Map MDNode correctly.

A non function local MDNode can have an operand which is cloned by MapValue(). 

llvm-svn: 109117

1 files changed, 27 insertions, 6 deletions

diff --git a/llvm/lib/Transforms/Utils/ValueMapper.cpp b/llvm/lib/Transforms/Utils/ValueMapper.cpp
index 3f6a90c94eb..1cd5cca9b6e 100644
--- a/llvm/lib/Transforms/Utils/ValueMapper.cpp
+++ b/llvm/lib/Transforms/Utils/ValueMapper.cpp
@@ -14,6 +14,7 @@
 
 #include "ValueMapper.h"
 #include "llvm/Type.h"
+#include "llvm/GlobalAlias.h"
 #include "llvm/Constants.h"
 #include "llvm/Function.h"
 #include "llvm/Metadata.h"
@@ -29,15 +30,35 @@ Value *llvm::MapValue(const Value *V, ValueToValueMapTy &VM) {
 
   // Global values and non-function-local metadata do not need to be seeded into
   // the VM if they are using the identity mapping.
-  if (isa<GlobalValue>(V) || isa<InlineAsm>(V) || isa<MDString>(V) ||
-      (isa<MDNode>(V) && !cast<MDNode>(V)->isFunctionLocal()))
+  if (isa<GlobalValue>(V) || isa<InlineAsm>(V) || isa<MDString>(V))
     return VMSlot = const_cast<Value*>(V);
 
   if (const MDNode *MD = dyn_cast<MDNode>(V)) {
-    SmallVector<Value*, 4> Elts;
-    for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i)
-      Elts.push_back(MD->getOperand(i) ? MapValue(MD->getOperand(i), VM) : 0);
-    return VM[V] = MDNode::get(V->getContext(), Elts.data(), Elts.size());
+    Value *Dummy = new GlobalAlias(V->getType(), GlobalValue::ExternalLinkage);
+    VMSlot = Dummy;
+    for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i) {
+      Value *OP = MD->getOperand(i);
+      if (!OP) continue;
+      Value *MV = MapValue(OP, VM);
+      if (MV != OP) {
+        // This MDNode contain a reference to mapped value. Make a new
+        // MDNode and return it.
+        SmallVector<Value*, 4> Elts;
+        Elts.reserve(MD->getNumOperands());
+        for (unsigned j = 0; j != i; ++j)
+          Elts.push_back(MD->getOperand(j));
+        Elts.push_back(MV);
+        for (++i; i != e; ++i)
+          Elts.push_back(MD->getOperand(i) ? 
+                         MapValue(MD->getOperand(i), VM) : 0);
+        MDNode *NewMD = MDNode::get(V->getContext(), Elts.data(), Elts.size());
+        Dummy->uncheckedReplaceAllUsesWith(NewMD);
+        delete Dummy;
+        return VM[V] = NewMD;
+      }
+    }
+    delete Dummy;
+    return VM[V] = const_cast<Value*>(V);
   }
 
   Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V));