RFR: 8370481: C2 SuperWord: Long/Integer.compareUnsigned return wrong value in SLP [v3]

[Hamlin Li]

On Thu, 23 Oct 2025 14:35:03 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> src/hotspot/share/opto/superword.cpp line 1752:
>> 
>>> 1750:   case Op_CmpUL:
>>> 1751:   case Op_CmpU3:
>>> 1752:   case Op_CmpUL3:
>> 
>> Do these really ever survive to here? I thought they should all be turned into other ops? Do you have an example?
>
> If these never come through here, then just let them go into the default case.

will fix.

>> src/hotspot/share/opto/superword.cpp line 1760:
>> 
>>> 1758:   case Op_CmpP:
>>> 1759:   case Op_CmpD3:
>>> 1760:   case Op_CmpF3:
>> 
>> These would probably have the same issue as the regular `CmpF/CmpD`, no? So are we sure we can "allow-list" them here?
>
> If these never come through here, then just let them go into the default case.

will fix.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27942#discussion_r2455463230
PR Review Comment: https://git.openjdk.org/jdk/pull/27942#discussion_r2455464693