Check for VarHandle's MethodType table only when necessary #20329
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A VarHandle can be initialized such that its access mode method invocation behaves like a MethodHandle.invokeExact invocation. We can check if this is the case by checking whether the VarHandle.exact field was set to true. In such a case, an additional check is necessary, where we need to verify whether AccessDescriptor.symbolicMethodTypeExact field matches the corresponding entry in the MethodType table, failing which the JIT should abort trying to lookup the MethodHandleTable. The MethodType table would only be initialized for a VarHandle if the VarHandle.exact field was initialized as true. Therefore, by moving the check for whether the MethodType table is valid to occur only after we confirm that the VarHandle has invokeExact behaviour, we prevent prematurely aborting the MH entry lookup in getMethodHandleTableEntryIndex when the MT table is not initialized. Signed-off-by: Nazim Bhuiyan <[email protected]>
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@jdmpapin Requesting your review. |
jdmpapin
approved these changes
Oct 10, 2024
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Jenkins test sanity all jdk17 |
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Jenkins test sanity alinux,xlinux jdk17 |
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A
VarHandlecan be initialized such that its access mode method invocation behaves like aMethodHandle.invokeExactinvocation. We can check if this is the case by checking whether theVarHandle.exactfield was set to true. In such a case, an additional check is necessary, where we need to verify whetherAccessDescriptor.symbolicMethodTypeExactfield matches the corresponding entry in theMethodTypetable, failing which the JIT should abort trying to lookup theMethodHandletable.The
MethodTypetable would only be initialized for aVarHandleif theVarHandle.exactfield was initialized as true. Therefore, by moving the check for whether theMethodTypetable is valid to occur only after we confirm that theVarHandlehasinvokeExactbehaviour, we prevent prematurely aborting the MH entry lookup ingetMethodHandleTableEntryIndexwhen the MT table is not initialized.