1312411 - Add TypedArrayCompare specialization for ints

Status: RESOLVED FIXED

(Core :: JavaScript: Standard Library, defect)

Description

[André Bargull [:anba]]

evilpie suggested this in bug 1293971, comment 3.

And while we're at it, also:
- Add `return 0` to avoid unnecessary swaps in InsertionSort and to ensure the function always returns numbers (https://dxr.mozilla.org/mozilla-central/rev/215f9686117673a2c914ed207bc7da9bb8d741ad/js/src/builtin/TypedArray.js#1100)
- Replace the subtraction with compares, which seems to be faster for doubles (https://dxr.mozilla.org/mozilla-central/rev/215f9686117673a2c914ed207bc7da9bb8d741ad/js/src/builtin/TypedArray.js#1083-1085)

Comment 1

[André Bargull [:anba]]

Attachment: bug1312411.patch

Applies on top of bug 1293971.

Comparisons were faster than subtraction for floating point numbers (tested with random numbers generated with |Math.random() * 1000|). Therefore I've changed TypedArrayCompare to use comparisons. For integer values subtraction was faster, so TypedArrayCompareInt still uses |var diff = x - y|.

Comment 2

[Tom S [:evilpie]]

Comment on attachment 8803949 [details] [diff] [review]
bug1312411.patch

Review of attachment 8803949 [details] [diff] [review]:
-----------------------------------------------------------------

Awesome, thanks for doing this. Do you have some actual performance numbers?

Comment 3

[André Bargull [:anba]]

(In reply to Tom Schuster [:evilpie] from comment #2)
> Awesome, thanks for doing this. Do you have some actual performance numbers?

Time in ms for a single execution of `fn`:
  Int16:   1400 ->  445
  Int32:   1440 ->  460
  Float32: 1160 ->  865
  Float64: 1370 -> 1000

```
function fn() {
    var len = 125;
    var ta = new Float64Array(len);
    var t = 0;
    for (var i = 0; i < 100000; ++i) {
        for (var j = 0; j < len; ++j) ta[j] = Math.random() * 1000;
        var d = dateNow();
        ta.sort();
        t += (dateNow() - d);
    }
    return t;
}

// Run it a few times for optimizations to kick in.
for (var i = 0; i < 10; ++i) print(fn());
```

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/7b9c260074e7
Add integer specialization of TypedArrayCompare. r=evilpie

Comment 5

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/7b9c260074e7