fix an issue where the verifier would reject a function whose entry

block had its address taken even if the blockaddress was dead.

llvm-svn: 85706

llvm/include/llvm/BasicBlock.h

@@ -240,6 +240,10 @@ public:
   /// hasAddressTaken - returns true if there are any uses of this basic block
   /// other than direct branches, switches, etc. to it.
   bool hasAddressTaken() const { return SubclassData != 0; }
+                     
+  /// removeDeadBlockAddress - If there is a blockaddress node for this basic
+  /// block, try to remove it and any dead constant users of it.
+  void removeDeadBlockAddress();
 private:
   /// AdjustBlockAddressRefCount - BasicBlock stores the number of BlockAddress
   /// objects using it.  This is almost always 0, sometimes one, possibly but

llvm/lib/VMCore/Globals.cpp

@@ -75,6 +75,14 @@ void GlobalValue::removeDeadConstantUsers() const {
   }
 }
 
+/// removeDeadBlockAddress - If there is a blockaddress node for this basic
+/// block, try to remove it and any dead constant users of it.
+void BasicBlock::removeDeadBlockAddress() {
+  if (!hasAddressTaken()) return;
+  removeDeadUsersOfConstant(BlockAddress::get(this));
+}
+
+
 /// Override destroyConstant to make sure it doesn't get called on
 /// GlobalValue's because they shouldn't be treated like other constants.
 void GlobalValue::destroyConstant() {

llvm/lib/VMCore/Verifier.cpp

@@ -658,8 +658,13 @@ void Verifier::visitFunction(Function &F) {
     BasicBlock *Entry = &F.getEntryBlock();
     Assert1(pred_begin(Entry) == pred_end(Entry),
             "Entry block to function must not have predecessors!", Entry);
-    Assert1(!Entry->hasAddressTaken(),
-            "blockaddress may not be used with the entry block!", Entry);
+    
+    // The address of the entry block cannot be taken, unless it is dead.
+    if (Entry->hasAddressTaken()) {
+      Entry->removeDeadBlockAddress();
+      Assert1(!Entry->hasAddressTaken(),
+              "blockaddress may not be used with the entry block!", Entry);
+    }
   }
   
   // If this function is actually an intrinsic, verify that it is only used in