RFR: 8171508: Remove -Dsun.java.launcher.is_altjvm option [v6]

[David Holmes]

On Wed, 9 Apr 2025 06:19:52 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

>> The `-Dsun.java.launcher.is_altjvm` option is only used in the gtest launcher and has no relationship with the similarly named `-XXaltjvm` option. The gtest launcher also sets the `-XX:+ExecutingUnitTests` option. This RFE involves removing the `-Dsun.java.launcher.is_altjvm` option, capturing the `-XX:+ExecutingUnitTests` option in Arguments::process_sun_java_launcher_properties() so that the os::jvm_path() can check if the option is set before using JAVA_HOME setting.
>> 
>> Passed tiers 1 - 3 testing.
>
> Calvin Cheung has updated the pull request incrementally with one additional commit since the last revision:
> 
>   simplify the code by using stringStream

Looks okay. Some additional possible cleanup now you are using the stringStream.

src/hotspot/os/aix/os_aix.cpp line 1330:

> 1328: 
> 1329:       len = strlen(buf);
> 1330:       assert(len < buflen, "Ran out of buffer room");

Suggestion:

      assert(strlen(buf) < buflen, "Ran out of buffer room");

and then I think the `len` local is unused.

src/hotspot/os/bsd/os_bsd.cpp line 1524:

> 1522:       len = strlen(buf);
> 1523:       assert(len < buflen, "Ran out of buffer space");
> 1524:       // Add the appropriate library  and JVM variant subdirs

Suggestion:

      // Add the appropriate library and JVM variant subdirs

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PR Review: https://git.openjdk.org/jdk/pull/24310#pullrequestreview-2755056558
PR Review Comment: https://git.openjdk.org/jdk/pull/24310#discussion_r2036313005
PR Review Comment: https://git.openjdk.org/jdk/pull/24310#discussion_r2036315186