Hi Kim,
Thanks for the review.
On 7/8/19 7:08 PM, Kim Barrett wrote:
On Jul 6, 2019, at 9:53 AM, Daniel D. Daugherty <daniel.daughe...@oracle.com>
wrote:
Greetings,
During the code review for the following fix:
JDK-8227117 normal interpreter table is not restored after single stepping
with TLH
https://bugs.openjdk.java.net/browse/JDK-8227117
Erik O. noticed a potential race with templateInterpreter.cpp: copy_table()
depending on C++ compiler optimizations. The following bug is being used
to fix this issue:
JDK-8227338 templateInterpreter.cpp: copy_table() needs to be safer
https://bugs.openjdk.java.net/browse/JDK-8227338
Here's the webrev URL:
http://cr.openjdk.java.net/~dcubed/8227338-webrev/0_for_jdk14/
This fix has been tested via Mach5 Tier[1-3] on Oracle's usual platforms.
Mach5 tier[4-6] is running now. It has also been tested with the manual
jdb test from JDK-8227117 using 'release' and 'fastdebug' bits.
Thanks, in advance, for questions, comments or suggestions.
Dan
[This review is ignoring the issues around the current implementation
of atomic copies discussed elsewhere in this thread. I assume those
will be addressed elsewhere.]
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src/hotspot/share/interpreter/templateInterpreter.cpp
286 while (size-- > 0) *to++ = *from++;
[pre-existing]
This ought to be using Copy::disjoint_words. That's even more obvious
in conjunction with the change to use Copy::disjoint_words_atomic in
the non-safepoint case.
I can make that change. Is there a specific advantage/reason that you
have in mind here?
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src/hotspot/share/interpreter/templateInterpreter.cpp
284 if (SafepointSynchronize::is_at_safepoint()) {
I wonder how much benefit we really get from having distinct safepoint
and non-safepoint cases, rather than just unconditionally using
Copy::disjoint_words_atomic.
Sorry, I don't know the answer to that. My intention was to use
Copy::disjoint_words_atomic() only in the case where I knew that
I needed it so no potential impact on existing uses at a safepoint.
Thanks for the review.
Dan
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