Hi,
Following my last post on bytecode optimization
(http://news.php.net/php.internals/32113), I would like to discuss a few
more things.
The patch in that e-mail allowed the engine itself to do transformations
like, e.g.:
$a = 1*2*3*4*5+1-0; --> $a = 121;
However the patch is now a bit dead because Stas would like to have more
advanced things that I didn't have time yet to look at (because the proposal
introduces several difficult ambiguities in the grammar).
So, let's move on for now :P
My proposal is the following:
some functions when fed with constant arguments always return a constant
value, too. e.g.:
strlen('abcd') === 4.
This means that an optimizer can and should do this transformation. (and
others like: $a='abcd'; strlen($a); -> 4). I think Ilia created a list of
such functions in his optimizer. But I would like to have that list in the
core, so that everybody can benefit from it.
Basically the only thing needed to do is to change PHP_FE() to
PHP_CONST_FE() in the function entry tables.
The patch: http://web.ist.utl.pt/nuno.lopes/zend_const_function_entry.txt
(includes a few function entries changed as an example)
Nuno
P.S.: the university semester has already started, so don't worry with the
e-mail traffic I'm generating because it'll end pretty soon (until the next
vacations :P)
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