[PATCH] IR: add failure ordering to the cmpxchg instruction

[Chandler Carruth]

  This looks good to me, with the provision that we should probably bump the bitcode version.

  While this change is *backwards* compatible to old bitcodes, it is not forwards compatible. Put another way, old bitcode readers will stop working, and so we should pus the version number forward so they get a version error rather than a structural error.

  I'm fine with you committing this briefly until you hear back from someone about the bitcode version -- until we make a release, nothing like that is set in stone, so we can fix the bitcode versions #s.


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Comment at: include/llvm/CodeGen/SelectionDAGNodes.h:1096
@@ +1095,3 @@
+
+
+  void InitAtomic(AtomicOrdering SuccessOrdering,
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Spurious blank line?


http://llvm-reviews.chandlerc.com/D3023