JDK-7092905 : C2: Keep track of the number of dead nodes
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2011-09-20
  • Updated: 2015-03-02
  • Resolved: 2012-12-12
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JDK 7 JDK 8 Other
7u40Fixed 8 b68Fixed hs24Fixed
Related Reports
Relates :  
JDK-8011858 - Use Compile::live_nodes() instead of Compile::unique() in appropriate places
Relates :  
JDK-7081842 - assert(Compile::current()->unique() < (uint)MaxNodeLimit) failed: Node limit exceeded
Description
When nodes limit is reached during compilation of a method C2 bail out compilation and disable further compilations of such method which is too drastic.
Comments
Keep an (almost) accurate running count of the reachable (live) flow graph nodes. This would give a more realistic node count for various phases of C2 to decide on whether to proceed with optimizations or not. Prior to this change, C2 bails out of compilation based on the number of nodes created which typically larger than number of reachable (live) nodes.
28-11-2012