RFR(S) 8161598,,Kitchensink fails: assert(nm->insts_contains(original_pc)) failed: original PC must be in nmethod/CompiledMethod

dean.long at oracle.com dean.long at oracle.com
Fri Aug 12 20:19:03 UTC 2016




On 8/12/16 6:46 AM, Frederic Parain wrote:
> Dean,
> In file macroAssembler_x86.cpp, could it be possible to
> get rid of the clear_pc argument? It seems completely
> useless now.
> Fred
> On 08/09/2016 01:39 PM, dean.long at oracle.com wrote:
>> Ping.
>> dl
>> On 8/4/16 3:28 PM, dean.long at oracle.com wrote:
>>> https://bugs.openjdk.java.net/browse/JDK-8161598
>>> http://cr.openjdk.java.net/~dlong/8161598/webrev/
>>> Sorry, this issue is Confidential.  The problem is similar to 8029441,
>>> where we suspend a thread and use pd_get_top_frame_for_profiling() to
>>> get the top frame for stack walking.  The problem is "last Java frame"
>>> anchor frames on x86. In lots of places we do not store last_Java_pc.
>>> This is OK in the synchronous stack walk case done by the current
>>> thread.  But in the asynchronous case, there are small windows where
>>> it's not always safe to get PC from sp[-1].
>>> The solution is not to treat x86 anchor frames as "always walkable".
>>> Instead, we follow the example of sparc and make them walking by
>>> filling in last_Java_pc when it's safe.
>>> I went for the minimal fix, resetting clear_pc to true in
>>> reset_last_Java_frame() but not changing the API and all the callers.
>>> I can fix this if reviewers feel strongly about it.
>>> dl

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