[SystemZ] Make operator bool explicit. NFC.

llvm-svn: 219069

llvm/lib/Target/SystemZ/SystemZElimCompare.cpp

@@ -47,7 +47,7 @@ struct Reference {
     return *this;
   }
 
-  operator bool() const { return Def || Use; }
+  LLVM_EXPLICIT operator bool() const { return Def || Use; }
 
   // True if the register is defined or used in some form, either directly or
   // via a sub- or super-register.

llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp

@@ -633,7 +633,7 @@ struct LogicOp {
   LogicOp(unsigned regSize, unsigned immLSB, unsigned immSize)
     : RegSize(regSize), ImmLSB(immLSB), ImmSize(immSize) {}
 
-  operator bool() const { return RegSize; }
+  LLVM_EXPLICIT operator bool() const { return RegSize; }
 
   unsigned RegSize, ImmLSB, ImmSize;
 };