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x87 is largely deprecated. Try inspecting the code emitted for floating point by all the major compilers.
by uxcn 11y ago
x87 is largely deprecated. Try inspecting the code emitted for floating point by all the major compilers.
- nibnib 11y agoYou are correct. It looks like SSE sqrt matches or beats fsqrt too.
- uxcn 11y agoSSE performance is better than x87, for a number of reasons. Latency and throughput are generally better, but SSE also supports SIMD which allows more than one op per instruction. SSE also has more registers (x87 only has 8 80bit compared to at least 16 128bit). If I'm not mistaken, the number of available execution units with SSE is also larger, which means more opportunities for instruction level parallelism. These are why modern compilers don't emit x87 for floating point.