9190 – Vector operations are not optimized for x86_64 architecture

From what I see in druntime/src/rt/arrayint.d, there are some heavy optimizations for x86 architecture but not for x86_64. For instance, in my code replacing a vector operation which resulted in a call to _arrayExpSliceAddass_k, with a loop, gave me 2x performance boost with -O -release -inline flags (and even more with LDC compiler). As a temporary solution (until optimized versions will be written), I suggest to enhance the following condition by taking target architecture into account: https://github.com/D-Programming-Language/dmd/blob/master/src/arrayop.c#L304

https://github.com/D-Programming-Language/druntime/pull/471 (This was merged quite some time ago)