Convert assert(0) to llvm_unreachable

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149967 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index b8ead89..150868d 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -703,8 +703,7 @@
   if (ShadowRedzoneSize == 4)
     return (PoisonByte << 24) + (PoisonByte << 16) +
         (PoisonByte << 8) + (PoisonByte);
-  assert(0 && "ShadowRedzoneSize is either 1, 2 or 4");
-  return 0;
+  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
 }
 
 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,