Add a const lookup routine to get a BlockAddress constant if there is

one, but not create one. This is useful in the verifier when we want to
query the constant if it exists but not create one. To be used in an
upcoming commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199568 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 19 insertions, 2 deletions

diff --git a/include/llvm/IR/Constants.h b/include/llvm/IR/Constants.h
index 1acf5b6cc8..448d82931a 100644
--- a/include/llvm/IR/Constants.h
+++ b/include/llvm/IR/Constants.h
@@ -757,6 +757,12 @@ public:
   /// block must be embedded into a function.
   static BlockAddress *get(BasicBlock *BB);
 
+  /// \brief Lookup an existing \c BlockAddress constant for the given
+  /// BasicBlock.
+  ///
+  /// \returns 0 if \c !BB->hasAddressTaken(), otherwise the \c BlockAddress.
+  static BlockAddress *lookup(const BasicBlock *BB);
+
   /// Transparently provide more efficient getOperand methods.
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 
diff --git a/lib/IR/Constants.cpp b/lib/IR/Constants.cpp
index 1f6f5ac427..ecd2cfd9fd 100644
--- a/lib/IR/Constants.cpp
+++ b/lib/IR/Constants.cpp
@@ -1375,6 +1375,17 @@ BlockAddress::BlockAddress(Function *F, BasicBlock *BB)
   BB->AdjustBlockAddressRefCount(1);
 }
 
+BlockAddress *BlockAddress::lookup(const BasicBlock *BB) {
+  if (!BB->hasAddressTaken())
+    return 0;
+
+  const Function *F = BB->getParent();
+  assert(F != 0 && "Block must have a parent");
+  BlockAddress *BA =
+      F->getContext().pImpl->BlockAddresses.lookup(std::make_pair(F, BB));
+  assert(BA && "Refcount and block address map disagree!");
+  return BA;
+}
 
 // destroyConstant - Remove the constant from the constant table.
 //
diff --git a/lib/IR/LLVMContextImpl.h b/lib/IR/LLVMContextImpl.h
index 39e5d778ed..0433827246 100644
--- a/lib/IR/LLVMContextImpl.h
+++ b/lib/IR/LLVMContextImpl.h
@@ -281,8 +281,8 @@ public:
   
   StringMap<ConstantDataSequential*> CDSConstants;
 
-  
-  DenseMap<std::pair<Function*, BasicBlock*> , BlockAddress*> BlockAddresses;
+  DenseMap<std::pair<const Function *, const BasicBlock *>, BlockAddress *>
+    BlockAddresses;
   ConstantUniqueMap<ExprMapKeyType, const ExprMapKeyType&, Type, ConstantExpr>
     ExprConstants;