RFR: 8303970: C2 can not merge homogeneous adjacent two If [v3]

[Cesar Soares Lucas]

On Mon, 20 Mar 2023 02:46:51 GMT, Yi Yang <yyang at openjdk.org> wrote:

>> src/hotspot/share/opto/subnode.cpp line 1488:
>> 
>>> 1486: 
>>> 1487: static bool is_arithmetic_cmp(Node* cmp) {
>>> 1488:   if (!cmp->is_Cmp()) {
>> 
>> Perhaps just merge this if with the next one.
>
> Hi Cesar, I receive feedback from Roland in #13039 that suggested extending identical_backtoback_ifs instead of adding Ideal for BoolNode and CmpNode. 
> 
> Before making any modifications based on your review comment, I would first like to reach a consensus on whether we should add idealization for bool and cmp or extend identical_backtoback_ifs. Do you have any comments in this regard? Perhaps @TobiHartmann and @merykitty  could also chime in.

I was unaware of the other PR. Please ignore my comments if the other PR covers this work.

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PR: https://git.openjdk.org/jdk/pull/12978