[jdk17] RFR: 8269285: Crash/miscompile in CallGenerator::for_method_handle_inline after JDK-8191998 [v5]

[Aleksey Shipilev]

On Wed, 30 Jun 2021 18:21:29 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> See the bug report for more details.
>> 
>> I believe the [JDK-8191998](https://bugs.openjdk.java.net/browse/JDK-8191998) change introduced a slight regression, where the speculative type join may empty the type. It would then crash on assert in `fastdebug` builds, or miscompile the null-check to `true` in `release` bits. New test captures both failure modes.
>> 
>> This is not a recent regression, but a regression nevertheless, so I would like to have that fix in JDK 17. Please review carefully, or speak up if you want to move it to JDK 18+ and then backport later.
>> 
>> Additional testing:
>>  - [x] New test fails without the patch, passes with it
>>  - [x] Linux x86_64 `fastdebug` `tier1`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   CompileCommand the test

Thank you, all.

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PR: https://git.openjdk.java.net/jdk17/pull/169