Don't allow the automatically updated MI flags to be set directly.

The bundle-related MI flags need to be kept in sync with the neighboring
instructions. Don't allow the bulk flag-setting setFlags() function to
change them.

Also don't copy MI flags when cloning an instruction. The clone's bundle
flags will be set when it is explicitly inserted into a bundle.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170459 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineInstr.h

@@ -150,7 +150,9 @@ public:
   }
 
   void setFlags(unsigned flags) {
-    Flags = flags;
+    // Filter out the automatically maintained flags.
+    unsigned Mask = BundledPred | BundledSucc;
+    Flags = (Flags & Mask) | (flags & ~Mask);
   }
 
   /// clearFlag - Clear a MI flag.