JDK-6667588 : Don't generate duplicated CMP for float/double values
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: hs12
  • Priority: P4
  • Status: Closed
  • Resolution: Fixed
  • OS: solaris_10
  • CPU: sparc
  • Submitted: 2008-02-26
  • Updated: 2013-11-01
  • Resolved: 2011-04-20
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JDK 6 Other
6u14Fixed hs12Fixed
Description
C2 has optimization which replaces diamond graphs with CMove
(method PhaseIdealLoop::conditional_move()).
Each CMove instruction has own Cmp instruction to produce condition flags.
But float/double Cmp is expensive and it would be better to use a diamond graph
if we have more then one move.
Comments
SUGGESTED FIX Don't generate float CMove instruction if there are more then one Move depending on the condition.
03-03-2008
EVALUATION See description.
03-03-2008