Re: RFR: 8283667: [vectorapi] Vectorization for masked load with IOOBE with predicate feature [v6]
On Tue, 7 Jun 2022 04:29:40 GMT, Xiaohong Gong wrote:
>> Currently the vector load with mask when the given index happens out of the
>> array boundary is implemented with pure java scalar code to avoid the IOOBE
>> (IndexOutOfBoundaryException). This is necessary for architectures that do
>> not support the predicate feature. Because the masked load is implemented
>> with a full vector load and a vector blend applied on it. And a full vector
>> load will definitely cause the IOOBE which is not valid. However, for
>> architectures that support the predicate feature like SVE/AVX-512/RVV, it
>> can be vectorized with the predicated load instruction as long as the
>> indexes of the masked lanes are within the bounds of the array. For these
>> architectures, loading with unmasked lanes does not raise exception.
>>
>> This patch adds the vectorization support for the masked load with IOOBE
>> part. Please see the original java implementation (FIXME: optimize):
>>
>>
>> @ForceInline
>> public static
>> ByteVector fromArray(VectorSpecies species,
>>byte[] a, int offset,
>>VectorMask m) {
>> ByteSpecies vsp = (ByteSpecies) species;
>> if (offset >= 0 && offset <= (a.length - species.length())) {
>> return vsp.dummyVector().fromArray0(a, offset, m);
>> }
>>
>> // FIXME: optimize
>> checkMaskFromIndexSize(offset, vsp, m, 1, a.length);
>> return vsp.vOp(m, i -> a[offset + i]);
>> }
>>
>> Since it can only be vectorized with the predicate load, the hotspot must
>> check whether the current backend supports it and falls back to the java
>> scalar version if not. This is different from the normal masked vector load
>> that the compiler will generate a full vector load and a vector blend if the
>> predicate load is not supported. So to let the compiler make the expected
>> action, an additional flag (i.e. `usePred`) is added to the existing
>> "loadMasked" intrinsic, with the value "true" for the IOOBE part while
>> "false" for the normal load. And the compiler will fail to intrinsify if the
>> flag is "true" and the predicate load is not supported by the backend, which
>> means that normal java path will be executed.
>>
>> Also adds the same vectorization support for masked:
>> - fromByteArray/fromByteBuffer
>> - fromBooleanArray
>> - fromCharArray
>>
>> The performance for the new added benchmarks improve about `1.88x ~ 30.26x`
>> on the x86 AVX-512 system:
>>
>> Benchmark before After Units
>> LoadMaskedIOOBEBenchmark.byteLoadArrayMaskIOOBE 737.542 1387.069 ops/ms
>> LoadMaskedIOOBEBenchmark.doubleLoadArrayMaskIOOBE 118.366 330.776 ops/ms
>> LoadMaskedIOOBEBenchmark.floatLoadArrayMaskIOOBE 233.832 6125.026 ops/ms
>> LoadMaskedIOOBEBenchmark.intLoadArrayMaskIOOBE233.816 7075.923 ops/ms
>> LoadMaskedIOOBEBenchmark.longLoadArrayMaskIOOBE 119.771 330.587 ops/ms
>> LoadMaskedIOOBEBenchmark.shortLoadArrayMaskIOOBE 431.961 939.301 ops/ms
>>
>> Similar performance gain can also be observed on 512-bit SVE system.
>
> Xiaohong Gong has updated the pull request with a new target base due to a
> merge or a rebase. The pull request now contains seven commits:
>
> - Add constant OFFSET_IN_RANGE and OFFSET_OUT_OF_RANGE
> - Merge branch 'jdk:master' into JDK-8283667
> - Merge branch 'jdk:master' into JDK-8283667
> - Use integer constant for offsetInRange all the way through
> - Rename "use_predicate" to "needs_predicate"
> - Rename the "usePred" to "offsetInRange"
> - 8283667: [vectorapi] Vectorization for masked load with IOOBE with
> predicate feature
LGTM.
