Bug #80404 [Com]: opcache breaks expression evaluation order when cast as int

From: Date: Mon, 23 Nov 2020 11:59:03 +0000
Subject: Bug #80404 [Com]: opcache breaks expression evaluation order when cast as int
References: 1  Groups: php.bugs 
Request: Send a blank email to php-bugs+get-230536@lists.php.net to get a copy of this message 
Edit report at https://bugs.php.net/bug.php?id=80404&edit=1

 ID:                 80404
 Comment by:         contact at shivammathur dot com
 Reported by:        contact at shivammathur dot com
 Summary:            opcache breaks expression evaluation order when cast
                     as int
 Status:             Open
 Type:               Bug
 Package:            JIT
 Operating System:   Tested on Ubuntu 18.04
 PHP Version:        8.0Git-2020-11-23 (Git)
 Block user comment: N
 Private report:     N

 New Comment:

@cmb

Can be reproduced with opcache.jit=off, so I'm not sure if this is JIT related.
Jit Status - https://github.com/shivammathur/test-setup-php/runs/1441867898?check_suite_focus=true#step:5:67
Test - https://github.com/shivammathur/test-setup-php/runs/1441867898?check_suite_focus=true#step:6:33


Previous Comments:
------------------------------------------------------------------------
[2020-11-23 11:53:08] cmb@php.net

This looks like a JIT issue.

------------------------------------------------------------------------
[2020-11-23 10:06:00] contact at shivammathur dot com

Description:
------------
PHP 8.0.0-dev (cli) (built: Nov 23 2020 00:27:07) ( NTS )
Copyright (c) The PHP Group
Zend Engine v4.0.0-dev, Copyright (c) Zend Technologies
    with Zend OPcache v8.0.0-dev, Copyright (c), by Zend Technologies

Build Configuration: https://github.com/shivammathur/php-builder/blob/master/.github/scripts/8.0

Script: https://3v4l.org/kkRIE
  curl -o test.php -H Accept:text/plain -sL https://3v4l.org/kkRIE
  for ((i=1;i<=5;i++)); 
  do 
     echo $i
     php test.php
     sleep 1
  done

Above snippet will run the script "https://3v4l.org/kkRIE" multiple times and when opcache
kicks in "(int) (63/ 120 * 100)" starts evaluating to 0.

This works fine with opcache disabled on PHP 8.0 and with or without opcache on PHP 7.4

Test workflow - https://github.com/shivammathur/test-setup-php/runs/1441325553?check_suite_focus=true#step:6:33



Test script:
---------------
<?php

$firstRowColumns  = 63;

var_dump([
    $firstRowColumns,
    ($firstRowColumns / 120),
    ($firstRowColumns / 120 * 100),
    (int) ($firstRowColumns / 120 * 100),
]);

Expected result:
----------------
(int) (63/ 120 * 100) should evaluate to 52 with opcache enabled on PHP 8.0

Actual result:
--------------
(int) (63/ 120 * 100) evaluates to 0 with opcache enabled on PHP 8.0


------------------------------------------------------------------------



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Edit this bug report at https://bugs.php.net/bug.php?id=80404&edit=1

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