bug-gnu-emacs
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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
-ffloat-store.

Andreas.

-- 
Andreas Schwab, address@hidden
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."






reply via email to

[Prev in Thread] Current Thread [Next in Thread]