[OM] Support list concatenation in the Evaluator. (#7511)

List concatenation is implemented by first ensuring all the sub-lists
are evaluated, and then appending the elements of each sub-list into
the final ListValue that represents the concatenation of the lists.

include/circt/Dialect/OM/Evaluator/Evaluator.h

@@ -481,6 +481,9 @@ struct Evaluator {
   FailureOr<EvaluatorValuePtr> evaluateListCreate(ListCreateOp op,
                                                   ActualParameters actualParams,
                                                   Location loc);
+  FailureOr<EvaluatorValuePtr> evaluateListConcat(ListConcatOp op,
+                                                  ActualParameters actualParams,
+                                                  Location loc);
   FailureOr<EvaluatorValuePtr>
   evaluateTupleCreate(TupleCreateOp op, ActualParameters actualParams,
                       Location loc);

lib/Dialect/OM/Evaluator/Evaluator.cpp

@@ -167,10 +167,10 @@ FailureOr<evaluator::EvaluatorValuePtr> circt::om::Evaluator::getOrCreateValue(
                           evaluator::PathValue::getEmptyPath(loc));
                   return success(result);
                 })
-                .Case<ListCreateOp, TupleCreateOp, MapCreateOp, ObjectFieldOp>(
-                    [&](auto op) {
-                      return getPartiallyEvaluatedValue(op.getType(), loc);
-                    })
+                .Case<ListCreateOp, ListConcatOp, TupleCreateOp, MapCreateOp,
+                      ObjectFieldOp>([&](auto op) {
+                  return getPartiallyEvaluatedValue(op.getType(), loc);
+                })
                 .Case<ObjectOp>([&](auto op) {
                   return getPartiallyEvaluatedValue(op.getType(), op.getLoc());
                 })
@@ -360,6 +360,9 @@ circt::om::Evaluator::evaluateValue(Value value, ActualParameters actualParams,
             .Case([&](ListCreateOp op) {
               return evaluateListCreate(op, actualParams, loc);
             })
+            .Case([&](ListConcatOp op) {
+              return evaluateListConcat(op, actualParams, loc);
+            })
             .Case([&](TupleCreateOp op) {
               return evaluateTupleCreate(op, actualParams, loc);
             })
@@ -583,6 +586,45 @@ circt::om::Evaluator::evaluateListCreate(ListCreateOp op,
   return list;
 }
 
+/// Evaluator dispatch function for List concatenation.
+FailureOr<evaluator::EvaluatorValuePtr>
+circt::om::Evaluator::evaluateListConcat(ListConcatOp op,
+                                         ActualParameters actualParams,
+                                         Location loc) {
+  // Evaluate the List concat op itself, in case it hasn't been evaluated yet.
+  SmallVector<evaluator::EvaluatorValuePtr> values;
+  auto list = getOrCreateValue(op, actualParams, loc);
+
+  // Extract the ListValue, either directly or through an object reference.
+  auto extractList = [](evaluator::EvaluatorValue *value) {
+    return std::move(
+        llvm::TypeSwitch<evaluator::EvaluatorValue *, evaluator::ListValue *>(
+            value)
+            .Case([](evaluator::ListValue *val) { return val; })
+            .Case([](evaluator::ReferenceValue *val) {
+              return cast<evaluator::ListValue>(val->getStrippedValue()->get());
+            }));
+  };
+
+  for (auto operand : op.getOperands()) {
+    auto result = evaluateValue(operand, actualParams, loc);
+    if (failed(result))
+      return result;
+    if (!result.value()->isFullyEvaluated())
+      return list;
+
+    // Append each EvaluatorValue from the sublist.
+    evaluator::ListValue *subList = extractList(result.value().get());
+    for (auto subValue : subList->getElements())
+      values.push_back(subValue);
+  }
+
+  // Return the concatenated list.
+  llvm::cast<evaluator::ListValue>(list.value().get())
+      ->setElements(std::move(values));
+  return list;
+}
+
 /// Evaluator dispatch function for Tuple creation.
 FailureOr<evaluator::EvaluatorValuePtr>
 circt::om::Evaluator::evaluateTupleCreate(TupleCreateOp op,

unittests/Dialect/OM/Evaluator/EvaluatorTests.cpp

@@ -919,4 +919,115 @@ TEST(EvaluatorTests, IntegerBinaryArithmeticWidthMismatch) {
                    .getValue());
 }
 
