RFR: JDK-8302989: Add missing INCLUDE_CDS checks [v3]

[David Holmes]

On Thu, 2 Mar 2023 16:27:32 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> The cds only coding in hotspot is usually guarded with the INCLUDE_CDS macro so that it can be removed at compile time in case the correct configure flags are set.
>> However at some places INCLUDE_CDS is missing and should be added.
>> 
>> One question - should (additionally to the UseSharedSpaces code section)  the DumpSharedSpaces code sections be guarded as well with INCLUDE_CDS macros ?
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   adjust some cds related vars

src/hotspot/share/runtime/arguments.cpp line 1460:

> 1458: #if INCLUDE_CDS
> 1459:     UseSharedSpaces = false;
> 1460: #endif

This doesn't make sense - the entire `no_shared_spaces` method is only meaningful on a JVM with CDS. Otherwise `-Xshare:on` should immediately be rejected. ??

src/hotspot/share/runtime/arguments.cpp line 2675:

> 2673:       xshare_auto_cmd_line = true;
> 2674:     // -Xshare:off
> 2675:     } else if (match_option(option, "-Xshare:off")) {

These flags should all immediately be rejected if used in a non-CDS build. Yes this is pre-existing but it now looks totally broken with the new changes. There should be something like:

#ifndef INCLUDE_CDS
} else if (match_option(option, "-Xshare")) {  // or whatever we need to match the prefix only
  warning("Option %s is not supported in this VM", option);
#else 
// process flags as usual
#endif

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PR: https://git.openjdk.org/jdk/pull/12691