RFR: 8255553: [PPC64] Introduce and use setbc and setnbc P10 instructions [v4]

[Ziviani]

> - setbc RT,BI: sets RT to 1 if CR(BI) is 1, otherwise 0.
> - setnbc RT,BI: sets RT to -1 if CR(BI) is 1, otherwise 0.
> Ref: PowerISA 3.1, page 129.
> 
> These instructions are particularly interesting to improve the following
> pattern `(src1<src2)? -1: ((src1>src2)? 1: 0)`, which can be found in
> `instruct cmpL3_reg_reg_ExEx()@ppc.ad`, by removing its branches.
> 
> Long.toString, that generate such pattern in getChars, has showed a
> good performance gain by using these new instructions.
> 
> Example:
> for (int i = 0; i < 200_000; i++)
>   res = Long.toString((long)i);
> 
> java -Xcomp -XX:CompileThreshold=1 -XX:-TieredCompilation TestToString
> 
> Without setbc (average): 0.1178 seconds
> With setbc (average): 0.0396 seconds

Ziviani has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains one additional commit since the last revision:

  8255553: [PPC64] Introduce and use setbc and setnbc P10 instructions
  
  - setbc RT,BI: sets RT to 1 if CR(BI) is 1, otherwise 0.
  - setnbc RT,BI: sets RT to -1 if CR(BI) is 1, otherwise 0.
  Ref: PowerISA 3.1, page 129.
  
  These instructions are particularly interesting to improve the following
  pattern `(src1<src2)? -1: ((src1>src2)? 1: 0)`, which can be found in
  `instruct cmpL3_reg_reg_ExEx()@ppc.ad`, by removing its branches.
  
  Long.toString, that generate such pattern in getChars, has showed a
  good performance gain by using these new instructions.
  
  Example:
  for (int i = 0; i < 200_000; i++)
    res = Long.toString((long)i);
  
  java -Xcomp -XX:CompileThreshold=1 -XX:-TieredCompilation TestToString
  
  Without setbc (average): 0.1178 seconds
  With setbc (average): 0.0396 seconds

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/907/files
  - new: https://git.openjdk.java.net/jdk/pull/907/files/41502730..0af02057

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=907&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=907&range=02-03

  Stats: 8084 lines in 281 files changed: 4806 ins; 2000 del; 1278 mod
  Patch: https://git.openjdk.java.net/jdk/pull/907.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/907/head:pull/907

PR: https://git.openjdk.java.net/jdk/pull/907