Partials v2 gen

[arnaud-lb]

PFAs are created by generating the AST of a Closure at runtime and compiling it. The compiled op_array can be cached similarly to linked classes.

About caching

There are two levels of caching:

• The global opcache (ZCG(hash))
• The caller's run time cache

The cache key in ZCG(hash) is composed of the address of the declaring opline, the address of the function being called, and a prefix.

This scheme is not ideal because:

• The key used in ZCG(hash) may be a valid file name
• This takes a slot in ZCG(hash)
• When opcache is not enabled, only the run time cache is used. This cache stores only one entry, so cache misses will occur when the function being called changes.

A better solution might be to cache PFA op_arrays in the declaring op_array (similarly, the inheritance cache is stored in classes). This cache could store multiple PFAs, and could be used regardless of opcache being enabled.

Alternatively, use a global two-level map: First level is indexed by the "signature" of the PFA, second level by the function being called. This would lead to a better cache hit rate when the same function is partialled in multiple locations.

TODO

• Improve PFA caching when opcache is not enabled, and fix cases that are broken when opcache is not enabled
• Reorganize tests
  • Update RFC-example tests
• PFAs in constant expressions
• bindTo() is a no-op for PFA of closures
• assert(), compact(), extract(), func_get_arg(), get_defined_vars()
• Pre-bound literal optimization

[TimWolla]

Can we get a test case where the function has optional arguments and an incorrect number is given (just to see the error message once).

[arnaud-lb]

This test shows this error message: https://github.com/arnaud-lb/php-src/blob/75dbd22353d81d34d63587f9c703523f5d10b82e/Zend/tests/partial_application/rfc_examples_003.phpt
Do you prefer a dedicated test case?

[TimWolla]

Great, I just realize that the error messages for userland and native functions are already inconsistent with each other:

https://3v4l.org/3G8EO

[TimWolla]

Suggested change

	echo "OK";
	echo $ex::class, ": ", $ex->getMessage(), PHP_EOL;

[TimWolla]

Would it be possible to do this at MINIT, so that it's not necessary to check the (unexpected) path for every call?

[arnaud-lb]

Yes, I agree

[TimWolla]

What's the purpose of this? Wouldn't it work to expose zend_check_type() directly?

[arnaud-lb]

It's not that easy, as the function is always_inline, and uses always_inline functions from this file as well. zend_check_type() is critical, I didn't want to take the risk of performance regression.

So we have the following options:

• Move the function and a bunch of functions it uses to a header file (zend_check_type, zend_check_type_slow, zend_check_intersection_type_from_list, probably others), so we don't lose inline-ability
• Make the function extern inline, but we don't do that (there was a thread about that in a PR).
• Export a wrapper, like I did here

I will think about about the other options