Hello,
Please consider the following PHP code:
while ( <CONDITION> ) {
<STATEMENT>
}
It currently compiles to something like this for the Zend Engine:
0: <CONDITION>
1: JMPZ -> 4
2: <STATEMENT>
3: JMP -> 0
4: ...
This can easily be rewritten in an equivalent but much more efficient form:
0: JMP -> 2
1: <STATEMENT>
2: <CONDITION>
3: JMPNZ -> 1
The trick is to jump to the conditional expression before the first iteration
and then only having to continue with just on conditional jump on every
subsequent cycle.
This would result in only 1 jump per loop iteration compared to effectively 2
jumps needed per iteration with the current implementation.
It would also make the loop tighter as upon entering the loop (after first
conditional evaluation), one less opcode remains relevant to the loop.
An analogous approach can be taken for the for-loop.
Thanks,
Ben
PS: This is my first post on a PHP mailinglist - I am very excited! :)
--
Benjamin Coutu
Zeyon Technologies Inc.
http://www.zeyos.com
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