RFR: 8339290: Optimize ClassFile Utf8EntryImpl#writeTo [v3]

[Shaojin Wen]

On Fri, 30 Aug 2024 18:46:08 GMT, Chen Liang <liach at openjdk.org> wrote:

>> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Suggestions from @cl4es, rename hasNegativeOrZeros to isLatin1GreaterThanZero
>
> If a non-ascii is in the middle or the end of a string, this patch may add an overhead. Offline benchmark results show that this actually brings a regression in the startup of a jetty server.

Thanks to @liach for providing new ideas for benchmarking. Here are the new performance data

## 1. TieredStopAtLevel=1

### 1.1 Script

git remote add wenshao git at github.com:wenshao/jdk.git
git fetch wenshao

# baseline
git checkout 12550c3ea58a6405de21cc185fa972378b534120
make test TEST="micro:java.lang.classfile.Utf8EntryWriteTo" MICRO="VM_OPTIONS=-Xint -XX:TieredStopAtLevel=1"

# current
git checkout 99143fdb3a11140d5c9f067c144629def344666d
make test TEST="micro:java.lang.classfile.Utf8EntryWriteTo" MICRO="VM_OPTIONS=-Xint -XX:TieredStopAtLevel=1"



### 1.2 MacBook M1 Pro Performance Numbers


-# baseline
-Benchmark                   (charType)  Mode  Cnt      Score     Error  Units
-Utf8EntryWriteTo.writeTo         ascii  avgt    9  26818.441 ? 476.844  ns/op
-Utf8EntryWriteTo.writeTo  utf8_2_bytes  avgt    9  33001.261 ?  78.130  ns/op
-Utf8EntryWriteTo.writeTo  utf8_3_bytes  avgt    9  40134.337 ? 103.220  ns/op
-Utf8EntryWriteTo.writeTo         emoji  avgt    9  58745.488 ? 205.561  ns/op

+# current
+Benchmark                   (charType)  Mode  Cnt      Score     Error  Units
+Utf8EntryWriteTo.writeTo         ascii  avgt    9  10795.072 ? 254.952  ns/op
+Utf8EntryWriteTo.writeTo  utf8_2_bytes  avgt    9  14661.640 ?  64.254  ns/op
+Utf8EntryWriteTo.writeTo  utf8_3_bytes  avgt    9  17129.657 ? 194.146  ns/op
+Utf8EntryWriteTo.writeTo         emoji  avgt    9  24167.056 ? 319.348  ns/op


|   | charType | baseline  | current | delta |
| --- | --- | --- | --- | --- |
| Utf8EntryWriteTo.writeTo | ascii | 26818.441 | 10795.072 | 148.43% |
| Utf8EntryWriteTo.writeTo | utf8_2_bytes | 33001.261 | 14661.640 | 125.09% |
| Utf8EntryWriteTo.writeTo | utf8_3_bytes | 40134.337 | 17129.657 | 134.30% |
| Utf8EntryWriteTo.writeTo | emoji | 58745.488 | 24167.056 | 143.08% |


## 2. Non-JVM Options

### 2.1 Script

git remote add wenshao git at github.com:wenshao/jdk.git
git fetch wenshao

# baseline
git checkout 12550c3ea58a6405de21cc185fa972378b534120
make test TEST="micro:java.lang.classfile.Utf8EntryWriteTo"

# current
git checkout 99143fdb3a11140d5c9f067c144629def344666d
make test TEST="micro:java.lang.classfile.Utf8EntryWriteTo"


### 2.2 MacBook M1 Pro Performance Numbers


-# baseline
-Benchmark                   (charType)  Mode  Cnt    Score   Error  Units
-Utf8EntryWriteTo.writeTo         ascii  avgt    9  268.824 ? 2.834  ns/op
-Utf8EntryWriteTo.writeTo  utf8_2_bytes  avgt    9  308.376 ? 1.581  ns/op
-Utf8EntryWriteTo.writeTo  utf8_3_bytes  avgt    9  343.579 ? 1.331  ns/op
-Utf8EntryWriteTo.writeTo         emoji  avgt    9  463.350 ? 2.090  ns/op

+# current
+Benchmark                   (charType)  Mode  Cnt    Score     Error  Units
+Utf8EntryWriteTo.writeTo         ascii  avgt    9  139.114 ?   0.873  ns/op
+Utf8EntryWriteTo.writeTo  utf8_2_bytes  avgt    9  158.509 ?   0.772  ns/op
+Utf8EntryWriteTo.writeTo  utf8_3_bytes  avgt    9  170.437 ?   2.442  ns/op
+Utf8EntryWriteTo.writeTo         emoji  avgt    9  268.832 ? 112.823  ns/op


|   | charType | baseline  | current | delta |
| --- | --- | --- | --- | --- |
| Utf8EntryWriteTo.writeTo | ascii | 268.824 | 139.114 | 93.24% |
| Utf8EntryWriteTo.writeTo | utf8_2_bytes | 308.376 | 158.509 | 94.55% |
| Utf8EntryWriteTo.writeTo | utf8_3_bytes | 343.579 | 170.437 | 101.59% |
| Utf8EntryWriteTo.writeTo | emoji | 463.350 | 268.832 | 72.36% |

-------------

PR Comment: https://git.openjdk.org/jdk/pull/20772#issuecomment-2325008818