Tristate mayLoad, mayStore, and hasSideEffects.

Keep track of the set/unset state of these bits along with their
true/false values, but treat '?' as '0' for now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162461 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/CodeGenInstruction.h b/utils/TableGen/CodeGenInstruction.h
index 7484237..7637a5b 100644
--- a/utils/TableGen/CodeGenInstruction.h
+++ b/utils/TableGen/CodeGenInstruction.h
@@ -226,7 +226,10 @@
     bool isBarrier;
     bool isCall;
     bool canFoldAsLoad;
-    bool mayLoad, mayStore;
+    bool mayLoad;
+    bool mayLoad_Unset;
+    bool mayStore;
+    bool mayStore_Unset;
     bool isPredicable;
     bool isConvertibleToThreeAddress;
     bool isCommutable;
@@ -238,6 +241,7 @@
     bool hasCtrlDep;
     bool isNotDuplicable;
     bool hasSideEffects;
+    bool hasSideEffects_Unset;
     bool neverHasSideEffects;
     bool isAsCheapAsAMove;
     bool hasExtraSrcRegAllocReq;