[9] RFR (S): 8148994: Replacing MH::invokeBasic with a direct call breaks LF customization
Vladimir Ivanov
vladimir.x.ivanov at oracle.com
Thu Feb 4 15:51:35 UTC 2016
http://cr.openjdk.java.net/~vlivanov/8148994/webrev.00
https://bugs.openjdk.java.net/browse/JDK-8148994
JDK-8072008 [1] introduced an optimization to bypass linker calls in
generated code when target method can't be inlined.
Unfortunately, it doesn't work well with MH::invokeBasic(), because it
clashes with LambdaForm customization: if a call is not inlined, it is
important for performance to update (customize) corresponding LambdaForm
on-the-fly. MH::invokeBasic() linker does MH -> LF -> Method* ->
_from_compiled_entry traversal on every invocation, while direct call
points right to the _from_compiled_entry. So, any LambdaForm updates
aren't visible until recompilation.
The fix is to keep MH::invokeBasic linker, so up-to-date LambdaForm
instance is used on every invocation.
Also, cleaned up relevant tests a bit.
Testing: octane, JPRT.
Best regards,
Vladimir Ivanov
[1] https://bugs.openjdk.java.net/browse/JDK-8072008
"Emit direct call instead of linkTo* for recursive indy/MH.invoke*
calls"
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