Bug ID: JDK-8157726 VarHandles/Unsafe should support sub-word atomic ops

Type: Sub-task
Component: core-libs
Sub-Component: java.lang.invoke
Affected Version: 9

Priority: P3
Status: Resolved
Resolution: Fixed

Submitted: 2016-05-24
Updated: 2019-01-23
Resolved: 2016-06-15

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JDK 9
9 b127Fixed

See the discussion here:
  http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-May/041369.html
  http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-May/041382.html

This needs new entry points in Unsafe, compiler support and intrinsics. Also, a sensible fallback strategy for platforms lacking sub-word atomic ops.

Rebased: http://cr.openjdk.java.net/~shade/8157726/webrev.hs.04/ http://cr.openjdk.java.net/~shade/8157726/webrev.jdk.04/
09-06-2016
CCC approved
01-06-2016
RFR: http://mail.openjdk.java.net/pipermail/jdk9-dev/2016-May/004365.html
27-05-2016
+ x86_32 intrinsics: http://cr.openjdk.java.net/~shade/8157726/webrev.hs.03/ http://cr.openjdk.java.net/~shade/8157726/webrev.jdk.03/
26-05-2016
+ test updates for byte order, + tests pass on big-endian platforms, + spec update, + cleanups: http://cr.openjdk.java.net/~shade/8157726/webrev.hs.02/ http://cr.openjdk.java.net/~shade/8157726/webrev.jdk.02/
26-05-2016
+ VarHandles bindings: http://cr.openjdk.java.net/~shade/8157726/webrev.hs.01/ http://cr.openjdk.java.net/~shade/8157726/webrev.jdk.01/
25-05-2016
Preliminary webrevs (Unsafe support for {byte,short} x {CAS, weakCAS, CAE, getAndAdd, getAndSet} + their x86_64 intrinsics): http://cr.openjdk.java.net/~shade/8157726/webrev.hs.00/ http://cr.openjdk.java.net/~shade/8157726/webrev.jdk.00/
24-05-2016

Blocks :	JDK-8159531 - Investigate SPARC intrinsics for VarHandle/Unsafe sub-word atomic ops
Duplicate :	JDK-8157254 - Unsafe CompareAndSwap loops should use weak*Volatile CAS
Relates :	JDK-8160360 - Mismatched field loads are folded in LoadNode::Value
Relates :	JDK-8164103 - C2: Broken cmpxchgb encoding on x86
Relates :	JDK-8158039 - VarHandle float/double field/array access should support CAS/set/add atomics
Relates :	JDK-8046183 - JEP 193: Variable Handles