On Wed, 6 Jan 2021 20:05:07 GMT, Vladimir Kozlov <k...@openjdk.org> wrote:
>> I manually checked the usages of assignment operators for class DUIterator, >> DUIterator_Fast and DUIterator_Last. (Simply grep the class names in the >> source code and check the context). >> >> ~~I found there exist only a couple of re-assignment usages. However, I >> guess kind of reset operations are conducted in these sites, and I suspect >> the implementation of `operator=` might be good.~~ >> >> As I examined, only the following 3 sites are found where re-assignment >> happens >> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/cfgnode.cpp#L565 >> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/phaseX.cpp#L1878 >> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/split_if.cpp#L452 >> >> Please take `cfgnode.cpp` as an example. `j` is first assigned at line 568 >> and it would be assigned again if flag `progress` is true. ~~However, I >> suppose `j` gets reset at line 578 in such case.~~ Note that `j` might be >> re-assigned at line 578. However, it's self assignment and nothing is >> conducted. >> >> ~~It might be incorrect if I missed something.~~ >> Hope that this finding would be helpful to analyze this problem. > > Code is correct. _last should not be updated with additional assignments > which updates only node's information. Thanks a lot for your explanation @vnkozlov . ------------- PR: https://git.openjdk.java.net/jdk/pull/1874
