In the SSA optimisation framework (part of opcache), we predict and propagate
types of variables.
We also may detect situations when some variables may be undefined.
If variable can't be "undefined", we may avoid unnecessary run-time checks (e.g
.like in ZEND_ADD_LONG handler).
Local variables almost always initialized before usage, but with exiting
behavior, function arguments always may be uninitialized.
$ sapi/cli/php -d opcache.opt_debug_level=0x400000 2>&1 ../Zend/bench.php | less
...
fibo_r: ; (lines=14, args=1, vars=1, tmps=3, ssa_vars=9, no_loops)
...
#1.CV0($n) [undef, any] = RECV 1
#2.T1 [bool] RANGE[0..1] = IS_SMALLER #1.CV0($n) [undef, any] int(2)
JMPZ #2.T1 [bool] RANGE[0..1] BB2
...
With the patch $n won't include "undef" anymore.
Thanks. Dmitry.
________________________________
From: Joe Watkins <[email protected]>
Sent: Wednesday, June 1, 2016 8:42:49 PM
To: Dmitry Stogov
Cc: PHP internals; Nikita Popov
Subject: Re: [PHP-DEV] [RFC] Replace "Missing argument" warning with "Too few
arguments" exception
Evening,
Could you expand on the "obvious optimization opportunities" in the
document ?
They are not obvious to me, and even if they were, this document is part of
the history of this change, so a little more detail would be nice.
Cheers
Joe
On Wed, Jun 1, 2016 at 11:55 AM, Dmitry Stogov
<[email protected]<mailto:[email protected]>> wrote:
hi,
Please take a look into the proposal.
https://wiki.php.net/rfc/too_few_args
The RFC is extremely simple (both proposal and implementation) and almost
completely described by the email subject.
I think, this mini-RFC doesn't need 2-weeks discussion period, so I'm going to
start the vote on next week.
Thanks. Dmitry.
