RFR: 8292640: C2: Remove unused scratch register usages on x86 [v3]

[Vladimir Ivanov]

> (PR is dependent on #9932.)
> 
> Remove redundant scratch register usages in C2 generated code on x86. 
> 
> Stubs put constants in code cache, so they are RIP-relative addressable from generated code. It allows to save on scratch registers when accessing constants.  
> 
> Testing: hs-tier1 - hs-tier4

Vladimir Ivanov has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains seven commits:

 - Merge branch 'master' into rscratch.redundant
 - redundant temps
 - movptr
 - 8292638: x86: Improve scratch register handling in VM stubs
 - StubRoutines cleanup
 - tabs
 - x86: Improve handling of constants in trigonometric stubs

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Changes: https://git.openjdk.org/jdk/pull/9933/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9933&range=02
  Stats: 406 lines in 5 files changed: 22 ins; 28 del; 356 mod
  Patch: https://git.openjdk.org/jdk/pull/9933.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9933/head:pull/9933

PR: https://git.openjdk.org/jdk/pull/9933