RFR: 8302814: Delete unused CountLoopEnd instruct with CmpX [v6]

[SUN Guoyun]

> CountLoopEnd only for T_int, therefore the following instructs in riscv.ad are useless and should be deleted.
> 
> CountedLoopEnd cmp (CmpU op1 op2)
> CountedLoopEnd cmp (CmpP op1 op2)
> CountedLoopEnd cmp (CmpN op1 op2)
> CountedLoopEnd cmp (CmpF op1 op2)
> CountedLoopEnd cmp (CmpD op1 op2)
> 
> and CountedLoopEnd with CmpU on x86*.ad, aarch64.ad ar useless also.
> 
> Please help review it.
> 
> Thanks.

SUN Guoyun 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 seven additional commits since the last revision:

 - Merge branch 'openjdk:master' into 8302814
 - 8302814: Delete unused CountLoopEnd instruct with CmpX
 - 8302814: Delete unused CountLoopEnd instruct with CmpX
 - 8302814: Delete unused CountLoopEnd instruct with CmpX
 - Merge branch 'openjdk:master' into 8302814
 - Merge branch 'openjdk:master' into 8302814
 - 8302814: Delete unused CountLoopEnd instruct with CmpX

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/12648/files
  - new: https://git.openjdk.org/jdk/pull/12648/files/fefb9122..0652b11c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12648&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12648&range=04-05

  Stats: 360496 lines in 2711 files changed: 216340 ins; 121512 del; 22644 mod
  Patch: https://git.openjdk.org/jdk/pull/12648.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/12648/head:pull/12648

PR: https://git.openjdk.org/jdk/pull/12648