diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 26df55531a8..f9abafa34c0 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -9066,7 +9066,7 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) { // the pointer we're loading and is producing the pointer we're storing, // then *this* store is dead (X = load P; store X -> P). if (LoadInst *LI = dyn_cast(BBI)) { - if (LI == Val && LI->getOperand(0) == Ptr) { + if (LI == Val && LI->getOperand(0) == Ptr && !SI.isVolatile()) { EraseInstFromFunction(SI); ++NumCombined; return 0; diff --git a/test/Transforms/InstCombine/volatile_store.ll b/test/Transforms/InstCombine/volatile_store.ll new file mode 100644 index 00000000000..09651ba302d --- /dev/null +++ b/test/Transforms/InstCombine/volatile_store.ll @@ -0,0 +1,14 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {volatile store} +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {volatile load} + +@x = weak global i32 0 ; [#uses=2] + +define void @self_assign_1() { +entry: + %tmp = volatile load i32* @x ; [#uses=1] + volatile store i32 %tmp, i32* @x + br label %return + +return: ; preds = %entry + ret void +}