[llvm] [TableGen][InstrInfo] Cull mapping that have not been enabled/not needed (PR #126137)

[Rahul Joshi via llvm-commits]

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@@ -376,73 +387,66 @@ void InstrInfoEmitter::emitOperandTypeMappings(
     return NumberedInstructions[I]->TheDef->getName();
   };
   // TODO: Factor out duplicate operand lists to compress the tables.
-  if (!NumberedInstructions.empty()) {
-    std::vector<int> OperandOffsets;
-    std::vector<const Record *> OperandRecords;
-    int CurrentOffset = 0;
-    for (const CodeGenInstruction *Inst : NumberedInstructions) {
-      OperandOffsets.push_back(CurrentOffset);
-      for (const auto &Op : Inst->Operands) {
-        const DagInit *MIOI = Op.MIOperandInfo;
-        if (!ExpandMIOperandInfo || !MIOI || MIOI->getNumArgs() == 0) {
-          // Single, anonymous, operand.
-          OperandRecords.push_back(Op.Rec);
+  std::vector<size_t> OperandOffsets;
+  std::vector<const Record *> OperandRecords;
+  size_t CurrentOffset = 0;
+  for (const CodeGenInstruction *Inst : NumberedInstructions) {
+    OperandOffsets.push_back(CurrentOffset);
+    for (const auto &Op : Inst->Operands) {
+      const DagInit *MIOI = Op.MIOperandInfo;
+      if (!ExpandMIOperandInfo || !MIOI || MIOI->getNumArgs() == 0) {
+        // Single, anonymous, operand.
+        OperandRecords.push_back(Op.Rec);
+        ++CurrentOffset;
+      } else {
+        for (const Init *Arg : MIOI->getArgs()) {
+          OperandRecords.push_back(cast<DefInit>(Arg)->getDef());
           ++CurrentOffset;
-        } else {
-          for (const Init *Arg : MIOI->getArgs()) {
-            OperandRecords.push_back(cast<DefInit>(Arg)->getDef());
-            ++CurrentOffset;
-          }
         }
       }
     }
+  }
 
-    // Emit the table of offsets (indexes) into the operand type table.
-    // Size the unsigned integer offset to save space.
-    assert(OperandRecords.size() <= UINT32_MAX &&
-           "Too many operands for offset table");
-    OS << "  static const " << getMinimalTypeForRange(OperandRecords.size());
-    OS << " Offsets[] = {\n";
-    for (int I = 0, E = OperandOffsets.size(); I != E; ++I) {
-      OS << "    /* " << getInstrName(I) << " */\n";
-      OS << "    " << OperandOffsets[I] << ",\n";
-    }
-    OS << "  };\n";
+  // Emit the table of offsets (indexes) into the operand type table.
+  // Size the unsigned integer offset to save space.
+  assert(OperandRecords.size() <= UINT32_MAX &&
+         "Too many operands for offset table");
+  OS << "  static constexpr " << getMinimalTypeForRange(OperandRecords.size());
+  OS << " Offsets[] = {\n";
+  for (const auto &[Idx, Offset] : enumerate(OperandOffsets))
----------------
jurahul wrote:

slight format change for compactness: `<offset> // instruction_name`

https://github.com/llvm/llvm-project/pull/126137