RFR: JDK-8330565 : C2: Multiple crashes with CTW after JDK-8316991 [v2]

[Vladimir Kozlov]

On Wed, 15 May 2024 04:11:36 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:
> 
>   Refactor split_castpp_load_through_phi

Looks good. This have to be tested.

-------------

PR Review: https://git.openjdk.org/jdk/pull/19147#pullrequestreview-2058008370