Bug #79888 [Opn->Ver]: Incorrect execution with JIT enabled
Edit report at https://bugs.php.net/bug.php?id=79888&edit=1
ID: 79888
Updated by: nikic@php.net
Reported by: stefan dot kaeser at diva-e dot com
Summary: Incorrect execution with JIT enabled
-Status: Open
+Status: Verified
Type: Bug
Package: Scripting Engine problem
Operating System: Ubuntu 18.04
PHP Version: 8.0.0alpha2
Block user comment: N
Private report: N
New Comment:
Setting $max = 10000 to reduce runtime, with opcache.jit=1205 I get the incorrect result 5000 and
with tracing JIT I get SIGFPE.
Previous Comments:
------------------------------------------------------------------------
[2020-07-23 09:34:40] stefan dot kaeser at diva-e dot com
Description:
------------
I have a very basic script for getting the ammount of PrimeNumbers by doing cascaded loops.
It's mainly for testing execution times of differen programming languages.
When enabling the JIT options, the final result of the script shows an incorrect result.
Test was with Alpha3 of Php8, but could not choose that version in Dropdown yet.
--------
skaeser@whiplash:~/code/php$ time php7.4 TestPrime.php
Testing Primes until: 250000
Primect: 22044
real 0m56,470s
user 0m56,456s
sys 0m0,009s
skaeser@whiplash:~/code/php$ time php8.0 TestPrime.php
Testing Primes until: 250000
Primect: 22044
real 0m43,745s
user 0m43,733s
sys 0m0,008s
skaeser@whiplash:~/code/php$ time php8.0 -d opcache.enable_cli=1 -d opcache.jit_buffer_size=50000000
-d opcache.jit=1235 TestPrime.php
Testing Primes until: 250000
Primect: 124998
real 0m0,023s
user 0m0,014s
sys 0m0,009s
Test script:
---------------
<?php
$max = 250000;
$cnt = 0;
echo "Testing Primes until: " . $max . "\n";
for ($i = 2; $i <= $max; $i++)
{
if (testPrime($i)) $cnt++;
}
echo "Primect: {$cnt}\n";
function testPrime(int $a): bool
{
if ($a < 2)
{
return false;
}
else if ($a == 2)
{
return true;
}
for ($j = 2; $j < $a; $j++)
{
if (($a % $j) == 0)
{
return false;
}
}
return true;
}
Expected result:
----------------
Testing Primes until: 250000
Primect: 22044
Actual result:
--------------
Only with JIT enabled:
Testing Primes until: 250000
Primect: 124998
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=79888&edit=1
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