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https://issues.apache.org/jira/browse/BCEL-144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14708547#comment-14708547
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Sebb commented on BCEL-144:
---------------------------
We also would need some unit tests.
> Branch target offset too large for short
> ----------------------------------------
>
> Key: BCEL-144
> URL: https://issues.apache.org/jira/browse/BCEL-144
> Project: Commons BCEL
> Issue Type: Bug
> Components: Main
> Reporter: cfeldmann
> Assignee: Apache Commons Developers
> Labels: PatchAvailable
> Attachments: large_branch_target_fix.patch
>
>
> When BCEL encounters a BranchInstruction offset that is >= 32767, it throws
> the following exception:
> {code}
> com.sitraka.pas.sandbox.org.apache.bcel.generic.ClassGenException: Branch
> target offset too large for short
> at
> com.sitraka.pas.sandbox.org.apache.bcel.generic.BranchInstruction.dump(BranchInstruction.java:99)
> at
> com.sitraka.pas.sandbox.org.apache.bcel.generic.InstructionList.getByteCode(InstructionList.java:993)
> at
> com.sitraka.pas.sandbox.org.apache.bcel.generic.MethodGen.getMethod(MethodGen.java:616)
> {code}
> BCEL-66 was previously filed about this exception and closed because the
> class that was causing the error and the suggested solution were both
> violating the rules of the language. My situation is a little different, so I
> am filing a new bug.
> I am inserting bytecodes into a method that is large, but within the limits
> defined by the language. Due to the size of the method, a number of the
> branch targets are large, but still small enough to fit in a short. After I
> insert bytecodes, the method size is still smaller than the method size limit
> but the large branch targets increase enough so that they no longer fit in a
> short and the exception occurs.
> I have solved the problem and am including a patch. My solution is to check
> the InstructionList for any branch targets that are too large to fit in a
> short and append a goto and a goto_w after every such instruction. I set the
> goto's target to the instruction that followed the branch instruction before
> I did my append so that the default behaviour is to maintain the original
> path of execution and jump over the goto_w. I set the goto_w's target to the
> branch instruction's target, then I set the branch instruction's target to
> the goto_w. I am doing this only for IfInstructions because JSRs, GOTOs and
> Selects seem to handle large branch targets in their implementations of
> updatePosition. This works and is within the rules defined by the language as
> far as I can tell.
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