RFR(S): 8196296: Lucene test crashes C2 compilation

[Uwe Schindler]

Ah sorry, I see the test.

Uwe

Am January 26, 2018 10:50:11 PM UTC schrieb Uwe Schindler <uschindler at apache.org>:
>Hi Roland,
>
>Many thanks. Did you figure out which code part in Lucene or ICU4J
>caused this?
>
>I don't see a test case in the patch.
>
>Uwe
>
>Am January 26, 2018 10:21:17 PM UTC schrieb Roland Westrelin
><rwestrel at redhat.com>:
>>
>>http://cr.openjdk.java.net/~roland/8196296/webrev.00/
>>
>>C2 attempts to merge 2 back to back ifs with the same condition:
>>
>>if (condition) {
>>
>>} else {
>>
>>}
>>
>>if (condition) {
>>
>>but the second if is a counted loop end test. This causes the counted
>>loop to not keep a canonical shape. With debug builds, loop strip
>>mining
>>verification code then causes the test to crash. With product builds,
>>the logic that finalizes the outer strip mined loop bails out but
>>leaves
>>the outer loop. The test of the outer loop is turned into an If with a
>>constant input that's not optimized out. In the reported failure,
>>Matcher code then breaks because the If has a non Cmp input. I fixed
>>the logic in OuterStripMinedLoopNode::adjust_strip_mined_loop() so
>that
>>when it bails out, it causes the outer loop to go away and prevent 2
>>back to back ifs to merge if the second one is a counted loop end.
>>
>>Roland.
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