Replace a few uses of SelectionDAG::getTargetNode with SelectionDAG::SelectNodeTo in the instruction selector. This updates existing nodes in place instead of creating new ones.
Replace a few uses of SelectionDAG::getTargetNode with
SelectionDAG::SelectNodeTo in the instruction selector. This
updates existing nodes in place instead of creating new ones.

Go back to selecting ISD::DBG_LABEL nodes into
TargetInstrInfo::DBG_LABEL nodes instead of leaving them
unselected, now that SelectNodeTo allows us to update them
in place.


git-svn-id: a4a6f32337ebd29ad4763b423022f00f68d1c7b7@53057 91177308-0d34-0410-b5e6-96231b3b80d8

lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx,lodyagin/bare_cxx