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

[Ioi Lam]

On 3/31/21 10:22 PM, David Holmes wrote:
> On 1/04/2021 5:05 am, Ioi Lam wrote:
>> On Wed, 31 Mar 2021 12:58:50 GMT, Coleen Phillimore 
>> <coleenp at openjdk.org> wrote:
>>
>>>
>>>> 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.
>
> Sorry but I don't understand how a test involving one flag replaces a 
> chunk of code that validated every flag declaration ??
>

When I did JDK-8243208, I wasn't sure if the VM would actually support 
diagnostic/manageable/experimental flags that were not `product`. So I 
added check_all_flag_declarations() to prevent anyone from adding such a 
flag "casually" without thinking about.

Now that I have added such a flag, and I believe I have tested pretty 
thoroughly (tiers 1-4), I think the VM indeed supports these flags. So 
now I feel it's safe to remove check_all_flag_declarations().

Thanks
- Ioi



> David
> -----
>
>> 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);
>>      }
>>    }
>> }
>>
>> -------------
>>
>> PR: https://git.openjdk.java.net/jdk/pull/3254
>>