RFR(XS): 8202425: [s390] C2: Wrong unsigned comparison with 0

Schmidt, Lutz lutz.schmidt at sap.com
Mon Apr 30 14:58:52 UTC 2018

Hi Martin,

your change looks good. (Not a review, I’m not a reviewer).

Thank you for finding and fixing this!


From: hotspot-compiler-dev <hotspot-compiler-dev-bounces at openjdk.java.net> on behalf of "martin.doerr at sap.com" <martin.doerr at sap.com>
Date: Monday, 30. April 2018 at 16:18
To: "'hotspot-compiler-dev at openjdk.java.net'" <hotspot-compiler-dev at openjdk.java.net>
Subject: [CAUTION] RFR(XS): 8202425: [s390] C2: Wrong unsigned comparison with 0


we have observed many errors after JDK-8200303 on s390 which are caused by a wrong node in s390.ad:
compU_reg_imm0. It's used for unsigned comparison with 0, but it's implemented as signed comparison.

We can simply remove this node because we have compU_reg_uimm in place which works correctly (just with a larger encoding).

Please review:

Best regards,

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