Array not zeroed on creation

[Krystal Mo]

+1 with Nils.

Running the test case with -XX:-OptimizeFill works around the problem; 
running again, this time with -XX:+TraceOptimizeFill, shows:

$ ~/testjdk/hotspot-comp/bin/java -XX:-TieredCompilation 
-XX:+TraceOptimizeFill -XX:+PrintCompilation Test7196857
     194    1             java.util.Arrays::fill (21 bytes)
     195    1 %           Test7196857::main @ 89 (162 bytes)
fill intrinsic for:
  111    StoreI    ===  138  131  109  11  [[ 124  131 ]] 
@int[int:>=0]:exact+any *, idx=5;  Memory: 
@int[int:>=0]:NotNull:exact+any *, idx=5; !jvms: Arrays::fill @ bci:13
fill intrinsic for:
  463    StoreI    ===  537  442  461  20  [[ 509  442 ]] 
@int[int:>=0]:exact+any *, idx=6;  Memory: 
@int[int:10]:NotNull:exact+any *, idx=6; !orig=[500],488,[486],[111] 
!jvms: Arrays::fill @ bci:13 Test7196857::main @ bci:83
Eliminated zeroing in allocation
not fill intrinsic candidate: variant store value
     219    1 %           Test7196857::main @ -2 (162 bytes)   made not 
entrant
Exception in thread "main" java.lang.RuntimeException: Array just after 
allocation: [-1163019586, -1163019586, -1163019586, -1163019586, 
-1163019586, -1163019586, -1163019586, -1163019586, -1163019586, 
-1163019586]
     at Test7196857.main(Test7196857.java:11)

Notice "Eliminated zeroing in allocation", which is caused by the 
missing check that Nils mentioned.

- Kris

On 09/07/2012 10:11 PM, Nils Eliasson wrote:
> The bug reproduces with a fill or a corresponding zeroing for loop. 
> But not without. So the bug is that there should be a check of uses 
> between the allocation and the fill (or that the check is incomplete).
>
> //Nils
>
> Vitaly Davidovich skrev 2012-09-07 15:24:
>>
>> Dan,
>>
>> I've cc'd compiler dev and removed hotspot dev as this looks like a 
>> compiler issue.  Hope you don't mind.
>>
>> My hunch is that the Arrays.fill() is tripping this up - is it 
>> reproducable if fill() is removed?
>>
>> Sent from my phone
>>
>> On Sep 7, 2012 8:39 AM, "Dan Hicks" <danhicks at fastmail.fm 
>> <mailto:danhicks at fastmail.fm>> wrote:
>>
>>     This bug has come to my attention:
>>     http://stackoverflow.com/questions/12317668/java-int-array-initializes-with-nonzero-elements
>>
>>     Basically there is a reproducible (by several people) situation
>>     where a new int array is not zeroed.  The author reports the
>>     error is reproducible on HotSpot 64-bit server VM, Java version
>>     from 1.7.0_04 to 1.7.0_10 on Gentoo Linux, Debian Linux (both
>>     kernel 3.0 version) and MacOS Lion.  (Not tested on 32-bit or
>>     Windows.)
>>
>>     Reportedly bug7196857 has been filed with Oracle.
>>
>>     -- 
>>     Dan Hicks
>>     Nothing makes us so lonely as our secrets.  --Paul Tournier
>>
>

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