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Date: Fri, 25 Apr 2008 08:50:35 -0500
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Subject: [PATCH] More array filling optimizations
From: php_lists@realplain.com ("Matt Wilmas")

Hi all,

Expanding on the idea of passing a size other than 0 to zend_hash_init(),
when possible, which was done awhile ago in a few areas (to save
resize/rehash operations), I finally added an "array_init_size()" that can
be used instead of array_init(), likewise, when a size is known.  As an
example to start, I updated these functions:

array_*: change_key_case, chunk, combine, fill, fill_keys, flip, keys
(without $search_value), map, rand, reverse, slice, splice, unique (since it
copies all entries first), values; and also compact; func_get_args;
get_defined_vars; str_split; and a couple internal uses.

Those were the simplest, most obvious cases I found. :-)  I didn't test
every function, but for example, the array functions that don't do much work
I found to be ~10% faster (with more than 8 elements, otherwise no resizing
would be needed).  If these changes are applied, more can be done where
possible, by others, or I can and send further patches, or update them
myself if I have CVS access...

http://realplain.com/php/array_init_size.diff
http://realplain.com/php/array_init_size_5_3.diff

I was playing with initializing scripts' array( ... ) constructs with the
correct size too, but wasn't sure about the changes or what the opinion
would be.  Runtime creation is improved with >8 elements, though it adds a
bit of compile overhead.  Anyway, separate patches for that:

http://realplain.com/php/array_init_size_vm.diff
http://realplain.com/php/array_init_size_vm_5_3.diff


Thanks,
Matt