Fix PR2967 by not deleting volatile load/stores that occur before unreachable.
I don't really see this as being needed, but there is little harm from doing
it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58385 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 7f41336..596c564 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1932,7 +1932,18 @@
while (Unreachable != BB->begin()) {
BasicBlock::iterator BBI = Unreachable;
--BBI;
+ // Do not delete instructions that can have side effects, like calls
+ // (which may never return) and volatile loads and stores.
if (isa<CallInst>(BBI)) break;
+
+ if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
+ if (SI->isVolatile())
+ break;
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(BBI))
+ if (LI->isVolatile())
+ break;
+
// Delete this instruction
BB->getInstList().erase(BBI);
Changed = true;