RFR: 8319429: Resetting MXCSR flags degrades ecore [v2]

[Volodymyr Paprotski]

> Improves vector rounding on ECore about 10x
> 
> (BEFORE) FpRoundingBenchmark.test_round_float        2048  thrpt    3  40.912 ± 0.044  ops/ms
> (AFTER ) FpRoundingBenchmark.test_round_float        2048  thrpt    3  431.682 ± 0.727  ops/ms

Volodymyr Paprotski has updated the pull request incrementally with one additional commit since the last revision:

  move option to x86-specific section

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16504/files
  - new: https://git.openjdk.org/jdk/pull/16504/files/010a993f..f4c8c36e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16504&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16504&range=00-01

  Stats: 7 lines in 2 files changed: 4 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16504.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16504/head:pull/16504

PR: https://git.openjdk.org/jdk/pull/16504