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Re: libm

On Tue, 2006-07-11 at 22:02 +0200, Rudi Chiarito wrote:
> Is there a reason why under 32bit FC5 and 64bit FC3 the library
> references libm, while it doesn't under 64bit FC5? It doesn't look like
> the most predictable behaviour to me. Which of the two is considered
> more proper?

Could this be compiler optimizations? GCC can replace libm calls with
inline assembly. Since x86_64 isn't saddled with i[345]86 compatibility
(3DNow, SSE and SSE2 are guaranteed to be available) it can do a lot
more of these optimizations than a generic i386 build can. Newer GCCs
might not even be bothering to link in libm if it has been able to
replace all calls with inline instructions.

Or maybe fftw itself is switching to x86_64 assembly. It appears recent
versions do have x86_64 assembly optimizations.

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