From: Chris Lattner <sabre@nondot.org>
Date: Tue, 30 Nov 2010 00:12:39 +0000 (+0000)
Subject: my previous patch would cause us to start deleting some volatile
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=184d1ba73866b688cef5f78a214e3fb964b6d833;p=oota-llvm.git

my previous patch would cause us to start deleting some volatile
stores, fix and add a testcase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120363 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp
index e1d89cb9109..dd66416e7fe 100644
--- a/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -222,7 +222,7 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
     if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
       if (LoadInst *DepLoad = dyn_cast<LoadInst>(InstDep.getInst())) {
         if (SI->getPointerOperand() == DepLoad->getPointerOperand() &&
-            SI->getOperand(0) == DepLoad) {
+            SI->getOperand(0) == DepLoad && !SI->isVolatile()) {
           // DeleteDeadInstruction can delete the current instruction.  Save BBI
           // in case we need it.
           WeakVH NextInst(BBI);
diff --git a/test/Transforms/DeadStoreElimination/simple.ll b/test/Transforms/DeadStoreElimination/simple.ll
index 6aba1d2125e..05e0d351dee 100644
--- a/test/Transforms/DeadStoreElimination/simple.ll
+++ b/test/Transforms/DeadStoreElimination/simple.ll
@@ -34,3 +34,23 @@ define i32 @test3(i32* %g_addr) nounwind {
   %tmp3 = load i32* @g, align 4
   ret i32 %tmp3
 }
+
+
+define void @test4(i32* %Q) {
+        %a = load i32* %Q
+        volatile store i32 %a, i32* %Q
+        ret void
+; CHECK: @test4
+; CHECK-NEXT: load i32
+; CHECK-NEXT: volatile store
+; CHECK-NEXT: ret void
+}
+
+define void @test5(i32* %Q) {
+        %a = volatile load i32* %Q
+        store i32 %a, i32* %Q
+        ret void
+; CHECK: @test5
+; CHECK-NEXT: volatile load
+; CHECK-NEXT: ret void
+}