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bug#5754: Bytecomp Arithmetic test failed

From: Andreas Schwab
Subject: bug#5754: Bytecomp Arithmetic test failed
Date: Sun, 04 Apr 2010 10:05:03 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1.95 (gnu/linux)

Chong Yidong <address@hidden> writes:

> The key is that if I compile Emacs with CFLAGS="-g", then
> (funcall
>  (byte-compile
>   (list 'lambda nil
>       (quote (let ((a (expt 2 -1074)) (b 0.125)) (* a 8 b))))))
> returns 0.0.  If I compile Emacs with CFLAGS="-g -O2", then it returns
> 5e-324.
> It looks like this may be a compiler bug.

It's most likely the effect of excess precision, due to floating point
values being held in registers instead of reloaded from memory.  Try


Andreas Schwab, address@hidden
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