IR: Add fp operations to atomicrmw

Add just fadd/fsub for now.

llvm-svn: 351778

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -1034,6 +1034,8 @@ static AtomicRMWInst::BinOp getDecodedRMWOperation(unsigned Val) {
   case bitc::RMW_MIN: return AtomicRMWInst::Min;
   case bitc::RMW_UMAX: return AtomicRMWInst::UMax;
   case bitc::RMW_UMIN: return AtomicRMWInst::UMin;
+  case bitc::RMW_FADD: return AtomicRMWInst::FAdd;
+  case bitc::RMW_FSUB: return AtomicRMWInst::FSub;
   }
 }