This handles the degenerate case where SCCP replaced the value in the RETURN opcode with a constant, but the VERIFY_RETURN is still there. We can still apply the same optimization, just don't need to adjust the use list in this case. The result is still sub-optimal in that a dead QM_ASSIGN is left behind.
Even if we don't know the exact method being called, include it in the call graph with the is_prototype flag. In particular, we can still make use of return types from prototype methods, as PHP 8 makes LSP violations a hard error. Most other places are adjusted to skip calls with !is_prototype. Maybe some of them would be fine, but ignoring them is conservative.
Even if an explicit return type is given, we might still infer a more narrow one based on return statements. We shouldn't pessimize this just because a type has been declared.
And fix a type in the fetch class flags dumping while here.
RFC: https://wiki.php.net/rfc/enumerations Co-authored-by: Nikita Popov <nikita.ppv@gmail.com> Closes GH-6489.
* PHP-8.0: Fix refcount inference for typed properties
Currently, dynamically declared functions and closures are inserted into the function table under a runtime definition key, and then later possibly renamed. When opcache is not used and a file containing a closure is repeatedly included, this leads to a very large memory leak, as the no longer needed closure declarations will never be freed (https://bugs.php.net/bug.php?id=76982). With this patch, dynamic functions are instead stored in a dynamic_func_defs member on the op_array, which opcodes reference by index. When the parent op_array is destroyed, the dynamic_func_defs it contains are also destroyed (unless they are stilled used elsewhere, e.g. because they have been bound, or are used by a live closure). This resolves the fundamental part of the leak, though doesn't completely fix it yet due to some arena allocations. The main non-obvious change here is to static variable handling: We can't destroy static_variables_ptr in destroy_op_array, as e.g. that would clear the static variables in a dynamic function when the op_array containing it is destroyed. Static variable destruction is separated out for this reason (we already do static variable destruction separately for normal functions, so we only need to handle main scripts). Closes GH-5595.
Some upcoming changes like https://wiki.php.net/rfc/deprecate_null_to_scalar_internal_arg will make it somewhat inconvenient to determine whether a given function invocation will generate a diagnostic. Rather than trying to exclude this in advance, call the function with diagnostics suppressed, and check whether anything was thrown. This adds a new EG flag that is kept specific to the SCCP use-case. This does not use the error_cb hook as it is a (non-TLS) global, and doesn't fully suppress error handling besides. Test this by removing the in advance checks for implode and array_flip.