Any usable SIMD implementation?

[Marco Leise via Digitalmars-d]

Am Mon, 04 Apr 2016 14:02:03 +0000
schrieb 9il <ilyayaroshenko at gmail.com>:

> Target cpu configuration:
> - CPU architecture (done)
> - Count of FP/Integer registers
> - Allowed sets of instructions: for example, AVX2, FMA4
> - Compiler optimization options (for math)
> 
> Ilya

- On amd64, whether floating-point math is handled by the FPU
  or SSE. When emulating floating-point, e.g. for
  float-to-string and string-to-float code, it is useful to
  know where to get the active rounding mode from, since they
  may differ and at least GCC has a switch to choose between
  both.
- For compile time enabling of SSE4 code, a version define is
  sufficient. Sometimes we want to select a code path at
  runtime. For this to work, GDC and LDC use a conservative
  feature set at compile time (e.g. amd64 with SSE2) and tag
  each SSE4 function with an attribute to temporarily elevate
  the instruction set. (e.g. @attribute("target", "+sse4"))
  If you didn't tag the function like that the compiler would
  error out, because the SSE4 instructions are not supported
  by a minimal amd64 CPU.
  To put this to good use, we need a reliable way - basically
  a global variable - to check for SSE4 (or POPCNT, etc.). What
  we have now does not work across all compilers.

-- 
Marco