How many XMM registers are available on an x86 processor supporting SSE?

x86 sse cpu-registers processor
klm123 picture klm123 · Apr 5, 2012 · Viewed 7k times · Source

How to find out the number of XMM registers on a processor which supports SSE?

On Intel X5550, for example.

Answer

Daniel Kamil Kozar picture Daniel Kamil Kozar · Apr 5, 2012

The number of XMM registers is fixed in all the processors that support SSE. If the CPU is in 32-bit mode, you can use 8 registers, from xmm0 to xmm7, while if it's in 64-bit mode, you can address 16 registers, starting at xmm0 up to xmm15. This is thanks to using the REX.W prefix.

Related questions

Header files for x86 SIMD intrinsics

Which header files provide the intrinsics for the different x86 SIMD instruction set extensions (MMX, SSE, AVX, ...)? It seems impossible to find such a list online. Correct me if I'm wrong.

Read More
Why is SSE scalar sqrt(x) slower than rsqrt(x) * x?

I've been profiling some of our core math on an Intel Core Duo, and while looking at various approaches to square root I've noticed something odd: using the SSE scalar operations, it is faster to take a reciprocal square root …

Read More
What is the meaning of "non temporal" memory accesses in x86

This is a somewhat low-level question. In x86 assembly there are two SSE instructions: MOVDQA xmmi, m128 and MOVNTDQA xmmi, m128 The IA-32 Software Developer's Manual says that the NT in MOVNTDQA stands for Non-Temporal, and that otherwise it's the …

Read More