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* Thomas Harning, Jr.:

> On Fri, Mar 6, 2009 at 7:02 AM, Luiz Henrique de Figueiredo
> <> wrote:
>>> Lua uses doubles on 32bit machines, shouldn't 64bit machines use long
>>> doubles or even quadruple precision floats ?
>> Do 64-bit machines suppport long doubles in hardware?
> The x86_64 architecture does not support long doubles in hardware.

But not with SSE2, you have to fallback to x87 FP, which results in a
performance hit.

What's worse, sizeof(long double) is 16 for alignment reasons, which
pushes the conceptual word size to 32 bytes.