[RISCV] Add missing namespace (NFC)

[achieveartificialintelligence]

clang/utils/TableGen/RISCVVEmitter.cpp

300

We have used
using namespace llvm;

[fakepaper56]

The main reason I want to add the prefix "llvm::" is all None in the files are "llvm::None" form. But also it is more feasible when we want to add a variable name 'None' in the file.

[khchen]

The main reason I want to add the prefix "llvm::" is all None in the files are "llvm::None" form.

It makes sense to me.

[achieveartificialintelligence]

OK, LGTM. Thanks! @fakepaper56 @khchen

[fakepaper56]

The patch content is in D119727.

clang/utils/TableGen/RISCVVEmitter.cpp

case 32:
     Log2ScaleResult = Log2LMUL + 1;
     break;
   case 64:
     Log2ScaleResult = Log2LMUL;
     break;
   }
   // Illegal vscale result would be less than 1
   if (Log2ScaleResult < 0)
-    return None;
+    return llvm::None;
   return 1 << Log2ScaleResult;
 }
 
 void LMULType::MulLog2LMUL(int log2LMUL) { Log2LMUL += log2LMUL; }
 
 LMULType &LMULType::operator*=(uint32_t RHS) {
   assert(isPowerOf2_32(RHS));
   this->Log2LMUL = this->Log2LMUL + Log2_32(RHS);