RFR: 8325681: C2 inliner rejects to inline a deeper callee because the methoddata of caller is immature. [v2]

[Xin Liu]

> This patch uses the methoddata of a method no matter it is mature or not to initialize `ciCallProfile`. Previously, C2 drops premature methoddata and leaves _count field of ciCallProfile -1. This leads C2 refuses to inline the callsite because its frequency is too low(-1 < MinInlineFrequencyRatio).  
> 
> In the given example, we observes that baz was not inlined because of 'low call site frequency'.  This is wrong because its real frequency is 10% > MinInlineFrequencyRatio. 
> 
> 
> 60 13 b 4 UnderProfiledSubprocedure::foo (9 bytes)
>                               @ 5 UnderProfiledSubprocedure::bar (6 bytes) inline (hot)
>                                 @ 1 UnderProfiledSubprocedure::baz (19 bytes) failed to inline: low call site frequency

Xin Liu has updated the pull request incrementally with one additional commit since the last revision:

  Update the comment.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17957/files
  - new: https://git.openjdk.org/jdk/pull/17957/files/f739939f..c16be286

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17957&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17957&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17957.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17957/head:pull/17957

PR: https://git.openjdk.org/jdk/pull/17957