RFR: JDK-8318636: Add jcmd to print annotated process memory map [v6]

[Johan Sjölen]

On Wed, 1 Nov 2023 07:32:23 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> src/hotspot/share/nmt/memMapPrinter.cpp line 79:
>> 
>>> 77:   const void* const min = MAX2(from1, from2);
>>> 78:   const void* const max = MIN2(to1, to2);
>>> 79:   return min < max;
>> 
>> I had to rewrite it as:
>> 
>> `return MAX2(from1, from2) < MIN2(to1, to2);`
>> 
>> to make sure I understand it, or better yet, why not have it as a macros?
>> 
>> `#define RANGE_INTERSECT(min, max) (return MAX2(from1, from2) < MIN2(to1, to2))`
>> 
>>  MAX2 and MIN2 are macros already and we're not doing anything fancy here.
>
> I'll do the former, that is clearer I agree, but leave the latter out (I assume with the macro you mean add it to globalDefenitions.hpp).
> 
> I fear that a lot of bikeshedding and general discussions would start, and to do it properly needs a bit more time. Because we really would benefit from having a nice templatized utility classes for ranges. Like MemRegion, but that one is tied to HeapWord* I think.

`MAX2` and `MIN2` are not macros, they're `constexpr` free functions, and that's what a `RANGE_INTERSECT` free function should be also. Unexpected because of their names, I know.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16301#discussion_r1378579302