1 files changed, 28 insertions, 0 deletions
diff --git a/llvm/unittests/Transforms/Utils/BasicBlockUtils.cpp b/llvm/unittests/Transforms/Utils/BasicBlockUtils.cpp
index 2d0a9302011..590e7f6ada6 100644
--- a/llvm/unittests/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/unittests/Transforms/Utils/BasicBlockUtils.cpp
@@ -50,3 +50,31 @@ TEST(BasicBlockUtils, SplitBlockPredecessors) {
   SplitBlockPredecessors(&F->getEntryBlock(), {}, "split.entry", &DT);
   EXPECT_TRUE(DT.verify());
 }
+
+TEST(BasicBlockUtils, MergeBlockIntoPredecessor) {
+  LLVMContext C;
+  std::unique_ptr<Module> M = parseIR(C,
+                                      R"(
+
+      define i32 @f(i8* %str) {
+      entry:
+        %dead = extractvalue [1 x i8*] [ i8* blockaddress(@f, %L0) ], 0
+        br label %L0
+      L0:
+        ret i32 0
+      }
+      )");
+
+  // First remove the dead instruction to empty the usage of the constant
+  // containing blockaddress(@f, %L0)
+  Function *F = M->getFunction("f");
+  auto BBI = F->begin();
+  Instruction *DI = &*((*BBI).begin());
+  EXPECT_TRUE(DI->use_empty());
+  DI->eraseFromParent();
+
+  // Get L0 and make sure that it can be merged into entry block.
+  ++BBI;
+  BasicBlock *BB = &(*BBI);
+  EXPECT_TRUE(MergeBlockIntoPredecessor(BB));
+}