tree fd9bbe0f1c581bcc7c05bbfb2643ffe0b1fb014e
parent dd4cbcc924c8ba2a578914a4a366996693bdcd74
author Roland Levillain <rpl@google.com> 1447409251 +0000
committer Roland Levillain <rpl@google.com> 1447589801 +0000

x86/x86-64 read barrier support for concurrent GC in Optimizing.

This first implementation uses slow paths to instrument heap
reference loads and GC root loads for the concurrent copying
collector, respectively calling the artReadBarrierSlow and
artReadBarrierForRootSlow (new) runtime entry points.

Notes:
- This implementation does not instrument HInvokeVirtual
  nor HInvokeInterface instructions (for class reference
  loads), as the corresponding read barriers are not stricly
  required with the current concurrent copying collector.
- Intrinsics which may eventually call (on slow path) are
  disabled when read barriers are enabled, as the current
  slow path infrastructure does not support this case.
- When read barriers are enabled, the code generated for a
  HArraySet instruction always go into the array set slow
  path for object arrays (delegating the operation to the
  runtime), as we are lacking a mechanism to keep a
  temporary register live accross a runtime call (needed for
  the instrumentation of type checking code, which requires
  two successive read barriers).

Bug: 12687968
Change-Id: I14cd6107233c326389120336f93955b28ffbb329