There should also be an assert in the new LF constructor, which ensures that
the two
arguments are congruent. Better yet, just supply one argument (the
speciesData),
and derive the MT. These new LFs are pretty confusing, and it's best to nail
down
unused degrees of freedom.
— John
P.S. I would have expected this problem to be solved by having the MHI.toArray
function
return a box object with a single @Stable array field. Did that approach fail?
I.e., this wrapper emulates a frozen array (until that happy day when we have
real
frozen arrays):
class ArrayConstant<T> {
private final @Stable T[] values;
public ArrayConstant(T[] values) {
for (T v : values) Objects.requireNonNull(v);
this.values = values.clone();
}
public T get(int i) { return values[i]; }
//public int length() { return values.length; }
}
The JIT should be able to constant fold through ac.get(i) whenever ac and i are
constants.
On Sep 20, 2016, at 8:17 AM, Vladimir Ivanov <vladimir.x.iva...@oracle.com>
wrote:
>
> Looks good.
>
> src/java.base/share/classes/java/lang/invoke/LambdaFormEditor.java:
> + LambdaForm bmhArrayForm(MethodType type, BoundMethodHandle.SpeciesData
> speciesData) {
> + int size = type.parameterCount();
> + Transform key = Transform.of(Transform.BMH_AS_ARRAY, size);
> + LambdaForm form = getInCache(key);
> + if (form != null) {
> + return form;
> + }
>
> Please, add an assert to ensure the cached LF has the same constraint as
> requested (speciesData).
>
> Best regards,
> Vladimir Ivanov
>
> On 9/20/16 3:53 PM, Michael Haupt wrote:
>> Dear all,
>>
>> please review this change.
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8161211
>> Webrev: http://cr.openjdk.java.net/~mhaupt/8161211/webrev.00/
>>
>> The method handle loop combinators introduced with JEP 274 were originally
>> not intrinsified, leading to poor performance as compared to a pure-Java
>> baseline, but also to handwired method handle combinations. The intrinsics
>> introduced with 8143211 [1] improved on the situation somewhat, but still
>> did not provide good inlining opportunities for the JIT compiler. This
>> change introduces a usage of BoundMethodHandles as arrays to carry the
>> various handles involved in loop execution.
>>
>> Extra credits to Vladimir Ivanov, who suggested the BMH-as-arrays approach
>> in the first place, and Claes Redestad, who suggested to use LambdaForm
>> editing to neatly enable caching. Thanks!
>>
>> Performance improves considerably. The table below reports scores in ns/op.
>> The "unpatched" column contains results from before applying the patch for
>> 8161211; the "patched" column, from thereafter.
>>
>> The create benchmarks measure the cost of loop handle creation. The baseline
>> and baselineMH benchmarks measure the cost of running a pure Java and
>> handwired method handle construct.
>>
>> Relevant comparisons include loop combinator results versus baselines, and
>> versus unpatched loop combinator results. For the latter, there are
>> significant improvements, except for the creation benchmarks (creation has a
>> more complex workflow now). For the former, it can be seen that the
>> BMH-array intrinsics generally perform better than handwired handle
>> constructs, and have moved much closer to.
>>
>> Thanks,
>>
>> Michael
>>
>>
>>
>> [1] https://bugs.openjdk.java.net/browse/JDK-8143211
>>
>>
>>
>> Benchmark (iterations)
>> unpatched patched
>> MethodHandlesCountedLoop.Create.create3 N/A
>> 16039.108 18400.405
>> MethodHandlesCountedLoop.Create.create4 N/A
>> 15621.959 17924.696
>> MethodHandlesCountedLoop.Invoke.baseline3 0 2.858
>> 2.839
>> MethodHandlesCountedLoop.Invoke.baseline3 1 5.125
>> 5.164
>> MethodHandlesCountedLoop.Invoke.baseline3 10 11.887
>> 11.924
>> MethodHandlesCountedLoop.Invoke.baseline3 100 67.441
>> 67.281
>> MethodHandlesCountedLoop.Invoke.baseline4 0 2.855
>> 2.838
>> MethodHandlesCountedLoop.Invoke.baseline4 1 5.120
>> 5.179
>> MethodHandlesCountedLoop.Invoke.baseline4 10 11.875
>> 11.906
>> MethodHandlesCountedLoop.Invoke.baseline4 100 67.607
>> 67.374
>> MethodHandlesCountedLoop.Invoke.baselineMH3 0 9.734
>> 9.606
>> MethodHandlesCountedLoop.Invoke.baselineMH3 1 15.689
>> 15.674
>> MethodHandlesCountedLoop.Invoke.baselineMH3 10 68.912
>> 69.303
