RFR: 8329077: C2 SuperWord: Add MoveD2L, MoveL2D, MoveF2I, MoveI2F

[Emanuel Peter]

On Thu, 31 Jul 2025 12:49:16 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> I've added support to vectorize `MoveD2L`, `MoveL2D`, `MoveF2I` and `MoveI2F` nodes. The implementation follows a similar pattern to what is done with conversion (`Conv*`) nodes. The tests in `TestCompatibleUseDefTypeSize` have been updated with the new expectations.
>> 
>> Also added a JMH benchmark which measures throughput (the higher the number the better) for methods that exercise these nodes. On darwin/aarch64 it shows:
>> 
>> 
>> Benchmark                                (seed)  (size)   Mode  Cnt      Base      Patch   Units   Diff
>> VectorBitConversion.doubleToLongBits          0    2048  thrpt    8  1168.782   1157.717  ops/ms    -1%
>> VectorBitConversion.doubleToRawLongBits       0    2048  thrpt    8  3999.387   7353.936  ops/ms   +83%
>> VectorBitConversion.floatToIntBits            0    2048  thrpt    8  1200.338   1188.206  ops/ms    -1%
>> VectorBitConversion.floatToRawIntBits         0    2048  thrpt    8  4058.248  14792.474  ops/ms  +264%
>> VectorBitConversion.intBitsToFloat            0    2048  thrpt    8  3050.313  14984.246  ops/ms  +391%
>> VectorBitConversion.longBitsToDouble          0    2048  thrpt    8  3022.691   7379.360  ops/ms  +144%
>> 
>> 
>> The improvements observed are a result of vectorization. The lack of vectorization in `doubleToLongBits` and `floatToIntBits` demonstrates that these changes do not affect their performance. These methods do not vectorize because of flow control.
>> 
>> I've run the tier1-3 tests on linux/aarch64 and didn't observe any regressions.
>
> test/micro/org/openjdk/bench/java/lang/VectorBitConversion.java line 1:
> 
>> 1: package org.openjdk.bench.java.lang;
> 
> I think this benchmark belongs with the other vectorization benchmarks under
> `test/micro/org/openjdk/bench/vm/compiler/Vector*`

It's not really a language feature, more for vm/compiler

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PR Review Comment: https://git.openjdk.org/jdk/pull/26457#discussion_r2245296534