This is disabled by default yet, but may be enabled compiling zend_execute.c with -DHAVE_GCC_GLOBAL_REGS.
Only tested on Linux x86 and x86_64 with GCC 4.9.2.
Generators all have their own vm_stack, but usually don't go really deep.
In most cases even most of the 4 KB will remain unused (in my tests average is rather 1 KB), but this was tested a straightforward implementation without a lot of abstraction layers.
That way I'm using a more conservative 4 KB stack size which really should be enough for, I think, at least 90% of the cases.
This was necessary to not immediately run out of memory with 95%+ usused vm_stack space: If you have a few thousands of Generators active, your application quickly hits memory_limit with a stack page size of 256 KB...
In addition, it's also a bit faster (70% less instructions for zend_vm_stack_new_page) due to emalloc() not having to allocate a whole new segment (segment size 256 KB). Also no mmap()/malloc() necessary.
Now each HashTable is also zend_array, so it's refcounted and may be a subject for Copy on Write
zend_array_dup() was changed to allocate and return HashTable, instead of taking preallocated HashTable as argument.
Squashed commit of the following:
commit 1e41295097
Author: Dmitry Stogov <dmitry@zend.com>
Date: Sat Jan 31 07:28:58 2015 +0300
Generalize HashTableIterator API to allows its usage without involvement of HashTable.nInternalPonter
commit 5406f21b11
Author: Dmitry Stogov <dmitry@zend.com>
Date: Fri Jan 30 18:08:43 2015 +0300
Reduced alghorithms complexity
commit b37f1d58d2
Author: Dmitry Stogov <dmitry@zend.com>
Date: Fri Jan 30 18:08:30 2015 +0300
Fixed test name
commit fb2d079645
Author: Dmitry Stogov <dmitry@zend.com>
Date: Fri Jan 30 18:08:05 2015 +0300
API cleanup
commit 08302c0d6d
Author: Dmitry Stogov <dmitry@zend.com>
Date: Fri Jan 30 14:20:46 2015 +0300
Make array_splice() to preserve foreach hash position
commit cc4b7be41e
Author: Dmitry Stogov <dmitry@zend.com>
Date: Fri Jan 30 12:24:31 2015 +0300
Make internal function, operation on array passed by reference, to preserve foreach hash position
commit 5aa9712b0a
Author: Dmitry Stogov <dmitry@zend.com>
Date: Fri Jan 30 09:49:35 2015 +0300
Implement consistent behavior for foreach by value over plain object
commit 4c5b385ff5
Author: Dmitry Stogov <dmitry@zend.com>
Date: Fri Jan 30 07:56:37 2015 +0300
More careful iterators update.
commit 721fc9e80d
Author: Dmitry Stogov <dmitry@zend.com>
Date: Thu Jan 29 21:43:28 2015 +0300
Added new test
commit 15a23b1218
Author: Dmitry Stogov <dmitry@zend.com>
Date: Thu Jan 29 21:05:02 2015 +0300
Reimplement iteration magic with HashTableIterators (see https://wiki.php.net/rfc/php7_foreach#implementation_details)
commit 10a3260b1f
Author: Dmitry Stogov <dmitry@zend.com>
Date: Thu Jan 29 21:04:44 2015 +0300
New test
commit eef80c5837
Author: Dmitry Stogov <dmitry@zend.com>
Date: Wed Jan 28 16:52:21 2015 +0300
Fixed foreach by reference iteration over constant array
commit 61e7391873
Author: Dmitry Stogov <dmitry@zend.com>
Date: Wed Jan 28 14:59:54 2015 +0300
Fixed temporary variable re-allocation pass
commit 92e90c09f0
Author: Dmitry Stogov <dmitry@zend.com>
Date: Wed Jan 28 12:44:57 2015 +0300
Fixed operand destruction in case of exceptions in iterator
commit dd2a36a207
Author: Dmitry Stogov <dmitry@zend.com>
Date: Wed Jan 28 10:02:34 2015 +0300
Use GET_OP1_ZVAL_PTR_DEREF() (IS_TMP_VAR and IS_CONST can't be IS_REFERENCE)
commit 4638f7b914
Author: Dmitry Stogov <dmitry@zend.com>
Date: Wed Jan 28 07:43:28 2015 +0300
Change "foreach" statement behavior (this is just a PoC yet)
- "foreach by value" don't relay on internal array/object pointer and doesnt perform array duplication. It just locks it incrementing reference counter. If the original array is modified by some code, the copy on write is performed and "foreach" still work with the old copy.
- it makes no difference if array given to "foreach by value" is reference itself
- "foreach by reference" still use internal array/object pointer and should work similar to PHP-5. (This id not completely implemented)
* 'internal-function-return-types' of github.com:reeze/php-src:
Add load time return type checking to match user land logic
Add test function arguments
Implemented internal function return types
the main idea - the smaller the zend_op structure, the lees memory traffic is required to load VM instructions during execution. The patch reduces the size of each opcode from 48 to 32 bytes (saves 16 bytes for each opcode, and applications use thousands of opoceds). This reduced the number of CPU cache misses by 12% and improved performance of real-life apps by 1-2%.
The patch affects how constants and jump targets are represented in VM during execution. Previously they were implemented as absolute 64-bit pointers. Now they are relative 32-bit offsets.
In run-time constant now should be accessed as:
RT_CONSTANT(op_array, opine->op1) instead of opline->op1.zv
EX_CONSTANT(opline->op1) instead of opline->op1.zv
Jump targets:
OP_JMP_ADDR(opline, opline->op2) instead of opline->op2.jmp_addr
The patch doesn't change zend_op representation for 32-bit systems. They still use absolute addresses. The compile-time representation is also kept the same.
