Bug #78341 [Opn->Asn]: Opcache DFA pass over-optimized?

From: Date: Mon, 29 Jul 2019 10:36:29 +0000
Subject: Bug #78341 [Opn->Asn]: Opcache DFA pass over-optimized?
References: 1  Groups: php.bugs 
Request: Send a blank email to php-bugs+get-221980@lists.php.net to get a copy of this message
Edit report at https://bugs.php.net/bug.php?id=78341&edit=1

 ID:                 78341
 Updated by:         nikic@php.net
 Reported by:        jfcherng at gmail dot com
 Summary:            Opcache DFA pass over-optimized?
-Status:             Open
+Status:             Assigned
 Type:               Bug
 Package:            opcache
 Operating System:   Win7 x64
 PHP Version:        7.3.8RC1
-Assigned To:        
+Assigned To:        nikic
 Block user comment: N
 Private report:     N

 New Comment:

We're generating

#164.CV30($zvalIsRef) [bool] RANGE[0..1] = IS_NOT_IDENTICAL #162.V36 [any] null
JMPZ #164.CV30($zvalIsRef) [bool] RANGE[0..1] BB17

instead of

#164.CV30($zvalIsRef) [bool] RANGE[0..1] = IS_NOT_IDENTICAL #162.V36 [any] null
NOP
JMPZ #164.CV30($zvalIsRef) [bool] RANGE[0..1] BB17


Previous Comments:
------------------------------------------------------------------------
[2019-07-28 12:30:18] jfcherng at gmail dot com

Line 268: https://github.com/symfony/var-dumper/blob/v4.3.3/Cloner/VarCloner.php#L268

"zvalIsRef" is defined in: https://github.com/symfony/var-dumper/blob/v4.3.3/Cloner/VarCloner.php#L84-L89

------------------------------------------------------------------------
[2019-07-28 12:26:33] jfcherng at gmail dot com

Description:
------------
PHP 7.3.8RC1 (and 7.4snapshot) emits notices after I update symfony/var-dumper to v4.3.3 today.

"zvalIsRef in vendor\symfony\var-dumper\Cloner\VarCloner.php on line 268"

The variable "zvalIsRef" around VarCloner.php on line 268 is actually obviously defined.
So I have much confidence this is a PHP engine's problem.

After some tests, this seems to be the problematic commit https://github.com/php/php-src/commit/e7a83ec8dff962ea624508f18b9b10f5add030cc
. It's parent 3fa9f9cfae2cedd7b6d26b6487dd156321243ab7 works fine in my test.

I am sorry that I am not able to give a smaller test case.


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

declare(strict_types=1);

// remember to set opcache.enable_cli=1 if this test is done in cli
// composer require symfony/var-dumper:v4.3.3
require __DIR__ . '/vendor/autoload.php';

use Symfony\Component\VarDumper\Cloner\VarCloner;

$myVar = new ArrayObject();
$cloner = new VarCloner();
$data = $cloner->cloneVar($myVar);


Expected result:
----------------
no notice is emitted.

Actual result:
--------------
Notice: Undefined variable: zvalIsRef in vendor\symfony\var-dumper\Cloner\VarCloner.php on line 268

Notice: Undefined variable: zvalIsRef in vendor\symfony\var-dumper\Cloner\VarCloner.php on line 268



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



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Edit this bug report at https://bugs.php.net/bug.php?id=78341&edit=1


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