Revert the earlier change that removed the M_REMATERIALIZABLE machine
instruction flag, and use the flag along with a virtual member function
hook for targets to override if there are instructions that are only
trivially rematerializable with specific operands (i.e. constant pool
loads).

llvm-svn: 37728
diff --git a/llvm/utils/TableGen/CodeGenTarget.cpp b/llvm/utils/TableGen/CodeGenTarget.cpp
index b02c423..c54ecd0 100644
--- a/llvm/utils/TableGen/CodeGenTarget.cpp
+++ b/llvm/utils/TableGen/CodeGenTarget.cpp
@@ -365,6 +365,7 @@
   isConvertibleToThreeAddress = R->getValueAsBit("isConvertibleToThreeAddress");
   isCommutable = R->getValueAsBit("isCommutable");
   isTerminator = R->getValueAsBit("isTerminator");
+  isReMaterializable = R->getValueAsBit("isReMaterializable");
   hasDelaySlot = R->getValueAsBit("hasDelaySlot");
   usesCustomDAGSchedInserter = R->getValueAsBit("usesCustomDAGSchedInserter");
   hasCtrlDep   = R->getValueAsBit("hasCtrlDep");