JDK-7120448 : Fix FP values for compiled frames in frame::describe
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: hs23
  • Priority: P5
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2011-12-12
  • Updated: 2012-04-10
  • Resolved: 2012-04-10
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JDK 7 JDK 8 Other
7u4Fixed 8Fixed hs23Fixed
Related Reports
Relates :  
For a compiled frame, the frame top depends on the initial (unextended) sp and the compiled frame size.

frame::describe has not been completely fixed. Its uses of [extended] sp() and of [non computed] fp() can result in a bad top address being printed and being used as a boundary while dumping compiled frames

EVALUATION http://hg.openjdk.java.net/lambda/lambda/hotspot/rev/eaa9557116a2

EVALUATION http://hg.openjdk.java.net/hsx/hotspot-comp/hotspot/rev/eaa9557116a2

EVALUATION frame::describe() was calling the platform dependent frame::fp() to get the frame pointer. Unfortunately, the semantic of frame::fp() is not clearly defined. On compiled x86 frames, the value could be arbitrary. That could cause frame::describe to dump misleading information and useless memory slots. Defined a new frame::real_fp() with a more precise semantic for portable shared code. This is the value expected by the platform ABI when it defines a frame pointer register. It may differ from the effective value of the FP register when that register is used in the JVM for other purposes (like compiled frames on some platforms). On other platforms, it is defined so that the stack area used by this frame goes from real_fp() to sp(). By default, the new definition is equivalent to the old frame::fp() definition. x86 is the only OpenJDK supported platform which required a different definition.