From: Chris Lattner <sabre@nondot.org>
Date: Sun, 7 Dec 2008 00:25:15 +0000 (+0000)
Subject: don't bother touching volatile stores, they will just return clobber on
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f760be1c7fd793e103f788687e4efdcad2464b58;p=oota-llvm.git

don't bother touching volatile stores, they will just return clobber on
everything interesting anyway.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60640 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp
index 92431c3fe31..8b40da656ee 100644
--- a/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/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);