don't bother touching volatile stores, they will just return clobber on

everything interesting anyway.

llvm-svn: 60640

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
index 92431c3fe31..8b40da656ee 100644
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -90,6 +90,11 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
     // If we find a store or a free, get it's memory dependence.
     if (!isa<StoreInst>(Inst) && !isa<FreeInst>(Inst))
       continue;
+    
+    // Don't molest volatile stores or do queries that will return "clobber".
+    if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
+      if (SI->isVolatile())
+        continue;
 
     MemDepResult InstDep = MD.getDependency(Inst);