RFR: 8253734: C2: Optimize Move nodes [v2]

[Vladimir Ivanov]

> Introduce the following transformations for Move nodes: 
> 1. `MoveI2F (MoveF2I x) => x`
> 
> 1. `MoveI2F (LoadI mem) => LoadF mem` 
> 
> 1. `StoreI mem (MoveF2I x) => StoreF mem x` 
> 
> (The same applies to MoveL2D/MoveD2L.)
> 
> №1 eliminates redundant operations and №2/№3 avoid reg-to-reg moves in generated code:
> 0x000000010d09964c:   vmovss 0x20(%rsi),%xmm1
> 0x000000010d099651:   vmovd  %xmm1,%eax                   ;*invokestatic floatToRawIntBits
> vs
> 0x0000000110c5a6cc:   mov    0x20(%rsi),%eax              ;*invokestatic floatToRawIntBits
>  
> 
> (№2 and №3 are performed late (after loop opts are over) to avoid high-level optimizations passes to handle newly introduced mismatched accesses.)
> 
> Testing: tier1-5.

Vladimir Ivanov has updated the pull request incrementally with one additional commit since the last revision:

  Address review comments from Tobias.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/826/files
  - new: https://git.openjdk.java.net/jdk/pull/826/files/567c4fb7..878d44bf

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=826&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=826&range=00-01

  Stats: 78 lines in 4 files changed: 16 ins; 26 del; 36 mod
  Patch: https://git.openjdk.java.net/jdk/pull/826.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/826/head:pull/826

PR: https://git.openjdk.java.net/jdk/pull/826