I have read at various places that all intel processors before Core 2 Duo (including Core Duo) have 64-bit floating point execution units. (I am not talking about the x87 FPU). Due to this, the sse instructions using 128-bit operands are split into two with 64-bits handled at a time.
Regarding this, I have the following questions:
a. Is this true?
b. Assuming it is true, won't it mean that there is no speed advantage with instructions like addpd as compared to addsd (as the addpd instruction is split into two anyway) ?