3 files changed, 15 insertions, 13 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index dfdf677a797..5ae56215944 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -4324,9 +4324,7 @@ Instruction *InstCombiner::visitCallBase(CallBase &Call) {
         // variety of reasons (e.g. it may be written in assembly).
         !CalleeF->isDeclaration()) {
       Instruction *OldCall = &Call;
-      new StoreInst(ConstantInt::getTrue(Callee->getContext()),
-                UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
-                                  OldCall);
+      CreateNonTerminatorUnreachable(OldCall);
       // If OldCall does not return void then replaceAllUsesWith undef.
       // This allows ValueHandlers and custom metadata to adjust itself.
       if (!OldCall->getType()->isVoidTy())
@@ -4356,13 +4354,8 @@ Instruction *InstCombiner::visitCallBase(CallBase &Call) {
       return nullptr;
     }
 
-    // This instruction is not reachable, just remove it.  We insert a store to
-    // undef so that we know that this code is not reachable, despite the fact
-    // that we can't modify the CFG here.
-    new StoreInst(ConstantInt::getTrue(Callee->getContext()),
-                  UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
-                  &Call);
-
+    // This instruction is not reachable, just remove it.
+    CreateNonTerminatorUnreachable(&Call);
     return eraseInstFromFunction(Call);
   }
 
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index a42cf95b45a..0488f7bd07a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -656,6 +656,16 @@ public:
     return InsertValueInst::Create(Struct, Result, 0);
   }
 
+  /// Create and insert the idiom we use to indicate a block is unreachable
+  /// without having to rewrite the CFG from within InstCombine.
+  void CreateNonTerminatorUnreachable(Instruction *InsertAt) {
+    auto &Ctx = InsertAt->getContext();
+    new StoreInst(ConstantInt::getTrue(Ctx),
+                  UndefValue::get(Type::getInt1PtrTy(Ctx)),
+                  InsertAt);
+  }
+
+
   /// Combiner aware instruction erasure.
   ///
   /// When dealing with an instruction that has side effects or produces a void
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 963542c50d8..d7a1feb06b8 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2475,9 +2475,8 @@ Instruction *InstCombiner::visitFree(CallInst &FI) {
 
   // free undef -> unreachable.
   if (isa<UndefValue>(Op)) {
-    // Insert a new store to null because we cannot modify the CFG here.
-    Builder.CreateStore(ConstantInt::getTrue(FI.getContext()),
-                        UndefValue::get(Type::getInt1PtrTy(FI.getContext())));
+    // Leave a marker since we can't modify the CFG here.
+    CreateNonTerminatorUnreachable(&FI);
     return eraseInstFromFunction(FI);
   }