(original) (raw)

+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@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