[14] RFR(S): 8234616: assert(0 <= i && i < _len) failed: illegal index in PhaseMacroExpand::expand_macro_nodes()

[Vladimir Kozlov]

+1

Vladimir K

On 12/3/19 7:16 AM, Vladimir Ivanov wrote:
> 
>> http://cr.openjdk.java.net/~thartmann/8234616/webrev.00/
> 
> Looks good.
> 
> Best regards,
> Vladimir Ivanov
> 
>>
>> We assert in PhaseMacroExpand::expand_macro_nodes() when accessing the macro_node array because
>> 'macro_idx' is out of the upper bound:
>> https://hg.openjdk.java.net/jdk/jdk/file/43c4fb8ba96b/src/hotspot/share/opto/macro.cpp#l2591
>>
>> The problem is that in the previous iteration, we hit the following code path which removes an
>> unreachable macro node but does not decrement 'macro_idx':
>> https://hg.openjdk.java.net/jdk/jdk/file/43c4fb8ba96b/src/hotspot/share/opto/macro.cpp#l2594
>>
>> The problem was introduced in JDK 14 by the fix for JDK-8227384:
>> https://hg.openjdk.java.net/jdk/jdk/rev/43c4fb8ba96b#l3.25
>>
>> I've changed the loop to a for-loop to make sure the index is always decremented and also
>> strengthened the asserts. I was not able to create a regression test but the issue reproduces
>> intermittently with Lucene.
>>
>> Thanks,
>> Tobias
>>