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| author | Chris Lattner <sabre@nondot.org> | 2007-09-07 05:33:03 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2007-09-07 05:33:03 +0000 |
| commit | a54c7eb15708bf5654a99c66cb7d633f52831555 (patch) | |
| tree | 3e1293daa2e5389cf2326bf0f0d47cc983d40cd8 | |
| parent | 718cb665ca6ce2bc4d8e8479f46a45db91b49f86 (diff) | |
Don't zap back to back volatile load/stores
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41759 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 2 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/volatile_store.ll | 14 |
2 files changed, 15 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 26df55531a..f9abafa34c 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<LoadInst>(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 0000000000..09651ba302 --- /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 ; <i32*> [#uses=2] + +define void @self_assign_1() { +entry: + %tmp = volatile load i32* @x ; <i32> [#uses=1] + volatile store i32 %tmp, i32* @x + br label %return + +return: ; preds = %entry + ret void +} |