Address the Rabbit's comments

Author: denialhaag

mlir/include/mlir/Dialect/QC/Translation/TranslateQASM3ToQC.h

@@ -19,15 +19,20 @@
 namespace mlir::qc {
 
 /**
- * @brief Import a QASM3 program directly into the QC dialect.
+ * @brief Translate an OpenQASM3 program to the QC dialect.
  *
- * @details Bypasses qc::QuantumComputation: the parser produces an AST walked
- * by an InstVisitor that emits QC dialect ops via QCProgramBuilder.
- * Returns nullptr on failure (diagnostics written to llvm::errs()).
+ * @param context MLIRContext to create the module in.
+ * @param filename Path to the input OpenQASM3 file.
  */
 [[nodiscard]] OwningOpRef<ModuleOp>
 translateQASM3ToQC(MLIRContext* context, const std::string& filename);
 
+/**
+ * @brief Translate an OpenQASM3 program to the QC dialect.
+ *
+ * @param context MLIRContext to create the module in.
+ * @param input Stream containing the OpenQASM3 program.
+ */
 [[nodiscard]] OwningOpRef<ModuleOp> translateQASM3ToQC(MLIRContext* context,
                                                        std::istream& input);
 

mlir/lib/Dialect/QC/Translation/TranslateQASM3ToQC.cpp

@@ -326,7 +326,8 @@ class MLIRQasmImporter final : public qasm3::InstVisitor {
       break;
     }
     default:
-      break;
+      throw qasm3::CompilerError("Unsupported declaration type.",
+                                 stmt->debugInfo);
     }
 
     // Handle initializer (measure only)
@@ -431,11 +432,12 @@ class MLIRQasmImporter final : public qasm3::InstVisitor {
     }
     for (size_t i = 0; i < qubits.size(); ++i) {
       // Use the MeasureOp directly to capture the i1 result for if/else
-      auto measureOp = MeasureOp::create(
-          builder, qubits[i], builder.getStringAttr(bits[i].registerName),
-          builder.getI64IntegerAttr(bits[i].registerSize),
-          builder.getI64IntegerAttr(bits[i].registerIndex));
-      Value result = measureOp.getResult();
+      auto result =
+          MeasureOp::create(builder, qubits[i],
+                            builder.getStringAttr(bits[i].registerName),
+                            builder.getI64IntegerAttr(bits[i].registerSize),
+                            builder.getI64IntegerAttr(bits[i].registerIndex))
+              .getResult();
 
       // Track the result for use in if/else conditions
       const auto& regName = bits[i].registerName;
@@ -470,7 +472,7 @@ class MLIRQasmImporter final : public qasm3::InstVisitor {
       return;
     }
 
-    Value condition = translateCondition(stmt->condition, stmt->debugInfo);
+    auto condition = translateCondition(stmt->condition, stmt->debugInfo);
     const bool hasElse = !stmt->elseStatements.empty();
 
     auto ifOp =
@@ -581,7 +583,8 @@ class MLIRQasmImporter final : public qasm3::InstVisitor {
     size_t ctrlIdx = 0;
     for (const auto& [n, positive] : ctrlSpec) {
       for (size_t i = 0; i < n; ++i, ++ctrlIdx) {
-        if (expandedOperands[ctrlIdx].size() != 1) {
+        if (ctrlIdx >= expandedOperands.size() ||
+            expandedOperands[ctrlIdx].size() != 1) {
           throw qasm3::CompilerError("Control operand must be a single qubit.",
                                      stmt->debugInfo);
         }
@@ -660,7 +663,7 @@ class MLIRQasmImporter final : public qasm3::InstVisitor {
 
       // Check that no qubit appears twice across targets and controls.
       llvm::SmallDenseSet<Value> seen;
-      for (auto q : concat<const Value>(iterQubits, posControls, negControls)) {
+      for (auto q : concat<Value>(iterQubits, posControls, negControls)) {
         if (!seen.insert(q).second) {
           throw qasm3::CompilerError("Duplicate qubit in gate '" + id +
                                          "' operands.",
@@ -732,7 +735,7 @@ class MLIRQasmImporter final : public qasm3::InstVisitor {
     if (const auto binaryExpr =
             std::dynamic_pointer_cast<qasm3::BinaryExpression>(condition)) {
       throw qasm3::CompilerError(
-          "Register comparisons cannot be translated to QC at the moment",
+          "Register comparisons cannot be translated to QC at the moment.",
           debugInfo);
     }
 
@@ -743,11 +746,17 @@ class MLIRQasmImporter final : public qasm3::InstVisitor {
              unaryExpr->op == qasm3::UnaryExpression::BitwiseNot);
       const auto idExpr = std::dynamic_pointer_cast<qasm3::IndexedIdentifier>(
           unaryExpr->operand);
-      Value bitVal = lookupBitValue(idExpr, debugInfo);
+      if (!idExpr) {
+        throw qasm3::CompilerError("Unary expression has unsupported operand.",
+                                   debugInfo);
+      }
+      auto bitVal = lookupBitValue(idExpr, debugInfo);
       // Negate: XOR with true
-      Value trueVal = arith::ConstantOp::create(
-          builder, builder.getIntegerAttr(builder.getI1Type(), 1));
-      return arith::XOrIOp::create(builder, bitVal, trueVal);
+      auto trueVal =
+          arith::ConstantOp::create(
+              builder, builder.getIntegerAttr(builder.getI1Type(), 1))
+              .getResult();
+      return arith::XOrIOp::create(builder, bitVal, trueVal).getResult();
     }
 
     // Case 3: Single bit (c[0] — truthy)

mlir/tools/mqt-cc/mqt-cc.cpp

@@ -87,7 +87,7 @@ static llvm::cl::opt<bool> enableHadamardLifting(
  */
 static OwningOpRef<ModuleOp> loadQASMFile(StringRef filename,
                                           MLIRContext* context) {
-  return mlir::qc::translateQASM3ToQC(context, filename.str());
+  return qc::translateQASM3ToQC(context, filename.str());
 }
 
 /**
@@ -134,15 +134,14 @@ int main(int argc, char** argv) {
 
   // Set up MLIR context with all required dialects
   DialectRegistry registry;
-  registry.insert<mlir::qc::QCDialect>();
+  registry.insert<qc::QCDialect>();
   registry.insert<qco::QCODialect>();
   registry.insert<arith::ArithDialect>();
   registry.insert<cf::ControlFlowDialect>();
   registry.insert<func::FuncDialect>();
   registry.insert<memref::MemRefDialect>();
   registry.insert<scf::SCFDialect>();
   registry.insert<LLVM::LLVMDialect>();
-  registry.insert<mlir::memref::MemRefDialect>();
   registry.insert<qtensor::QTensorDialect>();
 
   MLIRContext context(registry);