Request for sponsor: 4421494 infinite loop while parsing double literal

[Joseph D. Darcy]

Dmitry Nadezhin wrote:
> Hello Joe,
>
> Thank you for the sponsorship of the bug 4421494.
>
> I can also prepare a fix for another related bug 4396272
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4396272
>
> The bug 4396272 is blinking because it occurs only when HotSpot 
> chooses double value set and it doesn't occur
> with double-extended-exponent value set.
> The suggested fix will be in FloatingDecimal too, though in other line.
>
> What is more convenient to you
> a) if I combine both fixes of 4421494 and 4396272 in a single 
> changeset now;
> b) if I postpone submitting of the fix 4396272 until 4421494 is in the 
> JDK
> ?

If the first fix is just a one-liner, combining the two fixes is easier 
overall.

Cheers,

-Joe

>  -Dima
>> Dmitry Nadezhin wrote:
>>> http://bugs.sun.com/view_bug.do?bug_id=4421494
>>> https://bugs.openjdk.java.net/show_bug.cgi?id=100119
>>>
>>> Summary: This old bug report says that Double.parseDouble(s) hangs 
>>> for decimal strings
>>> in range (Double.MIN_NORMAL-0.5*Double.MIN_VALUE,Double.MIN), and 
>>> returns
>>> incorrect result for decimal string 
>>> Double.MIN_NORMAL-0.5*Double.MIN_VALUE.
>>>
>>> This is because current code in FloatingDecimal.doubleValue() 
>>> incorrectly
>>> defines the condition when nextDown(dValue) - dValue == 
>>> -0.5*ulp(dValue). The
>>> current code considers that these are all numbers 2^n which are 
>>> represented as
>>> normal doubles, and nexDown(dValue) - dValue == -1.0*ulp(dValue) for 
>>> other
>>> doubles (subnormal or not 2-powers).
>>> However, this is not correct for dValue == Double.MIN_VALUE, because
>>> nextDown(Double.MIN_NORMAL) - Double.MIN_NORMAL == 
>>> -1.0*ulp(Double.MIN_NORMAL).
>>>
>>> The suggested change
>>> -                    if ( (bigIntNBits == 1) && (bigIntExp > 
>>> -expBias) ){
>>> +                    if ( (bigIntNBits == 1) && (bigIntExp > 
>>> -expBias+1) ){
>>> redefines the condition so that dValue == Double.MIN_NORMAL doesn't 
>>> satisfy it.
>>>
>>> -Dima
>>
>> Hello.
>>
>> Thank you for the proposed fix; that certainly sounds like a 
>> plausible cause of the problem.
>>
>> I'm a bit swamped now, but I'll try to look at verifying the fix and 
>> sponsoring getting it back into the JDK within the next few weeks.
>>
>> -Joe
>