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Re: [RFC PATCH, x86_64] Use -mno-sse[,2] to fall back to x87 FP argument passing convention



OTOH, I see no problems having two competing FP subsystems. I'm sure
that for certain problems, one is better than the other. There are
some examples in Bugzilla, where x87 is way faster (for some problems,
as in PR 19780)

To be clear, in the case of PR19780 it is just that SSA and copy propogation makes the variables live in multiple basic blocks, so that the worse global.c register allocator kicks in and does not manage to find a suitable schedule. This has a worse effect on SSE than x87, but that's just bad luck -- nothing particularly related to SSE vs. x87.


Paolo


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