Re: [PHP-DEV] Of string constants, bytecode, and concatenation

On Wed, Feb 26, 2003 at 05:36:54PM +0100, Derick Rethans wrote:
| No, the engine doesn't do this at compile time. This first one produces:
| 
| number of ops:  5
| line     #  op                   fetch  ext operands
| -------------------------------------------------------------------------------
|    1     0  CONCAT                          ~1, 'foo', 'bar'
|          1  CONCAT                          ~2, ~1, 'baz'
|          2  FETCH_W              local      $0, 's1'
|          3  ASSIGN                          $3, $0, ~2
|    3     4  RETURN                          1
| 
| The second one:
| 
| line     #  op                   fetch  ext operands
| -------------------------------------------------------------------------------
|    1     0  FETCH_W              local      $0, 's2'
|          1  ASSIGN                          $1, $0, 'foobarbaz'
|    2     2  RETURN                          1

Is that output a ZEND_DEBUG thing, or is that an external tool?


| > If not, can anyone explain the barriers to doing something like this?
| 
| It's the job of an optimizer, not of a compiler. And because PHP doesn't 
| have an internal optimizer, this is not optimized out. You can either 

Okay. Makes complete sense. I was thinking more along the lines of
"wouldn't it be nice if...?". I hadn't quite made it to "where would
that belong?". :)

I'll check out the optimizers. I noticed that the new CVS version of APC
seems to have a configuration option for optimization as well, though
I'm not sure how far along it is.


Thanks again,

- Dave
  [email protected]