APAR status
Closed as program error.
Error description
Error Message: The user will report an incorrect floating point math result when running on an x86 CPU which supports the AVX instruction set extensions. The bad result will be generated by a three operand AVX floating point instruction (usually an add or subtract). . Stack Trace: N/A . The problem can only occur on x86 hardware and only when running Java 8 SR5 FP18 through FP26 (8.0.5.18 - 8.0.5.26) when run on x86 machines which support the AVX instruction set extensions.
Local fix
The problem is more likely to occur in cold compiles since some of the opportunities for the bug to occur are eliminated by higher optimization strategies. Use of -Xjit:dontDowngradeToCold may help reduce the frequency of errors but will not eliminate it. There is no workaround guaranteed to fully prevent the error
Problem summary
In some circumstances the JIT code generator may incorrectly reload a value from memory rather than reusing a previously loaded result which can lead to different data being read and an incorrect result.
Problem conclusion
The code generator was fixed to ensure that loads were not repeated incorrectly - the generated code sequence will now reuse the previously loaded value correctly. . This APAR will be fixed in the following Java Releases: 8 SR5 FP27 (8.0.5.27) . Contact your IBM Product's Service Team for these Service Refreshes and Fix Packs. For those running stand-alone, information about the available Service Refreshes and Fix Packs can be found at: https://www.ibm.com/developerworks/java/jdk/
Temporary fix
Comments
APAR Information
APAR number
IJ12156
Reported component name
JIT
Reported component ID
620700124
Reported release
130
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2018-12-13
Closed date
2018-12-13
Last modified date
2018-12-13
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
JIT
Fixed component ID
620700124
Applicable component levels
[{"Business Unit":{"code":"BU048","label":"IBM Software"},"Product":{"code":"SSC9HBA","label":"Just In Time (JIT) Compiler"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"130","Edition":"","Line of Business":{"code":"","label":""}}]
Document Information
Modified date:
13 December 2018