Make blockaddress(@func, null) be valid, and make 'deleting a basic

block with a blockaddress still referring to it' replace the invalid 
blockaddress with a new blockaddress(@func, null) instead of a 
inttoptr(1).

This changes the bitcode encoding format, and still needs codegen 
support (this should produce a non-zero value, referring to the entry
block of the function would also be quite reasonable).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85678 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 10 insertions, 8 deletions

diff --git a/lib/VMCore/AsmWriter.cpp b/lib/VMCore/AsmWriter.cpp
index 9a803a1..df1d19b 100644
--- a/lib/VMCore/AsmWriter.cpp
+++ b/lib/VMCore/AsmWriter.cpp
@@ -1065,7 +1065,10 @@ static void WriteConstantInt(raw_ostream &Out, const Constant *CV,
     Out << "blockaddress(";
     WriteAsOperandInternal(Out, BA->getFunction(), &TypePrinter, Machine);
     Out << ", ";
-    WriteAsOperandInternal(Out, BA->getBasicBlock(), &TypePrinter, Machine);
+    if (BA->getBasicBlock())
+      WriteAsOperandInternal(Out, BA->getBasicBlock(), &TypePrinter, Machine);
+    else
+      Out << "null";
     Out << ")";
     return;
   }
diff --git a/lib/VMCore/BasicBlock.cpp b/lib/VMCore/BasicBlock.cpp
index 23d0557..c609ef8 100644
--- a/lib/VMCore/BasicBlock.cpp
+++ b/lib/VMCore/BasicBlock.cpp
@@ -63,15 +63,13 @@ BasicBlock::~BasicBlock() {
   // hanging off the block, or an undefined use of the block (source code
   // expecting the address of a label to keep the block alive even though there
   // is no indirect branch).  Handle these cases by zapping the BlockAddress
-  // nodes.  There are no other possible uses at this point.
+  // nodes, replacing them with BlockAddress(F, NULL).  There are no other
+  // possible uses at this point.
   if (hasAddressTaken()) {
     assert(!use_empty() && "There should be at least one blockaddress!");
-    Constant *Replacement =
-      ConstantInt::get(llvm::Type::getInt32Ty(getContext()), 1);
     while (!use_empty()) {
       BlockAddress *BA = cast<BlockAddress>(use_back());
-      BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement,
-                                                       BA->getType()));
+      BA->replaceAllUsesWith(BlockAddress::get(BA->getFunction(), 0));
       BA->destroyConstant();
     }
   }
diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp
index 2d3d71b..e0adf9d 100644
--- a/lib/VMCore/Constants.cpp
+++ b/lib/VMCore/Constants.cpp
@@ -1045,7 +1045,7 @@ BlockAddress::BlockAddress(Function *F, BasicBlock *BB)
            &Op<0>(), 2) {
   Op<0>() = F;
   Op<1>() = BB;
-  BB->AdjustBlockAddressRefCount(1);
+  if (BB) BB->AdjustBlockAddressRefCount(1);
 }
 
 
@@ -1054,7 +1054,8 @@ BlockAddress::BlockAddress(Function *F, BasicBlock *BB)
 void BlockAddress::destroyConstant() {
   getFunction()->getType()->getContext().pImpl
     ->BlockAddresses.erase(std::make_pair(getFunction(), getBasicBlock()));
-  getBasicBlock()->AdjustBlockAddressRefCount(-1);
+  if (BasicBlock *BB = getBasicBlock())
+    BB->AdjustBlockAddressRefCount(-1);
   destroyConstantImpl();
 }