[Function] Properly remove use when clearing personality

Summary:
We need to actually remove the use of the personality function,
otherwise we can run into trouble if we want to e.g. delete
the personality function because ther's no way to get rid of
its uses. Do this by resetting to ConstantPointerNull value
that the operands are set to when first allocated.

Reviewers: vsk, dexonsmith

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D15752

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256345 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/IR/Function.cpp b/lib/IR/Function.cpp
index f5974a63f45643b5c71f0c972580cbdf3a1186aa..cfb40b19c733123bc703da49442a235854fdce7f 100644 (file)
--- a/lib/IR/Function.cpp
+++ b/lib/IR/Function.cpp
@@ -942,8 +942,7 @@ Constant *Function::getPersonalityFn() const {
 }
 
 void Function::setPersonalityFn(Constant *Fn) {
-  if (Fn)
-    setHungoffOperand<0>(Fn);
+  setHungoffOperand<0>(Fn);
   setValueSubclassDataBit(3, Fn != nullptr);
 }
 
@@ -953,8 +952,7 @@ Constant *Function::getPrefixData() const {
 }
 
 void Function::setPrefixData(Constant *PrefixData) {
-  if (PrefixData)
-    setHungoffOperand<1>(PrefixData);
+  setHungoffOperand<1>(PrefixData);
   setValueSubclassDataBit(1, PrefixData != nullptr);
 }
 
@@ -964,8 +962,7 @@ Constant *Function::getPrologueData() const {
 }
 
 void Function::setPrologueData(Constant *PrologueData) {
-  if (PrologueData)
-    setHungoffOperand<2>(PrologueData);
+  setHungoffOperand<2>(PrologueData);
   setValueSubclassDataBit(2, PrologueData != nullptr);
 }
 
@@ -986,9 +983,13 @@ void Function::allocHungoffUselist() {
 
 template <int Idx>
 void Function::setHungoffOperand(Constant *C) {
-  assert(C && "Cannot set hungoff operand to nullptr");
-  allocHungoffUselist();
-  Op<Idx>().set(C);
+  if (C) {
+    allocHungoffUselist();
+    Op<Idx>().set(C);
+  } else if (getNumOperands()) {
+    Op<Idx>().set(
+        ConstantPointerNull::get(Type::getInt1PtrTy(getContext(), 0)));
+  }
 }
 
 void Function::setValueSubclassDataBit(unsigned Bit, bool On) {

diff --git a/unittests/IR/UserTest.cpp b/unittests/IR/UserTest.cpp
index 56b054b6835967662fa477b6f344672d088e97bb..8d488389448a1eb6dc059e136927ca315d64c777 100644 (file)
--- a/unittests/IR/UserTest.cpp
+++ b/unittests/IR/UserTest.cpp
@@ -93,4 +93,28 @@ TEST(UserTest, ValueOpIteration) {
   EXPECT_EQ(P.value_op_end(), (I - 2) + 8);
 }
 
+TEST(UserTest, PersonalityUser) {
+  Module M("", getGlobalContext());
+  FunctionType *RetVoidTy =
+      FunctionType::get(Type::getVoidTy(getGlobalContext()), false);
+  Function *PersonalityF = Function::Create(
+      RetVoidTy, GlobalValue::ExternalLinkage, "PersonalityFn", &M);
+  Function *TestF =
+      Function::Create(RetVoidTy, GlobalValue::ExternalLinkage, "TestFn", &M);
+
+  // Set up the personality function
+  TestF->setPersonalityFn(PersonalityF);
+  auto PersonalityUsers = PersonalityF->user_begin();
+
+  // One user and that user is the Test function
+  EXPECT_EQ(*PersonalityUsers, TestF);
+  EXPECT_EQ(++PersonalityUsers, PersonalityF->user_end());
+
+  // Reset the personality function
+  TestF->setPersonalityFn(nullptr);
+
+  // No users should remain
+  EXPECT_TRUE(TestF->user_empty());
+}
+
 } // end anonymous namespace