Re: marking mystery code

preston@tera.com (Preston Briggs)
17 Feb 1996 22:51:23 -0500

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From: preston@tera.com (Preston Briggs)
Newsgroups: comp.compilers
Date: 17 Feb 1996 22:51:23 -0500
Organization: Compilers Central
References: 96-02-138 96-02-156 96-02-194
Keywords: GCC, C

>[My recollection was that the code was something like this:
>
> if(a<0) goto A;
> if(a=0) goto B;
> if(a<0) goto C;
> halt; -- cannot happen
>
>and it happened. -John]


I assume you meant


if(a<0) goto A;
if(a=0) goto B;
if(a>0) goto C;
halt; -- cannot happen


If "a" is floating point and a NAN, then the code should fall through
all those tests. Suprising sometimes, but that's the way it is.


Preston Briggs
[The example was fixed point. I think a bug somewhere else caused a jump to
the second test, and a happened to be less than zero. -John]


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