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

[Craig Topper via llvm-commits]

https://github.com/topperc created https://github.com/llvm/llvm-project/pull/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 I += 3 after it.

>From bc280f3c059ca92f0753624c5d1859b6b6ef9ffa Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Thu, 6 Mar 2025 16:49:00 -0800
Subject: [PATCH] [TableGen] Simplify emitULEB128 in DecoderEmitter.cpp. NFC

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 I += 3 after it.
---
 llvm/utils/TableGen/DecoderEmitter.cpp | 28 +++++++++-----------------
 1 file changed, 10 insertions(+), 18 deletions(-)

diff --git a/llvm/utils/TableGen/DecoderEmitter.cpp b/llvm/utils/TableGen/DecoderEmitter.cpp
index 8947e887eaa3e..0b07c7004cdda 100644
--- a/llvm/utils/TableGen/DecoderEmitter.cpp
+++ b/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{";
@@ -870,11 +866,10 @@ 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;
     }
@@ -882,27 +877,25 @@ void DecoderEmitter::emitTable(formatted_raw_ostream &OS, DecoderTable &Table,
       ++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";