Re: gcc -mieee-with-inexact on ev67 gives wrong results


Subject: Re: gcc -mieee-with-inexact on ev67 gives wrong results
From: Rich Payne (rdp@talisman.alphalinux.org)
Date: Thu Apr 19 2001 - 05:40:48 PDT


On Thu, 19 Apr 2001, Craig Small wrote:

> On Thu, Apr 19, 2001 at 11:05:49AM +0100, Major A wrote:
> > I tried to run the following test program on an alpha ev67 (a Nautilus
> > running debian potato with linux-2.2.17, gcc-2.95.2):
>
> Here's my results, it's a AlphaPC 164SX.
>
> csmall@fozzie:~$ gcc -o fptest1 fptest.c
> csmall@fozzie:~$ gcc -mieee-with-inexact -o fptest2 fptest.c
> csmall@fozzie:~$ ./fptest1
> 1 / 3 = 0.333333
> csmall@fozzie:~$ ./fptest2
> 1 / 3 = 0.333333
> csmall@fozzie:~$ uname -a
> Linux fozzie 2.2.19 #2 Mon Apr 16 17:08:37 EST 2001 alpha unknown
> csmall@fozzie:~$ gcc --version
> 2.95.2

Just tried on a UP1100 and UP2000 (both EV67), same results:
[root@firebrand /root]# vi test.c
[root@firebrand /root]# cp test.c test2.c
[root@firebrand /root]# gcc -o test test.c
[root@firebrand /root]# gcc -mieee-with-inexact -o test2 test2.c
[root@firebrand /root]# ./test
1 / 3 = 0.333333
[root@firebrand /root]# ./test2
1 / 3 = 0.333333
[root@firebrand /root]# gcc -v
Reading specs from /usr/lib/gcc-lib/alpha-redhat-linux/2.96/specs
gcc version 2.96 20000731 (Red Hat Linux 7.0)

However on an EV6 running Debian:
richp@emperor:~$ cp test.c test2.c
richp@emperor:~$ gcc -o test test.c
richp@emperor:~$ gcc -mieee-with-inexact -o test2 test2.c
richp@emperor:~$ ./test
1 / 3 = 0.333333
richp@emperor:~$ ./test2
1 / 3 = 0.25

richp@emperor:~$ gcc -v
Reading specs from /usr/lib/gcc-lib/alpha-linux/2.95.2/specs
gcc version 2.95.2 20000220 (Debian GNU/Linux)
 
> > Currently, I have no access to any other ev67. All other alphas I have
> > access to (ev4, ev45, ev56) give correct results.
> Still learning about alphas, but I think I have a ev56

SX is a pca56, basically an ev56 with less cache and the addition of the
MVI instructions.

--rdp

-- 
Rich Payne
rpayne@alphalinux.org			www.alphalinux.org

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