add default ctor.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75114 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/MachineInstrBuilder.h b/include/llvm/CodeGen/MachineInstrBuilder.h
index c6a6679c1b69b0d0b4b3e178e3d71deab46667ea..73611fe7db1e5982ec23aaeb3f11084363ae7bad 100644 (file)
--- a/include/llvm/CodeGen/MachineInstrBuilder.h
+++ b/include/llvm/CodeGen/MachineInstrBuilder.h
@@ -39,6 +39,7 @@ namespace RegState {
 class MachineInstrBuilder {
   MachineInstr *MI;
 public:
+  MachineInstrBuilder() : MI(0) {}
   explicit MachineInstrBuilder(MachineInstr *mi) : MI(mi) {}
 
   /// Allow automatic conversion to the machine instruction we are working on.