RFR: 8262837: handle split_USE correctly [v3]

[Vladimir Kozlov]

On Wed, 3 Mar 2021 08:40:13 GMT, kuaiwei <github.com+1981974+kuaiwei at openjdk.org> wrote:

>> I look into reg_split.cpp and found a potential issue.
>> Function split_USE usually creates a new spill copy node, but in some cases it just connect def to use and no new node created. But in caller side, they will assume it will create a new node. The code is like:
>> ++
>> maxlrg = split_USE(...)
>> if (!maxlrg) {
>>    return 0;
>> }
>> insidx++;  // Reset iterator to skip USE side split
>> So if no node is created, the iterator index is updated and the next instruction will be skipped.
>> 
>> The change is let split_USE return the new node count, so the caller can update its index and maxlrg.
>
> kuaiwei has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8262837: handle split_USE correctly

Good.
Passed tier1-4 testing.

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Marked as reviewed by kvn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/2791