+TEST(EvaluatorTests, ListConcat) {
+  StringRef mod = "om.class @ListConcat() {"
+                  "  %0 = om.constant #om.integer<0 : i8> : !om.integer"
+                  "  %1 = om.constant #om.integer<1 : i8> : !om.integer"
+                  "  %2 = om.constant #om.integer<2 : i8> : !om.integer"
+                  "  %l0 = om.list_create %0, %1 : !om.integer"
+                  "  %l1 = om.list_create %2 : !om.integer"
+                  "  %concat = om.list_concat %l0, %l1 : !om.list<!om.integer>"
+                  "  om.class.field @result, %concat : !om.list<!om.integer>"
+                  "}";
+
+  DialectRegistry registry;
+  registry.insert<OMDialect>();
+
+  MLIRContext context(registry);
+  context.getOrLoadDialect<OMDialect>();
+
+  OwningOpRef<ModuleOp> owning =
+      parseSourceString<ModuleOp>(mod, ParserConfig(&context));
+
+  Evaluator evaluator(owning.release());
+
+  auto result =
+      evaluator.instantiate(StringAttr::get(&context, "ListConcat"), {});
+
+  ASSERT_TRUE(succeeded(result));
+
+  auto fieldValue = llvm::cast<evaluator::ObjectValue>(result.value().get())
+                        ->getField("result")
+                        .value();
+
+  auto finalList =
+      llvm::cast<evaluator::ListValue>(fieldValue.get())->getElements();
+
+  ASSERT_EQ(3, finalList.size());
+
+  ASSERT_EQ(0, llvm::cast<evaluator::AttributeValue>(finalList[0].get())
+                   ->getAs<circt::om::IntegerAttr>()
+                   .getValue()
+                   .getValue());
+
+  ASSERT_EQ(1, llvm::cast<evaluator::AttributeValue>(finalList[1].get())
+                   ->getAs<circt::om::IntegerAttr>()
+                   .getValue()
+                   .getValue());
+
+  ASSERT_EQ(2, llvm::cast<evaluator::AttributeValue>(finalList[2].get())
+                   ->getAs<circt::om::IntegerAttr>()
+                   .getValue()
+                   .getValue());
+}
+
+TEST(EvaluatorTests, ListConcatField) {
+  StringRef mod =
+      "om.class @ListField() {"
+      "  %0 = om.constant #om.integer<2 : i8> : !om.integer"
+      "  %1 = om.list_create %0 : !om.integer"
+      "  om.class.field @value, %1 : !om.list<!om.integer>"
+      "}"
+      "om.class @ListConcatField() {"
+      "  %listField = om.object @ListField() : () -> !om.class.type<@ListField>"
+      "  %0 = om.constant #om.integer<0 : i8> : !om.integer"
+      "  %1 = om.constant #om.integer<1 : i8> : !om.integer"
+      "  %l0 = om.list_create %0, %1 : !om.integer"
+      "  %l1 = om.object.field %listField, [@value] : "
+      "(!om.class.type<@ListField>) -> !om.list<!om.integer>"
+      "  %concat = om.list_concat %l0, %l1 : !om.list<!om.integer>"
+      "  om.class.field @result, %concat : !om.list<!om.integer>"
+      "}";
+
+  DialectRegistry registry;
+  registry.insert<OMDialect>();
+
+  MLIRContext context(registry);
+  context.getOrLoadDialect<OMDialect>();
+
+  OwningOpRef<ModuleOp> owning =
+      parseSourceString<ModuleOp>(mod, ParserConfig(&context));
+
+  Evaluator evaluator(owning.release());
+
+  auto result =
+      evaluator.instantiate(StringAttr::get(&context, "ListConcatField"), {});
+
+  ASSERT_TRUE(succeeded(result));
+
+  auto fieldValue = llvm::cast<evaluator::ObjectValue>(result.value().get())
+                        ->getField("result")
+                        .value();
+
+  auto finalList =
+      llvm::cast<evaluator::ListValue>(fieldValue.get())->getElements();
+
+  ASSERT_EQ(3, finalList.size());
+
+  ASSERT_EQ(0, llvm::cast<evaluator::AttributeValue>(finalList[0].get())
+                   ->getAs<circt::om::IntegerAttr>()
+                   .getValue()
+                   .getValue());
+
+  ASSERT_EQ(1, llvm::cast<evaluator::AttributeValue>(finalList[1].get())
+                   ->getAs<circt::om::IntegerAttr>()
+                   .getValue()
+                   .getValue());
+
+  ASSERT_EQ(2, llvm::cast<evaluator::AttributeValue>(finalList[2].get())
+                   ->getAs<circt::om::IntegerAttr>()
+                   .getValue()
+                   .getValue());
+}
+
 } // namespace