-
PR: https://git.openjdk.java.net/jdk/pull/8035
Re: RFR: 8283667: [vectorapi] Vectorization for masked load with IOOBE with predicate feature [v6]
> Currently the vector load with mask when the given index happens out of the
> array boundary is implemented with pure java scalar code to avoid the IOOBE
> (IndexOutOfBoundaryException). This is necessary for architectures that do
> not support the predicate feature. Because the masked load is implemented
> with a full vector load and a vector blend applied on it. And a full vector
> load will definitely cause the IOOBE which is not valid. However, for
> architectures that support the predicate feature like SVE/AVX-512/RVV, it can
> be vectorized with the predicated load instruction as long as the indexes of
> the masked lanes are within the bounds of the array. For these architectures,
> loading with unmasked lanes does not raise exception.
>
> This patch adds the vectorization support for the masked load with IOOBE
> part. Please see the original java implementation (FIXME: optimize):
>
>
> @ForceInline
> public static
> ByteVector fromArray(VectorSpecies species,
>byte[] a, int offset,
>VectorMask m) {
> ByteSpecies vsp = (ByteSpecies) species;
> if (offset >= 0 && offset <= (a.length - species.length())) {
> return vsp.dummyVector().fromArray0(a, offset, m);
> }
>
> // FIXME: optimize
> checkMaskFromIndexSize(offset, vsp, m, 1, a.length);
> return vsp.vOp(m, i -> a[offset + i]);
> }
>
> Since it can only be vectorized with the predicate load, the hotspot must
> check whether the current backend supports it and falls back to the java
> scalar version if not. This is different from the normal masked vector load
> that the compiler will generate a full vector load and a vector blend if the
> predicate load is not supported. So to let the compiler make the expected
> action, an additional flag (i.e. `usePred`) is added to the existing
> "loadMasked" intrinsic, with the value "true" for the IOOBE part while
> "false" for the normal load. And the compiler will fail to intrinsify if the
> flag is "true" and the predicate load is not supported by the backend, which
> means that normal java path will be executed.
>
> Also adds the same vectorization support for masked:
> - fromByteArray/fromByteBuffer
> - fromBooleanArray
> - fromCharArray
>
> The performance for the new added benchmarks improve about `1.88x ~ 30.26x`
> on the x86 AVX-512 system:
>
> Benchmark before After Units
> LoadMaskedIOOBEBenchmark.byteLoadArrayMaskIOOBE 737.542 1387.069 ops/ms
> LoadMaskedIOOBEBenchmark.doubleLoadArrayMaskIOOBE 118.366 330.776 ops/ms
> LoadMaskedIOOBEBenchmark.floatLoadArrayMaskIOOBE 233.832 6125.026 ops/ms
> LoadMaskedIOOBEBenchmark.intLoadArrayMaskIOOBE233.816 7075.923 ops/ms
> LoadMaskedIOOBEBenchmark.longLoadArrayMaskIOOBE 119.771 330.587 ops/ms
> LoadMaskedIOOBEBenchmark.shortLoadArrayMaskIOOBE 431.961 939.301 ops/ms
>
> Similar performance gain can also be observed on 512-bit SVE system.
Xiaohong Gong has updated the pull request with a new target base due to a
merge or a rebase. The pull request now contains seven commits:
- Add constant OFFSET_IN_RANGE and OFFSET_OUT_OF_RANGE
- Merge branch 'jdk:master' into JDK-8283667
- Merge branch 'jdk:master' into JDK-8283667
- Use integer constant for offsetInRange all the way through
- Rename "use_predicate" to "needs_predicate"
- Rename the "usePred" to "offsetInRange"
- 8283667: [vectorapi] Vectorization for masked load with IOOBE with predicate
feature
-
Changes: https://git.openjdk.java.net/jdk/pull/8035/files
Webrev: https://webrevs.openjdk.java.net/?repo=jdk=8035=05
Stats: 453 lines in 44 files changed: 174 ins; 21 del; 258 mod
Patch: https://git.openjdk.java.net/jdk/pull/8035.diff
Fetch: git fetch https://git.openjdk.java.net/jdk pull/8035/head:pull/8035
PR: https://git.openjdk.java.net/jdk/pull/8035
