On 01/25/2016 11:36 AM, Bob Weinand wrote:
Am 25.01.2016 um 09:13 schrieb Dmitry Stogov <dmi...@zend.com>:
We basically need a way to properly first fetch the args (beware: func_arg
fetches...) before instantiating the call frame, an issue which for example
could be solved if we applied my vm_stack_restructuring patch (because it only
installs call frames after all args were fetched).
I thought about that approach, but the amount of changes doesn't worth the
result. Doing this only for generators doesn't make a lot of sense.
After all, we still have that 2% performance improvement. And the main VM stack
reusage for Generators.
And I believe the proposed layout is also much more close to the C calling
convention and thus more compatible if we ever go the route down to compiling
to assembly.
Ultimately it gives us more flexibility as we also could put point the return
temporary/cv of some opcodes to the right place, ready to call.
We aren't that far yet with the Optimizer, but I think I see it coming, where
we'll benefit more from fixed places. It might be just a few moves less, but
function arg passing is very common in PHP, so the benefit will be more
significant the more optimizations we apply.
Remember that small thing removing ZEND_SEND_VAL_SPEC_TMP_TMP_HANDLERs where
unnecessary? When we'll be able to know which variables may hold references or
which not, we'll suddenly be able to directly write to the function parameter
slot in much more cases.
I still stand by the point that doing it now (which small, but non-negligible
improvement), will bring us a bigger improvement later. Many small improvements
built around this patch will give us a big one in the end.
I put a note about "postponed" idea at https://wiki.php.net/php-7.1-ideas.
May be we will return to this later.
Thanks. Dmitry.
Thanks. Dmitry.
Thanks,
Bob
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