RFR: 8319875: Add macOS implementation for jcmd System.map

[Thomas Stuefe]

On Wed, 11 Sep 2024 18:22:00 GMT, Simon Tooke <stooke at openjdk.org> wrote:

> This is a port of #16301  to macOS.
> 
> System.map and System.dump_map are implemented using the macOS API and provide roughly the same information in the same format. Most of the heavy lifting was implemented by @tstuefe in https://github.com/openjdk/jdk/pull/16301 - this PR adds the macOS implementation and enables the common code for macOS 64 bit.
> 
> The System.map tests are also reworked to be cleaner for the three implementations.
> 
> [Sample output](https://github.com/user-attachments/files/17517412/sample.txt)

Nice work, thank you. Small nits inside. I have no time to test this extensively, but if the tests run through, it should be fine.

src/hotspot/os/bsd/memMapPrinter_macosx.cpp line 120:

> 118: 
> 119:   static const char* tagToStr(uint32_t user_tag) {
> 120:     switch (user_tag) {

You could reduce the code and remove duplications with an [x macro](https://en.wikipedia.org/wiki/X_macro) if you wanted.

src/hotspot/os/bsd/memMapPrinter_macosx.cpp line 360:

> 358:       break;
> 359:     } else if (retval < (int)sizeof(region_info)) {
> 360:       fatal("proc_pidinfo() returned %d", retval);

I would make this an assert, and return without printing anything in release.

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PR Review: https://git.openjdk.org/jdk/pull/20953#pullrequestreview-2395601473
PR Review Comment: https://git.openjdk.org/jdk/pull/20953#discussion_r1816880506
PR Review Comment: https://git.openjdk.org/jdk/pull/20953#discussion_r1816894551