Request for review (S): CR 6889740 - G1: OpenDS fails with "unhandled exception in compiled code"
Thomas.Rodriguez at Sun.COM
Thu Oct 29 13:52:42 PDT 2009
On Oct 28, 2009, at 1:58 PM, john cuthbertson - Sun Microsystems wrote:
> Hi Everyone,
> I've tweaked the change based on feedback from Christian and Tom.
> The new webrev can be found here:
> On 10/27/09 14:51, john cuthbertson - Sun Microsystems wrote:
>> Hi Everyone,
>> Can I have a couple of volunteers to review the proposed fix for
>> this bug? The webrev can be found at http://cr.openjdk.java.net/~johnc/6889740/webrev.0/
>> The issue is that bad code was being generated for the store
>> operation in the null case of the aastore bytecode template. The
>> bad code was caused by there being only one version of the
>> store_heap_oop routine that took a Register as the second argument.
>> When the calling code passed in NULL_WORD (0) to this routine the
>> value was used as a Register encoding and converted to Register(0),
>> which is rax. Thus the generated store was "mov (dst), $rax"
>> instead of "mov (dst), $0x0". This is normally not a problem as the
>> preceding code in the template fetches the value to be stored into
>> rax. When the G1 pre-barrier code calls the runtime, however, the
>> value in rax can be overwritten and the heap can become corrupted.
>> Testing: OpenDS, jprt, refworkload, and the GC test suite.
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