Ensure resolved final methods are called directly #4944
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In 3b2830e genInvokeVirtual() was modified to detect resolved private methods for nestmates. If a private method is found, it generates a direct call, and otherwise (including when the method reference is unresolved) it generates a virtual call. In order to generate a virtual call, it queries the constant pool a second time, and if the constant pool entry was originally unresolved, it might have become resolved since. In this case, ilgen could fail to identify for a resolved call that the called method is final, and generate an indirect instead of a direct call. Normally it's harmless for the call to be indirect, but there are a number of final methods recognized by the JIT compiler that undergo transformations assuming that calls to them are direct. To prevent this problem, genInvokeVirtual() will now re-read method from the result of findOrCreateVirtualMethodSymbol() whenever that result is resolved. Signed-off-by: Devin Papineau <devinmp@ca.ibm.com> (cherry picked from commit 8a1ec0b)
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@jdmpapin Can you link to the PR against the master branch? It makes it clear that this fix has already gone into the mainline is being ported to the 0.13.0 release |
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I've edited the link into the initial comment |
pshipton
approved these changes
Mar 1, 2019
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In 3b2830e
genInvokeVirtual()was modified to detect resolved private methods for nestmates. If a private method is found, it generates a direct call, and otherwise (including when the method reference is unresolved) it generates a virtual call. In order to generate a virtual call, it queries the constant pool a second time, and if the constant pool entry was originally unresolved, it might have become resolved since. In this case, ilgen could fail to identify for a resolved call that the called method is final, and generate an indirect instead of a direct call. Normally it's harmless for the call to be indirect, but there are a number of final methods recognized by the JIT compiler that undergo transformations assuming that calls to them are direct.To prevent this problem,
genInvokeVirtual()will now re-read method from the result offindOrCreateVirtualMethodSymbol()whenever that result is resolved.Fixes #4334
Master PR is #4860