RFR: 8014021: TreeMaker.Params behaves inconsistently when the owning method has the same number of parameters as the number of parameter types requested

[Jonathan Gibbons]

On Sat, 18 Feb 2023 01:59:27 GMT, Archie L. Cobbs <duke at openjdk.org> wrote:

> The method `TreeMaker.Params` has what appears to be strange behavior: normally it creates parameters of the types passed in. However, if the given owner is a method, and the method happens to have the same number of parameters as the number of parameters requested, then the types of the owner method's parameters are used instead. This is weird and confusing.
> 
> What's really going on is that a method owner is _always_ being passed in, and when that method has parameters defined, there are _always_ exactly as many of them as there are types provided.
> 
> So what this method is really doing is just reusing the same symbols for the methods parameters if the method has them defined, otherwise creating the same number of placeholder parameters `x0`, `x1`, `x2`, etc.
> 
> This patch refactors this method and clarifies its usage to eliminate the confusion.

This doesn't seem to address the concern expressed in the JBS issue about it being a weird dual use. It just seems to be a partial cleanup in the same area.

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PR: https://git.openjdk.org/jdk/pull/12627