On Tue, 3 Sep 2024 12:23:50 GMT, Shaojin Wen <s...@openjdk.org> wrote:
>> A small optimization, optimize the BufferWriter implementation and use of
>> ClassFile, provide faster patchInt and skip
>
> Shaojin Wen has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Update
> src/java.base/share/classes/jdk/internal/classfile/impl/BufWriterImpl.java
>
> Co-authored-by: Claes Redestad <claes.redes...@oracle.com>
This migration of write 0 to skip reveals that they are different. Good RFE.
(Maybe we can make the BufWriterImpl buffer growth to allocate non-initialized
array after the write 0 fixes)
src/java.base/share/classes/jdk/internal/classfile/impl/BufWriterImpl.java line
192:
> 190: }
> 191:
> 192: public void skip(int skipSize) {
Conceptually I would prefer to make such an API return an int for skipped index
so we can more easily patch later. But that is really optional.
src/java.base/share/classes/jdk/internal/classfile/impl/BufWriterImpl.java line
240:
> 238: public void writeIndexOrZero(PoolEntry entry) {
> 239: if (entry == null || entry.index() == 0)
> 240: skip(2);
Writing `0` CP index for `null` is mandated by the attributes that do so.
https://docs.oracle.com/javase/specs/jvms/se22/html/jvms-4.html#jvms-4.7.24-300-D-A.1
src/java.base/share/classes/jdk/internal/classfile/impl/DirectCodeBuilder.java
line 598:
> 596: bytecodesBufWriter.writeIndex(ref);
> 597: bytecodesBufWriter.writeU1(count);
> 598: bytecodesBufWriter.skip(1);
`0` is mandated:
https://docs.oracle.com/javase/specs/jvms/se22/html/jvms-6.html#jvms-6.5.invokeinterface
src/java.base/share/classes/jdk/internal/classfile/impl/DirectCodeBuilder.java
line 604:
> 602: writeBytecode(INVOKEDYNAMIC);
> 603: bytecodesBufWriter.writeIndex(ref);
> 604: bytecodesBufWriter.skip(2);
`0` is mandated:
https://docs.oracle.com/javase/specs/jvms/se22/html/jvms-6.html#jvms-6.5.invokedynamic
-------------
Changes requested by liach (Reviewer).
PR Review: https://git.openjdk.org/jdk/pull/20780#pullrequestreview-2277504778
PR Review Comment: https://git.openjdk.org/jdk/pull/20780#discussion_r1742099316
PR Review Comment: https://git.openjdk.org/jdk/pull/20780#discussion_r1742100573
PR Review Comment: https://git.openjdk.org/jdk/pull/20780#discussion_r1742102738
PR Review Comment: https://git.openjdk.org/jdk/pull/20780#discussion_r1742102983
