2 files changed, 10 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 19746651d99..56983dc6036 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -3268,6 +3268,15 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
   return visitCallSite(II);
 }
 
+// Fence instruction simplification
+Instruction *InstCombiner::visitFenceInst(FenceInst &FI) {
+  // Remove identical consecutive fences.
+  if (auto *NFI = dyn_cast<FenceInst>(FI.getNextNode()))
+    if (FI.isIdenticalTo(NFI))
+      return eraseInstFromFunction(FI);
+  return nullptr;
+}
+
 // InvokeInst simplification
 //
 Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 9c684f11087..9f16a6f6e1e 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -289,6 +289,7 @@ public:
   Instruction *visitLoadInst(LoadInst &LI);
   Instruction *visitStoreInst(StoreInst &SI);
   Instruction *visitBranchInst(BranchInst &BI);
+  Instruction *visitFenceInst(FenceInst &FI);
   Instruction *visitSwitchInst(SwitchInst &SI);
   Instruction *visitReturnInst(ReturnInst &RI);
   Instruction *visitInsertValueInst(InsertValueInst &IV);