Bug #79353 [Opn]: bad optimizing "Null Coalescing Assignment"

From: Date: Mon, 09 Mar 2020 14:34:50 +0000
Subject: Bug #79353 [Opn]: bad optimizing "Null Coalescing Assignment"
References: 1  Groups: php.bugs 
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Edit report at https://bugs.php.net/bug.php?id=79353&edit=1

 ID:                 79353
 Updated by:         nikic@php.net
 Reported by:        bugreports at gmail dot com
 Summary:            bad optimizing "Null Coalescing Assignment"
 Status:             Open
 Type:               Bug
 Package:            opcache
 PHP Version:        7.4Git-2020-03-08 (Git)
-Assigned To:        
+Assigned To:        nikic
 Block user comment: N
 Private report:     N

 New Comment:

I think we mainly need to add pi node placement for coalesce.


Previous Comments:
------------------------------------------------------------------------
[2020-03-08 02:46:53] bugreports at gmail dot com

Description:
------------
with opcache other than "Null coalescing operator" the "Null Coalescing
Assignment" is not completly optimized out

function a()
{
 $test = $test ?? TRUE;
 return $test;
}

function b()
{
 $test ??= TRUE;
 return $test;
}

runtime difference with 50000000 calls:
a(): 3.1884
b(): 3.3666

function name:  a
number of ops:  2
----------------------------------------------------------------------------------
   5     0*       COALESCE                                         ~1      !0
   6     1*       RETURN                                                   <true>

function name:  b
number of ops:  3
----------------------------------------------------------------------------------
  11     0*       COALESCE                                         ~1      !0
         1*       ASSIGN                                           $2      !0, <true>
  12     2*       RETURN                                                   !0



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



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Edit this bug report at https://bugs.php.net/bug.php?id=79353&edit=1

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