From c05cb8d561c1a6a4509f1e707ed281729e878c27 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Sun, 13 Jun 2010 14:35:54 +0000
Subject: [PATCH] SimplifyCFG: don't turn volatile stores to null/undef into
 unreachable. Fixes PR7369.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105914 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/SimplifyCFGPass.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/lib/Transforms/Scalar/SimplifyCFGPass.cpp
index 97441008c46..49d93a2fcc2 100644
--- a/lib/Transforms/Scalar/SimplifyCFGPass.cpp
+++ b/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -137,6 +137,9 @@ static bool MarkAliveBlocks(BasicBlock *BB,
       // they should be changed to unreachable by passes that can't modify the
       // CFG.
       if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
+        // Don't touch volatile stores.
+        if (SI->isVolatile()) continue;
+
         Value *Ptr = SI->getOperand(1);
         
         if (isa<UndefValue>(Ptr) ||
-- 
2.34.1