rfc:restrict_globals_usage
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| Both sides previous revisionPrevious revisionNext revision | Previous revision |
| rfc:restrict_globals_usage [2020/12/04 11:09] – nikic | rfc:restrict_globals_usage [2021/01/06 11:47] (current) – nikic |
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| * Date: 2020-12-02 | * Date: 2020-12-02 |
| * Author: Nikita Popov <nikic@php.net> | * Author: Nikita Popov <nikic@php.net> |
| * Status: Under Discussion | * Status: Implemented |
| * Target Version: PHP 8.1 | * Target Version: PHP 8.1 |
| * Implementation: https://github.com/php/php-src/pull/6487 | * Implementation: https://github.com/php/php-src/pull/6487 |
| </PHP> | </PHP> |
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| The variable ''$a'' is stored inside a compiled-variable (CV) call frame slot on the virtual machine stack, which allows it to be accessed efficient. In order to allow modification of the variable through ''$GLOBALS'', the ''$GLOBALS'' array stores array elements of type ''INDIRECT'', which contain a pointer to the CV slot. | The variable ''$a'' is stored inside a compiled-variable (CV) call frame slot on the virtual machine stack, which allows it to be accessed efficiently. In order to allow modification of the variable through ''$GLOBALS'', the ''$GLOBALS'' array stores array elements of type ''INDIRECT'', which contain a pointer to the CV slot. |
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| As such, array operations on ''$GLOBALS'' need to check whether the accessed element is ''INDIRECT'' and perform a de-indirection operation. However, as //any// array could potentially be the ''$GLOBALS'' array, this check has to be performed for essentially all array operations on all arrays. This imposes an implementation and performance cost to account for a rarely used edge-case. | As such, array operations on ''$GLOBALS'' need to check whether the accessed element is ''INDIRECT'' and perform a de-indirection operation. However, as //any// array could potentially be the ''$GLOBALS'' array, this check has to be performed for essentially all array operations on all arrays. This imposes an implementation and performance cost to account for a rarely used edge-case. |
| ===== Vote ===== | ===== Vote ===== |
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| Yes/No. | Yes/No. Voting started 2020-12-23 and closes 2021-01-06. |
| | |
| | <doodle title="Restrict $GLOBALS usage as specified?" auth="nikic" voteType="single" closed="true"> |
| | * Yes |
| | * No |
| | </doodle> |
| |
rfc/restrict_globals_usage.1607080143.txt.gz · Last modified: 2020/12/04 11:09 by nikic