Messages in this thread | | | Subject | Re: floating-point abuse in 2.1.113 | From | Andi Kleen <> | Date | 06 Aug 1998 02:32:58 +0200 |
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hpa@transmeta.com (H. Peter Anvin) writes:
> Followup to: <199808042250.SAA24173@jupiter.cs.uml.edu> > By author: "Albert D. Cahalan" <acahalan@cs.uml.edu> > In newsgroup: linux.dev.kernel > > > > Yes, of course. You have a literal float multiplied by a literal int. > > The compiler should promote the int and multiply. After that, the compiler > > should convert the result to an int, eliminating the cast. Then the compiler > > should store that int value in the object file. Why not? > > > > If this has anything to do with IEEE rounding modes, gross! > > In that case, gcc needs a -flinux-kernel option. Maybe one of the > > existing flags will make gcc optimize away the floating point math. > > How about -ffast-math? > > > > Very few compilers will do *ANY* arithmetic on floating-point > constants, mostly because it is so incredibly painful to do when > cross-compiling. Since gcc is designed that it can be run as a > cross-compilier if desired...
I don't think this is a big problem anymore with mostly all CPUs supporting standard IEEE floating point arithmetic. Is there any Linux target that has non-IEEE FP? I doubt it.
Gcc combines floating point constants in constant expressions, even when cross compiling.
-Andi
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