RFR: JDK-8330565 : C2: Multiple crashes with CTW after JDK-8316991 [v3]

[Cesar Soares Lucas]

On Wed, 15 May 2024 18:15:16 GMT, Cesar Soares Lucas <cslucas at openjdk.org> wrote:

>> The `# assert(false) failed: Bad graph detected in build_loop_late` failure was caused because a string concatenation optimization using [this method](https://github.com/openjdk/jdk/blob/819f3d6fc70ff6fe54ac5f9033c17c3dd4326aa5/src/hotspot/share/opto/graphKit.cpp#L4115) adds AddP and LoadN nodes to IR graph as NotNull _and_ because RAM was not "nullyfing" phis merging nullable pointers. I was only able to reproduce this problem using a classfile/jar compiled using an "old" version of JDK.. because newer version use InvokeDynamic to do string concatenation.
>> 
>> Tested with JTREG tier1-4 on Linux x86_64 & ARM64.
>
> Cesar Soares Lucas has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update test/hotspot/jtreg/compiler/c2/TestReduceAllocationAndNullableLoads.java
>   
>   -Xcomp implies -Xbatch
>   
>   Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>

Thank you all for reviewing!

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PR Comment: https://git.openjdk.org/jdk/pull/19147#issuecomment-2118208239