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

[Christian Thalinger]

Looks good.  -- Chris

On Sep 4, 2013, at 2:56 AM, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:

> FYI, I've updated [1] with proposed changes.
> 
> Best regards,
> Vladimir Ivanov
> 
> [1] http://cr.openjdk.java.net/~vlivanov/8001107/webrev.04
> 
> On 9/4/13 1:20 AM, Vladimir Kozlov wrote:
>> 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