Fix GH-23644: crash on a constant-vs-constant empty array comparison

[lazerg]

When the optimizer proves a variable's value on a branch, it can substitute the constant in and leave a comparison whose two operands are both constants. ZEND_IS_IDENTICAL_EMPTY_ARRAY and ZEND_IS_NOT_IDENTICAL_EMPTY_ARRAY were the only handlers in that group declared without NO_CONST_CONST, unlike the base opcodes and the arithmetic handlers beside them, so the specialiser picked a variant that reads op1 as a variable slot. With a constant index there, the read lands outside the call frame and the process either crashes in zval_undefined_cv() or compares unrelated memory.

Adding the marker to both handlers is the fix ndossche suggested on the issue.

Fixes GH-23644

[ndossche]

You know, if you take someone's patch verbatim and only add OP's test on top of it, then I think it's kinda rude to not give that someone (aka me in this case) credit: only your name is in the NEWS entry...

[lazerg]

You're right, sorry about that. Commit d7abcf0 puts your name on the NEWS entry. The fix is your diff. I only regenerated the VM file and added a test. If you want, I can set you as the commit author too, or close this so you can open your own PR.

[ndossche]

I approve but I'm biased of course