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Re: New GCC releases comparison and comparison of GCC4.4 and LLVM2.5 on SPEC2000
On May 13, 2009, at 5:26 AM, Duncan Sands wrote:
-mpc64 sets the x87 floating point control register to not use the
extended precision. This causes some x87 floating point operations
to operate faster and there are no issues with the extra roundings
get when storing an 80bit precision register to a 64bit memory
However, this does break long double, right?
Does LLVM support x87 arithmetic at all or does it default to SSE
arithmetic in 32bits? I guess using SSE math for both would be a
LLVM does support the x86 floating point stack, though it doesn't
all asm expressions for it (which is why llvm-gcc disables math
My understanding is that no effort has been made to produce optimal
when using the x86 fp stack, and all the effort when into SSE instead.
As long as you configure llvm-gcc with --with-arch=pentium-4 or later,
you should be fine. I personally use --with-arch=nocona.