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Re: [Chicken-users] llvm-gcc / clang


From: F. Wittenberger
Subject: Re: [Chicken-users] llvm-gcc / clang
Date: Fri, 03 Dec 2010 21:27:02 +0100

Am Freitag, den 03.12.2010, 03:30 -0500 schrieb Felix:
> From: Thomas Chust <address@hidden>
> Subject: Re: [Chicken-users] llvm-gcc / clang
> Date: Thu, 2 Dec 2010 16:16:21 +0100
> 
> > 2010/12/1 Felix <address@hidden>:
> >> [...]
> >> Oh, and clang gave me stupid warnings that where actually wrong
> >> (an "x == x" comparison of floats to detect NaN, which is IMHO
> >> totally correct, triggers a warning - but I'm sure John can give
> >> us the correct interpretation of the standard C semantics).

Whatever the standard semantics are, a warning in this case is IMHO ok.

Given then warning the compiler could/should produce whatever the
standard requires.

But I can easily see, how a compiler could easer produce better code, if
it knew that NaN == NaN will be the same as 0 == 0.  (E.g., just compare
two registers and not compile code to check vor a special NaN value.)





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