RFR: 8251994: VM crashed running TestComplexAddrExpr.java test with -XX:UseAVX=X [v2]

[Vladimir Kozlov]

On Wed, 28 Oct 2020 08:49:20 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Vladimir Kozlov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Use static const bool local variable
>
> src/hotspot/share/opto/superword.cpp line 94:
> 
>> 92: }
>> 93: 
>> 94: static const bool _do_vector_loop_experimental = false; // Experimental vectorization which uses data from loop unrolling.
> 
> For such purposes, I find debug VM flags a better option: they are constant in product binaries, easy to experiment/change from command-line with debug binaries, and enumerated in a single place.
> 
> Any reason to prefer `static const` declarations?

Adding any flag is exception - we should avoid it if it is not needed immediately. We have a lot of flags already.
As I said currently this code is broken - I want to remove it from debug builds too.
And it is easy to modify this value later - make it a field with the same name and initialize with diagnostic UseNewCode flag value as I did for testing.

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

PR: https://git.openjdk.java.net/jdk/pull/859