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https://issues.apache.org/jira/browse/BCEL-195?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14717742#comment-14717742
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Sebb commented on BCEL-195:
---------------------------
URL: http://svn.apache.org/r1698243
Log:
BCEL-195 addition of hashCode() to generic/Instruction.java breaks Targeters.
Never make distinct BranchInstructions compare equal
Modified:
commons/proper/bcel/trunk/src/changes/changes.xml
commons/proper/bcel/trunk/src/main/java/org/apache/commons/bcel6/generic/InstructionComparator.java
commons/proper/bcel/trunk/src/test/java/org/apache/commons/bcel6/generic/InstructionHandleTestCase.java
I thought better of the equality short-cut check (added as an afterthought).
Although that check would make sense for ordinary HashSet usage, the conditions
here are different.
The test still passed, but I suspect it would cause problems.
[We could still add the equality check after rejecting BIs]
URL: http://svn.apache.org/r1698244
Log:
BCEL-195 addition of hashCode() to generic/Instruction.java breaks Targeters.
Never make BranchInstructions compare equal
Revert short-cut equality check because that would allow a single BI to be
shared.
Modified:
commons/proper/bcel/trunk/src/main/java/org/apache/commons/bcel6/generic/InstructionComparator.java
> addition of hashCode() to generic/Instruction.java breaks Targeters
> -------------------------------------------------------------------
>
> Key: BCEL-195
> URL: https://issues.apache.org/jira/browse/BCEL-195
> Project: Commons BCEL
> Issue Type: Bug
> Components: Main
> Affects Versions: 6.0
> Reporter: Mark Roberts
> Attachments: compare.diff, select-init.diff
>
>
> [Revision 1532198|http://svn.apache.org/r1532198] added a {{hashCode()}}
> function to the Instruction class. Unfortunately, this breaks the
> Instruction targeting mechanism. I understand the goal of trying to reuse
> instructions - an 'iadd' is the same as any other 'iadd'. However, one
> 'goto 50' is not the same as another 'goto 50' due to the way Targeters are
> implemented. If branch instructions are reused, then only one entry gets put
> on the Targeter list. So when some api is used to modify the instruction
> list and location 50 becomes location 52 ONLY ONE of the branches gets
> updated. A very bad thing. So unless you modify the hash to special case
> branch instructions (and there might be other instructions needing special
> treatment as well) its broken. We fixed it by simply commenting the hash out
> to make things like they used to be and all works great.
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