RFR: 8302325: Wrong comment in java.base/share/native/libjimage/imageFile.hpp [v2]

[Jim Laskey]

On Tue, 14 Feb 2023 14:46:58 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

>> Could I please get a review of this trivial comment-only change? `imageFile.hpp`
>> describes some properties of the jimage file `lib/modules`. However, I don't think
>> the comment example matches current code in the JDK. [`ATTRIBUTE_OFFSET`](https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/jdk/internal/jimage/ImageLocation.java#L44) get
>> written to the image file with value `0x05` while the comment mentions it gets
>> written as `0x04`. I propose to fix the comment so that it matches the code.
>> 
>> In passing, I've also fixed a comment related to `ATTRIBUTE_END`. I think the point
>> being made there is about byte values of `[0x01..0x07]`, all would represent
>> `ATTRIBUTE_END`, as the upper `5` bits would be `0`. Therefore, byte `0x01` would equally
>> represent `ATTRIBUTE_END` as would `0x00` and `0x07` or any value in between.
>> 
>> Thoughts?
>
> Severin Gehwolf has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
> 
>  - Merge branch 'master' into jdk-8302325-imageFile
>  - Copyright dates updated.
>  - 8302325: Wrong comment in java.base/share/native/libjimage/imageFile.hpp

Changes requested by jlaskey (Reviewer).

src/java.base/share/native/libjimage/imageFile.hpp line 218:

> 216: // Notes:
> 217: //  - Even though ATTRIBUTE_END is used to mark the end of the attribute stream,
> 218: //      streams will contain non-zero byte values to represent lesser significant bits.

This change is not correct. Maybe it is badly worded but the point is that **zeroes can** occur in the stream so testing for zero is insufficient.

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/PerfectHashBuilder.java line 249:

> 247:                     // Attempt to pack entries until no collisions occur.
> 248:                     if (!collidedEntries(bucket, count)) {
> 249:                         // Failed to pack. Need to grow table.

Change copyright date to mark this change.

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PR: https://git.openjdk.org/jdk/pull/12533