RFR: 8256730: Code that uses Object.checkIndex() range checks doesn't optimize well [v2]

[Roland Westrelin]

On Fri, 20 Nov 2020 15:26:11 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> src/hotspot/share/opto/castnode.cpp line 269:
>> 
>>> 267:                               _carry_dependency, _range_check_dependency);
>>> 268:     cx->set_req(0, in(0));
>>> 269:     cx = phase->transform(cx);
>> 
>> Hi Roland, have you tested that these calls to `transform()` do not create an explosion of recursive `Ideal()` calls in the face of long AddI chains (see https://github.com/openjdk/jdk/pull/727).
>
> I wondered about that but had no issue during testing. Let me see if I can change your test case to have recursive Ideal() calls.

I managed to reproduce a similar issue by tweaking your test cases. I just pushed the new test cases + a change that mirrors your fix.

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PR: https://git.openjdk.java.net/jdk/pull/1342