Preliminary RFR (L): 8001107: @Stable annotation for constant folding of lazily evaluated variables

[Vladimir Kozlov]

On 9/3/13 2:04 PM, Vladimir Ivanov wrote:
> John,
>
> I'm fine with both options (add an assert or use
> element_value(index).as_char() in product).
>
> Vladimir K., what do you prefer?

assert

Vladimir K

>
> Best regards,
> Vladimir Ivanov
>
> On 9/3/13 10:40 AM, John Rose wrote:
>> On Aug 29, 2013, at 4:57 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com
>> <mailto:vladimir.kozlov at oracle.com>> wrote:
>>
>>>>> ciTypeArray.cpp: why we need these changes?
>>>> I consider this as a cleanup. element_value(index).as_char() performs
>>>> additional checks and it looks better (IMO, of course :-) ) than
>>>> get_typeArrayOop()->char_at(index).
>>>
>>> But element_value() is much more expensive! I don't like this change.
>>
>> The old char_at function works fine, but I think it needs an assert that
>> the array being referenced is truly a char[] array.  The more expensive
>> element_value function performs this check, so it is safer.  It is also
>> helpful to prove (at least via an assert) that element_value is a true
>> extension of char_at.
>>
>> If we don't like making char_at slightly more expensive (it doesn't make
>> much difference!) then I suggest putting the call to element_value into
>> the #ifdef ASSERT, as follows:
>>
>>      assert(index >= 0 && index < length(), "out of range");
>> !   jchar c = get_typeArrayOop()->char_at(index);
>> ! #ifdef ASSERT
>> !   jchar d = element_value(index).as_char();
>> !   assert(c == d, "");
>> ! #endif //ASSERT
>> !   return c;
>>    }
>>
>> — John