Summary
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Deprecate the option -XX: FieldsAllocationStyle option.  By default it is 1 and other values will not lead to better performance or observable benefits.

Problem
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Flags allowing users to affect the layout of fields in Java classes give users unwelcome control over internal implementation details.  This option determines allocation order of fields:

    "0 - type based with oops first, "
    "1 - with oops last, "
    "2 - oops in super and sub classes are together"

Testing when the option was created showed that allocation style 1 was best, and this option has not been used by customers for performance improvements.

With @contended, padding can be added to prevent false sharing, if needed.

Deprecating and removing this option will allow for efficient implementation of inline types for valhalla.

Solution
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Deprecate the option and continue affect layout with the option.

Users will now get the following message when running: 'java -XX:+FieldsAllocationStyle ...'

Java HotSpot(TM) 64-Bit Server VM warning: Option FieldsAllocationStyle was deprecated in version 14.0 and will likely be removed in a future release.

Specification
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Deprecate the -XX: FieldsAllocationStyle option in JDK-14 and issue the above warning message when the option is used.