Update LLVM for rebase to r212749.

Includes a cherry-pick of:
r212948 - fixes a small issue with atomic calls

Change-Id: Ib97bd980b59f18142a69506400911a6009d9df18
diff --git a/lib/Bitcode/Writer/ValueEnumerator.cpp b/lib/Bitcode/Writer/ValueEnumerator.cpp
index 8531e76..15f8034 100644
--- a/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -73,37 +73,34 @@
   SmallVector<std::pair<unsigned, MDNode*>, 8> MDs;
 
   // Enumerate types used by function bodies and argument lists.
-  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
+  for (const Function &F : *M) {
+    for (const Argument &A : F.args())
+      EnumerateType(A.getType());
 
-    for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
-         I != E; ++I)
-      EnumerateType(I->getType());
-
-    for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
-      for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
-        for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
-             OI != E; ++OI) {
-          if (MDNode *MD = dyn_cast<MDNode>(*OI))
+    for (const BasicBlock &BB : F)
+      for (const Instruction &I : BB) {
+        for (const Use &Op : I.operands()) {
+          if (MDNode *MD = dyn_cast<MDNode>(&Op))
             if (MD->isFunctionLocal() && MD->getFunction())
               // These will get enumerated during function-incorporation.
               continue;
-          EnumerateOperandType(*OI);
+          EnumerateOperandType(Op);
         }
-        EnumerateType(I->getType());
-        if (const CallInst *CI = dyn_cast<CallInst>(I))
+        EnumerateType(I.getType());
+        if (const CallInst *CI = dyn_cast<CallInst>(&I))
           EnumerateAttributes(CI->getAttributes());
-        else if (const InvokeInst *II = dyn_cast<InvokeInst>(I))
+        else if (const InvokeInst *II = dyn_cast<InvokeInst>(&I))
           EnumerateAttributes(II->getAttributes());
 
         // Enumerate metadata attached with this instruction.
         MDs.clear();
-        I->getAllMetadataOtherThanDebugLoc(MDs);
+        I.getAllMetadataOtherThanDebugLoc(MDs);
         for (unsigned i = 0, e = MDs.size(); i != e; ++i)
           EnumerateMetadata(MDs[i].second);
 
-        if (!I->getDebugLoc().isUnknown()) {
+        if (!I.getDebugLoc().isUnknown()) {
           MDNode *Scope, *IA;
-          I->getDebugLoc().getScopeAndInlinedAt(Scope, IA, I->getContext());
+          I.getDebugLoc().getScopeAndInlinedAt(Scope, IA, I.getContext());
           if (Scope) EnumerateMetadata(Scope);
           if (IA) EnumerateMetadata(IA);
         }
@@ -120,6 +117,12 @@
   return I->second;
 }
 
+unsigned ValueEnumerator::getComdatID(const Comdat *C) const {
+  unsigned ComdatID = Comdats.idFor(C);
+  assert(ComdatID && "Comdat not found!");
+  return ComdatID;
+}
+
 void ValueEnumerator::setInstructionID(const Instruction *I) {
   InstructionMap[I] = InstructionCount++;
 }
@@ -310,6 +313,10 @@
     return;
   }
 
+  if (auto *GO = dyn_cast<GlobalObject>(V))
+    if (const Comdat *C = GO->getComdat())
+      Comdats.insert(C);
+
   // Enumerate the type of this value.
   EnumerateType(V->getType());