JRuby

Powering operation of Integer sometimes gets a wrong calculation when 1.9 mode.

Details

  • Type: Bug Bug
  • Status: Closed Closed
  • Priority: Critical Critical
  • Resolution: Fixed
  • Affects Version/s: JRuby 1.6.5
  • Fix Version/s: JRuby 1.6.6, JRuby 1.7.0.pre1
  • Component/s: Core Classes/Modules
  • Labels:
    None
  • Environment:
    jruby 1.6.5 (ruby-1.8.7-p330) (2011-10-25 9dcd388) (Java HotSpot(TM) 64-Bit Server VM 1.6.0_23) [Windows 7-amd64-java]
  • Number of attachments :
    0

Description

ex)
jruby --1.9 -e "p 1539948653 ** 2"
-> 4561929911295338257 (wrong)

jruby --1.9 -e "p 1539948653 * 1539948653"
-> 2371441853876514409 (correct)

Activity

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Hiro Asari added a comment - - edited

This is a rather peculiar problem.

Note https://github.com/jruby/jruby/blob/81cd13e2fe6ee2f87b769851aeefedb626091e96/src/org/jruby/util/Numeric.java#L476

Under some circumstances, this test evaluates to false unexpectedly (because x*x overflows the 'long' range and ends up in just the right range) and we return a wrong value. (The smallest integer for which this happens is 854374.)

This is fixed in e93fc5a on master and ddfe667 on the 1.6 branch.

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Hiro Asari added a comment - - edited This is a rather peculiar problem. Note https://github.com/jruby/jruby/blob/81cd13e2fe6ee2f87b769851aeefedb626091e96/src/org/jruby/util/Numeric.java#L476 Under some circumstances, this test evaluates to false unexpectedly (because x*x overflows the 'long' range and ends up in just the right range) and we return a wrong value. (The smallest integer for which this happens is 854374.) This is fixed in e93fc5a on master and ddfe667 on the 1.6 branch.

People

  • Assignee:
    Hiro Asari
    Reporter:
    Yasunori Miyamoto
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Dates

  • Created:
    Updated:
    Resolved: