RFR: 8264285: Clean the modification of ccstr JVM flags [v2]

[Ioi Lam]

On Wed, 31 Mar 2021 12:58:50 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   relax flag attributions (ala JDK-7123237)
>
> src/hotspot/share/runtime/flags/debug_globals.hpp line 38:
> 
>> 36: // have any MANAGEABLE flags of the ccstr type, but we really need to
>> 37: // make sure the implementation is correct (in terms of memory allocation)
>> 38: // just in case someone may add such a flag in the future.
> 
> Could you have just added a develop flag to the manageable flags instead?

I had to use a `product` flag due to the following code, which should have been removed as part of [JDK-8243208](https://bugs.openjdk.java.net/browse/JDK-8243208), but I was afraid to do so because I didn't have a test case. I.e., all of our diagnostic/manageable/experimental flags were `product` flags.

With this PR, now I have a test case -- I changed `DummyManageableStringFlag` to a `notproduct` flag, and removed the following code. I am re-running tiers1-4 now.

void JVMFlag::check_all_flag_declarations() {
  for (JVMFlag* current = &flagTable[0]; current->_name != NULL; current++) {
    int flags = static_cast<int>(current->_flags);
    // Backwards compatibility. This will be relaxed/removed in JDK-7123237.
    int mask = JVMFlag::KIND_DIAGNOSTIC | JVMFlag::KIND_MANAGEABLE | JVMFlag::KIND_EXPERIMENTAL;
    if ((flags & mask) != 0) {
      assert((flags & mask) == JVMFlag::KIND_DIAGNOSTIC ||
             (flags & mask) == JVMFlag::KIND_MANAGEABLE ||
             (flags & mask) == JVMFlag::KIND_EXPERIMENTAL,
             "%s can be declared with at most one of "
             "DIAGNOSTIC, MANAGEABLE or EXPERIMENTAL", current->_name);
      assert((flags & KIND_NOT_PRODUCT) == 0 &&
             (flags & KIND_DEVELOP) == 0,
             "%s has an optional DIAGNOSTIC, MANAGEABLE or EXPERIMENTAL "
             "attribute; it must be declared as a product flag", current->_name);
    }
  }
}

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PR: https://git.openjdk.java.net/jdk/pull/3254