math libraries

[Luc Bourhis via Digitalmars-d]

What is the difference between (i) core.math, (ii) std.math, 
(iii) core.stdc.math and (iv) core.stdc.tgmath? (iv) falls back 
on (iii) as far as I can tell. (i) and (ii) seem to emit the same 
old x87 instructions, like fsin e.g., even for double and float. 
What's the difference?

So that leaves only core.stdc.math which may use fast SSE2 scalar 
instructions. It looks like it may do so, from a glance at the 
assembly with GDB. Could somebody shine some light?