RFR: 8256205: Simplify compiler calling convention handling

[Claes Redestad]

On Mon, 16 Nov 2020 18:57:38 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Clean up and simplify some of the calling convention handling:
>> 
>> - Remove Matcher::calling_convention/c_calling_convention and replace select few call sites with direct calls to SharedRuntime
>> - Remove unused is_outgoing args. Since the SPARC removal the is_outgoing has no effect on the calling_convention or return_value methods.
>> - Move in_preserved_stack_slots to SharedRuntime to match out_preserved_stack_slots. 
>> 
>> This has a tiny positive impact by reducing calls and improving inlining (at least gcc has a hard time inlining anything that goes in the .ad files, even when it's defined to the same class), but is mainly a cleanup effort.
>> 
>> Testing: Oracle tier1-2 testing; S390, PPC and ARM32 builds
>
> Nice clean up.

@vnkozlov @neliasso - thank you for reviewing!

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PR: https://git.openjdk.java.net/jdk/pull/1168