xunxun <xunxun1982@xxxxxxxxx> writes: >> If you switch to using SSE floating-point, e.g. using "-mfpmath=sse", >> it will still call the library functions even when using -ffast-math >> (because the SSE unit doesn't have special instructions like "fsin" or >> "f2xm1"). I think SSE FP is typically faster than the 387 for many >> CPUs anyway. >> > Well, that's right. > But in my experience, -mfpmath=sse will slow my code very much. Hmm, I've always found SSE FP to be a speedup -- sometimes a _big_ speedup -- over 387 FP, at least when one is using mostly primitive FP operations (mul, divide, sqrt, etc) ... I think it's worth testing, at least. Complicated FP functions like sin, exp, etc, seem to be a little faster on using 387 FP than using SSE FP -- but that's presumably because when using SSE, those functions are implemented in -lm instead of using special instructions. Since you want to switch to a faster FP library _anyway_, the quality of the standard FP library presumably isn't much of a limitation for you... :] > I think -mfpmath=sse option has some bugs on X86. The x86 is really the only place that option is useful, so I hope it's mostly OK there... :] -Miles -- Circus, n. A place where horses, ponies and elephants are permitted to see men, women and children acting the fool.
