Questions about march/mcpu/mattr and good generic defaults
bearophileHUGS at lycos.com
Thu Dec 19 15:55:06 PST 2013
> Do -m32/m64 just mean -march=x86/x86-64?
> To create a generic 32-bit program, are these sane choices:
> -m32 -mcpu=i686 -mattr=sse2 ?
I think sse2 is active on default on Windows.
> I see 100% performance increase between sse2 and sse/none.
> Optimizer seems to like quite a lot.
Right, I think LLVM used to produce SSE code before being able to
produce the older stack-based FP code. So LLVM likes SSE code a
lot. It's the standard.
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