JDK-8029101 : PPC64 (part 211): ordering of Independent Reads of Independent Writes
  • Type: Bug
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: port-stage-ppc-aix
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • CPU: ppc
  • Submitted: 2013-11-25
  • Updated: 2017-01-25
  • Resolved: 2014-01-22
The Version table provides details related to the release that this issue/RFE will be addressed.

Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.

To download the current JDK release, click here.
JDK 8 JDK 9 Other
8u20Fixed 9Fixed port-stage-ppc-aixFixed
Related Reports
Blocks :  
Relates :  
Implementation of memory ordering on PPC for volatile/unsafe accesses.
This supports ordering of "Independent Reads of Independent Writes"
as tested by VolatileIRIWTest of the torture test suite:

 Example: volatile x=0, y=0
_________    __________    __________    __________
 | Thread 0 |  | Thread 1 |  | Thread 2 |  | Thread 3 |

   write(x=1)    read(x)       write(y=1)    read(y)
                 read(y)                     read(x)

 Disallowed:     x=1, y=0                    y=1, x=0

Solution: This example requires multiple-copy-atomicity. This is only
assured by the sync instruction and if it is executed in the thread
doing the load. Thus we implement volatile read as sync-load-acquire
and omit the sync/MemBarVolatile after the volatile store, as
MemBarVolatile happens to be implemented by sync.

This addresses a similar issue as fix "8012144: multiple SIGSEGVs 
fails on staxf" for taskqueue.hpp.

Further this change contains a fix that assures that volatile fields
written in constructors are visible before the reference gets


This is preparation for PPC64 integration: http://openjdk.java.net/jeps/175
This and following ppc64 changes will go into staging repository first and tested there: http://hg.openjdk.java.net/ppc-aix-port/stage/