[aarch64-port-dev ] RFR(S): 8239914: AArch64: Combine add/sub with comparison against zero

[Pengfei Li]

Hi Nick,

> I couldn't reproduce this on the latest jdk/jdk, only with your patch. I think
> the problem is with the cmp*_sub_zero match rules. (a - b) > 0 !== a > b if a -
> b overflows because Java requires the result to wrap around which changes
> the sign.

You are right. That's something wrong with my remote environment before. Sorry about that.

> I think it's ok to update the patch when you come back.

Indeed, my (a + b > 0) has the same overflow issue. And I can produce an incorrect arithmetic result in another case. Hence, my patch has no value and I should abandon it.

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Thanks,
Pengfei