>> MethodHandlesCountedLoop.Invoke.baselineMH3 100 605.666
>> 606.432
>> MethodHandlesCountedLoop.Invoke.baselineMH4 0 14.561
>> 13.234
>> MethodHandlesCountedLoop.Invoke.baselineMH4 1 19.543
>> 19.773
>> MethodHandlesCountedLoop.Invoke.baselineMH4 10 71.977
>> 72.466
>> MethodHandlesCountedLoop.Invoke.baselineMH4 100 596.842
>> 602.469
>> MethodHandlesCountedLoop.Invoke.countedLoop3 0 49.339
>> 5.810
>> MethodHandlesCountedLoop.Invoke.countedLoop3 1 95.444
>> 7.441
>> MethodHandlesCountedLoop.Invoke.countedLoop3 10 508.746
>> 21.002
>> MethodHandlesCountedLoop.Invoke.countedLoop3 100
>> 4701.808 145.996
>> MethodHandlesCountedLoop.Invoke.countedLoop4 0 49.443
>> 5.798
>> MethodHandlesCountedLoop.Invoke.countedLoop4 1 98.721
>> 7.438
>> MethodHandlesCountedLoop.Invoke.countedLoop4 10 503.825
>> 21.049
>> MethodHandlesCountedLoop.Invoke.countedLoop4 100
>> 4681.803 147.020
>> MethodHandlesDoWhileLoop.Create.create N/A
>> 7628.312 9100.332
>> MethodHandlesDoWhileLoop.Invoke.baseline 1 3.868
>> 3.909
>> MethodHandlesDoWhileLoop.Invoke.baseline 10 16.480
>> 16.461
>> MethodHandlesDoWhileLoop.Invoke.baseline 100 144.260
>> 144.232
>> MethodHandlesDoWhileLoop.Invoke.baselineMH 1 14.434
>> 14.494
>> MethodHandlesDoWhileLoop.Invoke.baselineMH 10 92.542
>> 93.454
>> MethodHandlesDoWhileLoop.Invoke.baselineMH 100 877.480
>> 880.496
>> MethodHandlesDoWhileLoop.Invoke.doWhileLoop 1 26.791
>> 7.153
>> MethodHandlesDoWhileLoop.Invoke.doWhileLoop 10 158.985
>> 16.990
>> MethodHandlesDoWhileLoop.Invoke.doWhileLoop 100
>> 1391.746 130.946
>> MethodHandlesIteratedLoop.Create.create N/A
>> 13547.499 15478.542
>> MethodHandlesIteratedLoop.Invoke.baseline 0 2.973
>> 2.980
>> MethodHandlesIteratedLoop.Invoke.baseline 1 6.771
>> 6.658
>> MethodHandlesIteratedLoop.Invoke.baseline 10 14.955
>> 14.955
>> MethodHandlesIteratedLoop.Invoke.baseline 100 81.842
>> 82.582
>> MethodHandlesIteratedLoop.Invoke.baselineMH 0 14.893
>> 14.668
>> MethodHandlesIteratedLoop.Invoke.baselineMH 1 20.998
>> 21.304
>> MethodHandlesIteratedLoop.Invoke.baselineMH 10 73.677
>> 72.703
>> MethodHandlesIteratedLoop.Invoke.baselineMH 100 613.913
>> 614.475
>> MethodHandlesIteratedLoop.Invoke.iteratedLoop 0 33.583
>> 9.603
>> MethodHandlesIteratedLoop.Invoke.iteratedLoop 1 82.239
>> 14.433
>> MethodHandlesIteratedLoop.Invoke.iteratedLoop 10 448.356
>> 38.650
>> MethodHandlesIteratedLoop.Invoke.iteratedLoop 100
>> 4189.034 279.779
>> MethodHandlesLoop.Create.create N/A
>> 15505.970 17559.399
>> MethodHandlesLoop.Invoke0.baseline 1 3.179
>> 3.181
>> MethodHandlesLoop.Invoke0.baseline 10 5.952
>> 6.115
>> MethodHandlesLoop.Invoke0.baseline 100 50.942
>> 50.943
>> MethodHandlesLoop.Invoke0.loop 1 46.454
>> 5.353
>> MethodHandlesLoop.Invoke0.loop 10 514.230
>> 8.487
>> MethodHandlesLoop.Invoke0.loop 100
>> 5166.251 52.188
>> MethodHandlesLoop.Invoke1.loop 1 34.321
>> 5.277
>> MethodHandlesLoop.Invoke1.loop 10 430.839
>> 8.481
>> MethodHandlesLoop.Invoke1.loop 100
>> 4095.302 52.206
>> MethodHandlesTryFinally.baselineExceptional N/A 3.005
>> 3.002
>> MethodHandlesTryFinally.baselineMHExceptional N/A 166.316
>> 166.087
>> MethodHandlesTryFinally.baselineMHNormal N/A 9.337
>> 9.276
>> MethodHandlesTryFinally.baselineNormal N/A 2.696
>> 2.683
>> MethodHandlesTryFinally.create N/A 406.255
>> 406.594
>> MethodHandlesTryFinally.invokeTryFinallyExceptional N/A 154.121
>> 154.692
>> MethodHandlesTryFinally.invokeTryFinallyNormal N/A 5.350
>> 5.334
>> MethodHandlesWhileLoop.Create.create N/A
>> 12214.383 14503.515
>> MethodHandlesWhileLoop.Invoke.baseline 0 3.886
>> 3.888
>> MethodHandlesWhileLoop.Invoke.baseline 1 5.379
>> 5.377
>> MethodHandlesWhileLoop.Invoke.baseline 10 16.000
>> 16.201
>> MethodHandlesWhileLoop.Invoke.baseline 100 142.066
>> 143.338
>> MethodHandlesWhileLoop.Invoke.baselineMH 0 11.028
>> 11.012
>> MethodHandlesWhileLoop.Invoke.baselineMH 1 21.269
>> 21.159
>> MethodHandlesWhileLoop.Invoke.baselineMH 10 97.493
>> 97.656
>> MethodHandlesWhileLoop.Invoke.baselineMH 100 887.579
>> 886.532
>> MethodHandlesWhileLoop.Invoke.whileLoop 0 24.829
>> 7.108
>> MethodHandlesWhileLoop.Invoke.whileLoop 1 46.039
>> 8.573
>> MethodHandlesWhileLoop.Invoke.whileLoop 10 240.963
>> 21.088
>> MethodHandlesWhileLoop.Invoke.whileLoop 100
>> 2092.671 159.016
>>
>>
>>
