[MachineVerifier] Avoid reference to nullptr

Instantiation of the MachineVerifierPass through
PassInfo::getNormalCtor would yield a segfault since the default
constructor of the MachineVerifierPass takes a reference to nullptr.

Patch by Simone Pellegrini.

Differential Revision: https://reviews.llvm.org/D31387

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298987 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/MachineVerifier.cpp b/lib/CodeGen/MachineVerifier.cpp
index 15694cb481f6858b7da148a6fe2a2a6c8bc27ccb..5c263b3021f59bd7158876ee11c55a1964aff427 100644 (file)
--- a/lib/CodeGen/MachineVerifier.cpp
+++ b/lib/CodeGen/MachineVerifier.cpp
@@ -260,8 +260,8 @@ namespace {
     static char ID; // Pass ID, replacement for typeid
     const std::string Banner;
 
-    MachineVerifierPass(const std::string &banner = nullptr)
-      : MachineFunctionPass(ID), Banner(banner) {
+    MachineVerifierPass(const std::string banner = std::string())
+      : MachineFunctionPass(ID), Banner(std::move(banner)) {
         initializeMachineVerifierPassPass(*PassRegistry::getPassRegistry());
       }