RFR: 8281429: PhiNode::Value() is too conservative for tripcount of CountedLoop [v4]

[Christian Hagedorn]

On Tue, 22 Mar 2022 12:53:24 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> src/hotspot/share/opto/cfgnode.cpp line 1129:
>> 
>>> 1127:                   julong diff = (uhi - ulo - 1) / (-stride_t->lo_as_long()) * (-stride_t->lo_as_long());
>>> 1128:                   julong ufirst = hi->lo_as_long() - diff;
>>> 1129:                   first = reinterpret_cast<jlong &>(ufirst);
>> 
>> Could we also use a `static_cast` here and further down instead?
>
> Thanks for looking at this.
> I'm not sure. I modeled this code on java_add/java_substract etc.

I thought that just for a numeric conversion, one could use `static_cast` as `reinterpret_cast` operates on pointers or references. But I'm not entirely sure what the convention should be. I guess both should work fine.

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PR: https://git.openjdk.java.net/jdk/pull/7823