RFR: 8260716 : Assert in MacroAssembler::clear_mem with -XX:-IdealizeClearArrayNode [v6]

[Tobias Hartmann]

On Wed, 17 Mar 2021 16:34:09 GMT, Jamsheed Mohammed C M <jcm at openjdk.org> wrote:

>> [8257772](https://bugs.openjdk.java.net/browse/JDK-8257772) added a new rule(rep_stos_im), modified old rules(rep_stos) missed adding proper predicates relating to UseAVX and supports_avx512vlbw
>> 
>> Testing : Running, added in JBS
>
> Jamsheed Mohammed C M has updated the pull request incrementally with one additional commit since the last revision:
> 
>   jcheck failure test

Changes requested by thartmann (Reviewer).

test/hotspot/jtreg/compiler/codegen/ClearArrayTest.java line 28:

> 26:  * @bug 8260716
> 27:  * @summary Test for correct code generation by the JIT
> 28:  * @run main/othervm -Xbatch -XX:CompileCommand=compileonly,*ClearArrayTest.test -XX:-IdealizeClearArrayNode compiler.codegen.ClearArrayTest

Your test will fail with a product build because `IdealizeClearArrayNode` is a diagnostic VM option:
Error: VM option 'IdealizeClearArrayNode' is diagnostic and must be enabled via -XX:+UnlockDiagnosticVMOptions.

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PR: https://git.openjdk.java.net/jdk/pull/3035