#41328 [Opn->Fbk]: Weird results from floor after compiling with pentium4 optimizations
| From: | tony2001@php.net | Date: | Tue, 08 May 2007 17:44:47 +0000 |
| Subject: | #41328 [Opn->Fbk]: Weird results from floor after compiling with pentium4 optimizations | ||
| References: | 1 | Groups: | php.bugs |
| Request: | Send a blank email to php-bugs+get-112410@lists.php.net to get a copy of this message | ||
ID: 41328
Updated by: tony2001@php.net
Reported By: rgonzalez at gnt dot cc
-Status: Open
+Status: Feedback
Bug Type: *Math Functions
Operating System: Linux Slackware 10.2
PHP Version: 5.2.2
New Comment:
Try newer GCC first.
Previous Comments:
------------------------------------------------------------------------
[2007-05-08 17:26:11] rgonzalez at gnt dot cc
Description:
------------
I compiled PHP 5.2.2 with CFLAGS="-O2 -march=pentium4
-mcpu=pentium4", as usual (I've done so with all the 5.x.x series, and
the
proc is a Pentium 4, of course) and a customer complained about weird
results in one of his scripts. I isolated the problem to be related to
the
floor function. The problem was that it returned weird results. Sample
script:
<?php
$nt = 100;
$promrow2['uni_gifts'] = 1;
$promrow2['unidades'] = 10;
$calc_cnt=floor(($nt*$promrow2['uni_gifts'])/$promrow2['unidades']);
print $calc_cnt;
?>
printed :.0000000001
I needed to cast (int)floor to get the right result. I recompiled with
CFLAGS="-O2 -march=i686 -mcpu=i686" and the problem was solved. I've
compiled 5.2.2 with nocona optimizations without problems in other
machines.
Software:
PHP 5.2.2
GCC 3.2.2
Reproduce code:
---------------
<?php
$nt = 100;
$promrow2['uni_gifts'] = 1;
$promrow2['unidades'] = 10;
$calc_cnt=floor(($nt*$promrow2['uni_gifts'])/$promrow2['unidades']);
print $calc_cnt;
?>
Expected result:
----------------
10
Actual result:
--------------
:.0000000001
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=41328&edit=1