ext/intl: Reduce the number of memory allocations (grapheme_levenshtein)

[SakiTakamachi]

No description provided.

[devnexen]

Not sure I m liking this. Not saying it won t get merged eventually though. Is there an issue with the actual code ?

[SakiTakamachi]

@devnexen
No, there's nothing wrong with the code.
I was hoping to improve performance by reducing the number of memory allocations, since more allocations usually mean more overhead.
But on second thought, speed might not be that important in this context...

[devnexen]

cc @youkidearitai if you want to spin your opinion too.
@SakiTakamachi if you fix the segfaults, I ll have a look later today. Cheers.

[nielsdos]

If you want to do this, and I doubt this matters a lot for performance, you can do p1 = safe_emalloc(strlen_2 + 1, sizeof(zend_long) * 2, 0); which is much simpler and doesn't require the 32/64 bit split.

[SakiTakamachi]

@nielsdos
Yeah, I just measured it, and it only showed a 1–2% improvement.
I'm thinking of closing this...

[SakiTakamachi]

@nielsdos

you can do p1 = safe_emalloc(strlen_2 + 1, sizeof(zend_long) * 2, 0); which is much simpler and doesn't require the 32/64 bit split.

In this case, wouldn't the maximum allocatable memory be cut in half on a 32-bit system?

edit: This is just a question out of curiosity.

[nielsdos]

In this case, wouldn't the maximum allocatable memory be cut in half on a 32-bit system?

The total amount of allocated bytes don't change when you do that. If it overflows it wouldn't have fit two allocation either. So how would that change the maximum?

[SakiTakamachi]

@nielsdos
It seems I was overthinking the fact that strlen_2 is signed and ended up drawing the wrong conclusion. You're right.

[SakiTakamachi]

No matter how many times I measure it, the improvement is negligible...
Alright, I'll close this PR. Thanks for reviewing it!

Benchmark 1: /php-dev/sapi/cli/php /mount/intl/1.php
  Time (mean ± σ):     614.4 ms ±   9.8 ms    [User: 601.0 ms, System: 7.2 ms]
  Range (min … max):   605.3 ms … 637.4 ms    10 runs
 
Benchmark 2: /master/sapi/cli/php /mount/intl/1.php
  Time (mean ± σ):     618.0 ms ±  13.8 ms    [User: 605.5 ms, System: 6.3 ms]
  Range (min … max):   605.8 ms … 648.2 ms    10 runs
 
Summary
  '/php-dev/sapi/cli/php /mount/intl/1.php' ran
    1.01 ± 0.03 times faster than '/master/sapi/cli/php /mount/intl/1.php'

[youkidearitai]

@SakiTakamachi If you improve performance this function, I like improve how to use ICU library.