RFR: 8281429: PhiNode::Value() is too conservative for tripcount of CountedLoop [v3]

[Roland Westrelin]

On Wed, 23 Mar 2022 07:50:19 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> Roland Westrelin has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:
>> 
>>  - review
>>  - Merge branch 'master' into JDK-8281429
>>  - Update src/hotspot/share/opto/cfgnode.cpp
>>    
>>    Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
>>  - Update src/hotspot/share/opto/cfgnode.cpp
>>    
>>    Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
>>  - Update src/hotspot/share/opto/loopnode.cpp
>>    
>>    Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
>>  - Update src/hotspot/share/opto/loopnode.cpp
>>    
>>    Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
>>  - fix & test
>
> The following test triggers `assert(hi->hi_as_long() > lo->lo_as_long()) failed: no iterations?` when executed with `-XX:-TieredCompilation -Xbatch`:
> 
> ``` 
> public class Test {
>     public static void main(String[] args) {
>         for (long l = (Long.MAX_VALUE - 1); l != (Long.MIN_VALUE + 100_000); l++) {
>             if (l == 0) {
>                 throw new RuntimeException("Test failed");
>             }
>         }
>     }
> }
> 
> 
> Please add it as regression test.

Thanks @TobiHartmann
I updated the change again: I removed a change from loopTransform.cpp that's no longer necessary after 8273115.

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PR: https://git.openjdk.java.net/jdk/pull/7823