8373633: C2: Use interface receiver type to improve CHA decisions

[iwanowww]

Strength-reducing an interface call to a virtual call for interfaces with
unique implementors can use receiver type information to narrow the context.

C2 tracks interface types and receiver type information can be used to reveal
an interface with a unique implementor which can't be derived from the call
site itself.

Since C2 effectively accumulates a union interface type from multiple subtype checks, iterating over individual components of a type may reveal a candidate for a strength-reduction. The only prerequisite is that a candidate has to be a subtype of the declared interface.

Testing: hs-tier1 - hs-tier5

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Issue

• JDK-8373633: C2: Use interface receiver type to improve CHA decisions (Enhancement - P4)

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[mlbridge]

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[rwestrel]

Is there no benefit to passing receiver_type here?