[TableGen] Simplify emitULEB128 in DecoderEmitter.cpp. NFC (#130214)

Instead of returning the number of bytes emitted, just take the iterator
by reference so the increments in emitULEB128 will update the copy in
the caller.

Also pass the iterator by reference to emitNumToSkip so we don't need a
separate I += 3 in the caller.

Author: topperc

llvm/utils/TableGen/DecoderEmitter.cpp

@@ -808,19 +808,15 @@ void DecoderEmitter::emitTable(formatted_raw_ostream &OS, DecoderTable &Table,
   Indent += 2;
 
   // Emit ULEB128 encoded value to OS, returning the number of bytes emitted.
-  auto emitULEB128 = [](DecoderTable::const_iterator I,
+  auto emitULEB128 = [](DecoderTable::const_iterator &I,
                         formatted_raw_ostream &OS) {
-    unsigned Len = 0;
-    while (*I >= 128) {
+    while (*I >= 128)
       OS << (unsigned)*I++ << ", ";
-      Len++;
-    }
     OS << (unsigned)*I++ << ", ";
-    return Len + 1;
   };
 
   // Emit 24-bit numtoskip value to OS, returning the NumToSkip value.
-  auto emitNumToSkip = [](DecoderTable::const_iterator I,
+  auto emitNumToSkip = [](DecoderTable::const_iterator &I,
                           formatted_raw_ostream &OS) {
     uint8_t Byte = *I++;
     uint32_t NumToSkip = Byte;
@@ -857,7 +853,7 @@ void DecoderEmitter::emitTable(formatted_raw_ostream &OS, DecoderTable &Table,
       unsigned Start = decodeULEB128(Table.data() + Pos + 1, nullptr,
                                      Table.data() + Table.size(), &ErrMsg);
       assert(ErrMsg == nullptr && "ULEB128 value too large!");
-      I += emitULEB128(I, OS);
+      emitULEB128(I, OS);
 
       unsigned Len = *I++;
       OS << Len << ",  // Inst{";
@@ -870,39 +866,36 @@ void DecoderEmitter::emitTable(formatted_raw_ostream &OS, DecoderTable &Table,
       ++I;
       OS << Indent << "MCD::OPC_FilterValue, ";
       // The filter value is ULEB128 encoded.
-      I += emitULEB128(I, OS);
+      emitULEB128(I, OS);
 
       // 24-bit numtoskip value.
       uint32_t NumToSkip = emitNumToSkip(I, OS);
-      I += 3;
       OS << "// Skip to: " << ((I - Table.begin()) + NumToSkip) << "\n";
       break;
     }
     case MCD::OPC_CheckField: {
       ++I;
       OS << Indent << "MCD::OPC_CheckField, ";
       // ULEB128 encoded start value.
-      I += emitULEB128(I, OS);
+      emitULEB128(I, OS);
       // 8-bit length.
       unsigned Len = *I++;
       OS << Len << ", ";
       // ULEB128 encoded field value.
-      I += emitULEB128(I, OS);
+      emitULEB128(I, OS);
 
       // 24-bit numtoskip value.
       uint32_t NumToSkip = emitNumToSkip(I, OS);
-      I += 3;
       OS << "// Skip to: " << ((I - Table.begin()) + NumToSkip) << "\n";
       break;
     }
     case MCD::OPC_CheckPredicate: {
       ++I;
       OS << Indent << "MCD::OPC_CheckPredicate, ";
-      I += emitULEB128(I, OS);
+      emitULEB128(I, OS);
 
       // 24-bit numtoskip value.
       uint32_t NumToSkip = emitNumToSkip(I, OS);
-      I += 3;
       OS << "// Skip to: " << ((I - Table.begin()) + NumToSkip) << "\n";
       break;
     }
@@ -917,10 +910,10 @@ void DecoderEmitter::emitTable(formatted_raw_ostream &OS, DecoderTable &Table,
       assert(ErrMsg == nullptr && "ULEB128 value too large!");
 
       OS << Indent << "MCD::OPC_" << (IsTry ? "Try" : "") << "Decode, ";
-      I += emitULEB128(I, OS);
+      emitULEB128(I, OS);
 
       // Decoder index.
-      I += emitULEB128(I, OS);
+      emitULEB128(I, OS);
 
       auto EncI = OpcodeToEncodingID.find(Opc);
       assert(EncI != OpcodeToEncodingID.end() && "no encoding entry");
@@ -935,7 +928,6 @@ void DecoderEmitter::emitTable(formatted_raw_ostream &OS, DecoderTable &Table,
 
       // 24-bit numtoskip value.
       uint32_t NumToSkip = emitNumToSkip(I, OS);
-      I += 3;
 
       OS << "// Opcode: " << NumberedEncodings[EncodingID]
          << ", skip to: " << ((I - Table.begin()) + NumToSkip) << "\n";