[8] RFR (XS): 8031695: CHA ignores default methods during analysis leading to incorrect code generation (original) (raw)
Lois Foltan lois.foltan at oracle.com
Wed Jan 22 12:48:32 PST 2014
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On 1/22/2014 3:34 PM, Vladimir Ivanov wrote:
John, Karen, thanks for review!
Special thanks goes to Lois for initial analysis and instructions how to reproduce the issue. It saved me lots of time.
Hi Vladimir, Thanks, your change looks good and as I mentioned earlier I tried it with the test case and all is fine. I would also be remiss not to point out that Christian Tornqvist also was very helpful in diagnosing key aspects about this problem. Thanks Christian! Lois
Best regards, Vladimir Ivanov On 1/22/14 11:16 PM, Karen Kinnear wrote: Looks good.
many thanks, Karen On Jan 22, 2014, at 12:29 PM, Vladimir Ivanov wrote:
http://cr.openjdk.java.net/~vlivanov/8031695/webrev.00/ https://bugs.openjdk.java.net/browse/JDK-8031695
CHA erroneously ignores default methods when looking for different versions of a method in a class hierarchy. Consider the following hierarchy: interface I { default void m() { ... }} class A implements I {} class C extends A { } class D extends A { public void m() { ... } } Call site: invokevirtual A.m() A.m resolves to I.m. Searching from A, CHA finds only D.m and concludes that D.m is the only implementation of I.m, since Dependencies::isconcretemethod returns false for I.m. But there is C with default implementation from I. So, if VM inlines D.m and then C's instance is passed as objectref, the wrong method is invoked (D.m instead of I.m). The fix is to take default methods into account doing CHA analysis and treat the call site as non-monomorphic when a concrete method is found for a default method. Conservative approach is chosen, since the fix is targeted for 8. Testing: failing application, regression test, vm.defmeth.testlist, JDK regression tests (java/util/, java/lang) Thanks! Best regards, Vladimir Ivanov
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