Hi Arnaud,
Is the main advantage of the patch - elimination of zval copy
constructor for IS_VAR and IS_CV operands?
Does it improve speed only for VAR/CV array operands?
Will the following script require an extra zval ealloc/efree with the patch?
<?php
function foo($x, $y) {
$x ? $y : "default";
}
foo(false, "something");
?>
For now the patch still looks a bit messing to me. Also, I would
probably prefer to use new opcodes ZEND_QM_ASSIGN_VAR and ZEND_JMP_SET_VAR.
I'll try to think a bit more about it later today.
Thanks. Dmitry.
On 07/08/2011 06:39 PM, Arnaud Le Blanc wrote:
Hi,
Thanks for your answer.
Probably it would be better to support both TMP/VAR result. Or even use
different opcodes.
Yes. I've changed the patch so that it still uses IS_TMP_VAR when both
operands are IS_TMP_VAR or IS_CONST.
I've also added some benchmarks in micro_benchmark.php, and a test.phpt that
tests all combinations of (true|false) ? (const|tmp|var|cv) : (const|tmp|var|
cv) (and also for the ?: operator).
The test found a memory leak in the current trunk in the following code:
true ? $a : $b; the result of $b is marked UNUSED, but not the result of $a.
I've modified zend_do_free() to add a ZEND_FREE op after the whole expression
instead.
Best regards,
Arnaud
Le Friday 8 July 2011 07:51:22, vous avez écrit :
Hi Arnaud,
I haven't test your patch yet, but I got the main idea.
I'll need to carefully analyze it. Probably it would be better to
support both TMP/VAR result. Or even use different opcodes.
Thanks. Dmitry.
On 07/07/2011 10:45 PM, Arnaud Le Blanc wrote:
Hi Dmitry,
The ternary operator always deep-copies its second or third operand, and
it is very slow compared to an if/else when the operand is an array for
example.
I tried to improve this by avoiding copies when possible. I ran the test
suite and seen no problem, but I'm not sure if this is correct or not;
could you please review the attached patch ?
The following script shows the improvements:
$a = range(1, 10000);
for($i = 0; $i< 100000; ++$i) {
$a = true ? $a : $a;
}
Without the patch, this runs in more than a minute. With the patch, this
runs in less than 0.01 second.
I copied most of the code from the ZEND_RETURN handler; I'm not sure why
IS_CONST are copied as well ? (can't we prevent the IS_CONST from being
modified by incrementing its refcount ?)
Best regards,
Arnaud
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