On 17/02/12 09:09, Mantis wrote:
17.02.2012 4:30, bearophile пишет:
After seeing this interesting thread:
http://stackoverflow.com/questions/9314534/why-does-changing-0-1f-to-0-slow-down-performance-by-10x
Do you know if there's a simple way to perform _MM_SET_FLUSH_ZERO_MODE
in D?
According to Agner that operation is not needed on Sandy Bridge
processors, but most CPUs around are not that good:
http://www.agner.org/optimize/blog/read.php?i=142
Bye,
bearophile
I could expect this to be adjustable in std.math.FloatingPointControl,
but it isn't.
That's because the x87 doesn't support flush-to-zero, and 32-bit x86
doesn't necessarily have SSE.
But it should probably be added for 64 bit.
Anyway, the assembly code to change FPU control word is
pretty tiny:
http://software.intel.com/en-us/articles/x87-and-sse-floating-point-assists-in-ia-32-flush-to-zero-ftz-and-denormals-are-zero-daz/
