RFR: 8255026: C2: Miscellaneous cleanups in Compile and PhaseIdealLoop code

[Claes Redestad]

On Mon, 19 Oct 2020 19:55:58 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> Miscellaneous cleanups in Compile and PhaseIdealLoop code.
> 
> Compile:
> 
> - inline node lists
> 
> - remove empty Compile::register_library_intrinsics()
> 
> - introduce `Compile::remove_useless_nodes(GrowableArray<Node*>& node_list, Unique_Node_List& useful)`
> 
> 
> PhaseIdealLoop:
> 
> - unify logging and IGVN logic
> 
> - refactor logging code
> 
> Testing: tier1 - tier5

Marked as reviewed by redestad (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/749