RFR: 8253717: Relocate stack overflow code out of thread.hpp/cpp [v5]

[Coleen Phillimore]

On Wed, 7 Oct 2020 18:41:09 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> src/hotspot/share/runtime/stackOverflow.hpp line 34:
>> 
>>> 32:
>>> 33: // StackOverflow handling is encapsulated in this class.  This class contains state variables
>>> 34: // for each JavaThread that implement stack overflow checking and guard page implementation.
>> 
>> This clause doesn't read quite right... Perhaps:
>> 
>> `// for each JavaThread that implement stack overflow checking and guard page functionality.`
>> 
>> The "that implement" and "guard page implementation." phrases in the same clause
>> just don't read right... Your call on making a change here.
>
> // StackOverflow handling is encapsulated in this class.  This class contains state variables
> // for each JavaThread that are used to detect stack overflow though explicit checks or through
> // checks in the signal handler when stack banging into guard pages causes a trap.
> // The state variables also record whether guard pages are enabled or disabled.
> 
> Does this sound better?  It's more descriptive but hopefully still summarizing.

Re: your comment above.  I did just move the code but some of the review comments are on the existing code.  I did end
up adding a function initialize_stack_zone_sizes and removing the set*zone functions as a result and changed some
comments.  And added some consts.

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PR: https://git.openjdk.java.net/jdk/pull/522