RFR: 8293416: ZGC: Set mark bit with unconditional atomic ops [v2]

[hev]

> **Summary**
> Support to set ZGC mark bit with unconditional atomic ops.
> 
> **Motivation**
> ZGC currently modify mark-bitmap by a conditional atomic operation (cmpxchg). This way is not optimal, which will retry the loop when cmpxchg fails.
> 
> **Description**
> First, This patch-set add an new unconditional atomic operation: Atomic::fetch_and_or, which is implemented in different ways for different CPU architectures:
> 
> * Exclusive access: Non-nested loop
> 
> 
> retry:
>   ll old_val, addr
>   or new_val, old_val, set_val
>   sc new_val, addr
>   beq retry
> 
> 
> * Atomic access: One instruction
> 
> 
> ldset old_val, set_val, addr
> 
> 
> * Generic: Fallback to cmpxchg or use c++ __atomic_fetch_or
> 
> **Testing**
> * jtreg tests
> * benchmark tests

hev has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  8293416: ZGC: Set mark bit with unconditional atomic ops

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10182/files
  - new: https://git.openjdk.org/jdk/pull/10182/files/5e580f44..016ee1f1

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10182&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10182&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/10182.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10182/head:pull/10182

PR: https://git.openjdk.org/jdk/pull/10182