RFR: 8266746: C1: Replace UnsafeGetRaw with UnsafeGetObject when setting up OSR entry block [v3]

[Yi Yang]

> After JDK-8150921, most Unsafe{Get,Put}Raw intrinsic methods can be replaced by Unsafe{Get,Put}Object.
> 
> There is the only one occurrence where c1 refers UnsafeGetRaw among GraphBuilder::setup_osr_entry_block()
> 
> https://github.com/openjdk/jdk/blob/74fecc070a6462e6a2d061525b53a63de15339f9/src/hotspot/share/c1/c1_GraphBuilder.cpp#L3143-L3157
> 
> We can replace UnsafeGetRaw with UnsafeGetObject when setting up OSR entry block. After that, Unsafe{Get,Put}Raw can be completely removed  because no one refers to them.
> 
> (This patch actually does two things:
> 1. `Replace UnsafeGetRaw with UnsafeGetObject when setting up OSR entry block` This is the only occurrence where c1 refers UnsafeGetRaw
> 2. `Cleanup unused Unsafe{Get,Put}Raw code`
> They are related so I put it together, but I still want to hear your suggestions, I will separate them into two patches if you think it is more reasonable)
> 
> Thanks!
> Yang

Yi Yang has updated the pull request incrementally with one additional commit since the last revision:

  many nit

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3917/files
  - new: https://git.openjdk.java.net/jdk/pull/3917/files/8c239e45..be6b9891

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3917&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3917&range=01-02

  Stats: 14 lines in 3 files changed: 2 ins; 0 del; 12 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3917.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3917/head:pull/3917

PR: https://git.openjdk.java.net/jdk/pull/3917