[RegisterBankInfo] Take advantage of the extra argument of SmallVector::resize.

When initializing an instance of OperandsMapper, instead of using
SmallVector::resize followed by std::fill, use the function that
directly does that in SmallVector.

llvm-svn: 282130

llvm/lib/CodeGen/GlobalISel/RegisterBankInfo.cpp

@@ -513,9 +513,7 @@ RegisterBankInfo::OperandsMapper::OperandsMapper(
     MachineRegisterInfo &MRI)
     : MRI(MRI), MI(MI), InstrMapping(InstrMapping) {
   unsigned NumOpds = MI.getNumOperands();
-  OpToNewVRegIdx.resize(NumOpds);
-  std::fill(OpToNewVRegIdx.begin(), OpToNewVRegIdx.end(),
-            OperandsMapper::DontKnowIdx);
+  OpToNewVRegIdx.resize(NumOpds, OperandsMapper::DontKnowIdx);
   assert(InstrMapping.verify(MI) && "Invalid mapping for MI");
 }