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Re: GCC and Floating-Point (A proposal)
Paul Brook <paul@codesourcery.com> writes:
| On Thursday 26 May 2005 14:25, Scott Robert Ladd wrote:
| > Scott Robert Ladd <scott.ladd@coyotegulch.com> wrote:
| > >>May I be so bold as to suggest that -funsafe-math-optimizations be
| > >>reduced in scope to perform exactly what it's name implies:
| > >>transformations that may slightly alter the meanding of code. Then move
| > >>the use of hardware intrinsics to a new -fhardware-math switch.
| >
| > Richard Guenther wrote:
| > > I think the other options implied by -ffast-math apart from
| > > -funsafe-math-optimizations should (and do?) enable the use of
| > > hardware intrinsics already. It's only that some of the optimzations
| > > guarded by -funsafe-math-optimizations could be applied in general.
| > > A good start may be to enumerate the transformations done on a
| > > Wiki page and list the flags it is guarded with.
| >
| > Unless I've missed something obvious, -funsafe-math-optimizations alone
| > enables most hardware floating-point intrinsics -- on x86_64 and x86, at
| > least --. For example, consider a simple line of code that takes the
| > sine of a constant:
|
| I thought the x86 sin/cos intrinsics were unsafe. ie. they don't
| gave accurate results in all cases.
Indeed.
-- Gaby