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https://issues.apache.org/jira/browse/BCEL-195?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Emmanuel Bourg updated BCEL-195:
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Description: [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. (was: revision 1532198 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.)
> 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
> Reporter: Mark Roberts
>
> [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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