Make MDNode use CallbackVH. Also change MDNode to store Value* instead of

Constant* in preperation of a future change to support holding non-Constants
in an MDNode.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71407 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Bitcode/Reader/BitcodeReader.cpp

@@ -17,6 +17,7 @@
 #include "llvm/DerivedTypes.h"
 #include "llvm/InlineAsm.h"
 #include "llvm/Instructions.h"
+#include "llvm/MDNode.h"
 #include "llvm/Module.h"
 #include "llvm/AutoUpgrade.h"
 #include "llvm/ADT/SmallString.h"
@@ -287,12 +288,10 @@ void BitcodeReaderValueList::ResolveConstantForwardRefs() {
                                    UserCS->getType()->isPacked());
       } else if (isa<ConstantVector>(UserC)) {
         NewC = ConstantVector::get(&NewOps[0], NewOps.size());
-      } else if (isa<ConstantExpr>(UserC)) {
+      } else {
+        assert(isa<ConstantExpr>(UserC) && "Must be a ConstantExpr.");
         NewC = cast<ConstantExpr>(UserC)->getWithOperands(&NewOps[0],
                                                           NewOps.size());
-      } else {
-        assert(isa<MDNode>(UserC) && "Must be a metadata node.");
-        NewC = MDNode::get(&NewOps[0], NewOps.size());
       }
       
       UserC->replaceAllUsesWith(NewC);
@@ -300,6 +299,8 @@ void BitcodeReaderValueList::ResolveConstantForwardRefs() {
       NewOps.clear();
     }
     
+    // Update all ValueHandles, they should be the only users at this point.
+    Placeholder->replaceAllUsesWith(RealVal);
     delete Placeholder;
   }
 }
@@ -1017,10 +1018,13 @@ bool BitcodeReader::ParseConstants() {
         return Error("Invalid CST_MDNODE record");
       
       unsigned Size = Record.size();
-      SmallVector<Constant*, 8> Elts;
+      SmallVector<Value*, 8> Elts;
       for (unsigned i = 0; i != Size; i += 2) {
         const Type *Ty = getTypeByID(Record[i], false);
-        Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], Ty));
+        if (Ty != Type::VoidTy)
+          Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], Ty));
+        else
+          Elts.push_back(NULL);
       }
       V = MDNode::get(&Elts[0], Elts.size());
       break;

lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -19,6 +19,7 @@
 #include "llvm/DerivedTypes.h"
 #include "llvm/InlineAsm.h"
 #include "llvm/Instructions.h"
+#include "llvm/MDNode.h"
 #include "llvm/Module.h"
 #include "llvm/TypeSymbolTable.h"
 #include "llvm/ValueSymbolTable.h"
@@ -706,9 +707,14 @@ static void WriteConstants(unsigned FirstVal, unsigned LastVal,
       }
     } else if (const MDNode *N = dyn_cast<MDNode>(C)) {
       Code = bitc::CST_CODE_MDNODE;
-      for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
-        Record.push_back(VE.getTypeID(N->getOperand(i)->getType()));
-        Record.push_back(VE.getValueID(N->getOperand(i)));
+      for (unsigned i = 0, e = N->getNumElements(); i != e; ++i) {
+        if (N->getElement(i)) {
+          Record.push_back(VE.getTypeID(N->getElement(i)->getType()));
+          Record.push_back(VE.getValueID(N->getElement(i)));
+        } else {
+          Record.push_back(VE.getTypeID(Type::VoidTy));
+          Record.push_back(0);
+        }
       }
     } else {
       assert(0 && "Unknown constant!");

lib/Bitcode/Writer/ValueEnumerator.cpp

@@ -14,6 +14,7 @@
 #include "ValueEnumerator.h"
 #include "llvm/Constants.h"
 #include "llvm/DerivedTypes.h"
+#include "llvm/MDNode.h"
 #include "llvm/Module.h"
 #include "llvm/TypeSymbolTable.h"
 #include "llvm/ValueSymbolTable.h"
@@ -200,6 +201,18 @@ void ValueEnumerator::EnumerateValue(const Value *V) {
       
       // Finally, add the value.  Doing this could make the ValueID reference be
       // dangling, don't reuse it.
+      Values.push_back(std::make_pair(V, 1U));
+      ValueMap[V] = Values.size();
+      return;
+    } else if (const MDNode *N = dyn_cast<MDNode>(C)) {
+      for (MDNode::const_elem_iterator I = N->elem_begin(), E = N->elem_end();
+           I != E; ++I) {
+        if (*I)
+          EnumerateValue(*I);
+        else
+          EnumerateType(Type::VoidTy);
+      }
+
       Values.push_back(std::make_pair(V, 1U));
       ValueMap[V] = Values.size();
       return;
@@ -244,6 +257,11 @@ void ValueEnumerator::EnumerateOperandType(const Value *V) {
     // them.
     for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
       EnumerateOperandType(C->getOperand(i));
+
+    if (const MDNode *N = dyn_cast<MDNode>(V)) {
+      for (unsigned i = 0, e = N->getNumElements(); i != e; ++i)
+        EnumerateOperandType(N->getElement(i));
+    }
   }
 }