Okay I went through the whole list in detail now. Two functions need to be removed:

• str_getcsv needs to be removed because it uses isspace.
• str_word_count because of the comment here:

  php-src/ext/standard/string.c

  Lines 5571 to 5573 in e0af7c3

  	For the purpose of this function, 'word' is defined as a locale dependent
  	string containing alphabetic characters, which also may contain, but not start
  	with "'" and "-" characters.

I also see you added an XFAIL in one of the tests, I think it's better to not XFAIL the test. Instead, just disable opcache on that test. That way, we can still catch bugs.

Other than the remarks above I think this PR looks good (but someone else should double check).

There are test failures because you forgot the PHP tags in the SKIPIF section.

As a side note, I think that the better solution for the observers is to simply disable SCCP optimisation for those tests and revert the changes done to them, but I will do that during the merge.

I agree.

Merged manually, thanks.