4 ms·
There are an equal amount of vector (also used for FP) regs as there are gprs on x86_64 and on Aarch64. Since those registers are rarely used in normal general
by Tuna-Fish 5y ago
There are an equal amount of vector (also used for FP) regs as there are gprs on x86_64 and on Aarch64. Since those registers are rarely used in normal general purpose code, moving some values over there in principle saves register space.
(x87 fp is obsolete and should never be used for anything.)
- KMag 5y agoI'm not sure the latency on moving data between SSE and GP registers on modern x86 processors. If I remember correctly, late 1990s x86 was notoriously slow at moving data between GP registers and the x87 fp stack. I could certainly believe that on some architectures, moving data between vector registers and GP registers is slower than an L1 cache access.