[OM] Add om.map attribute (#5869)

This implement  a `om.map` attribute as constant of map types.

include/circt/Dialect/OM/OMAttributes.td

@@ -81,4 +81,26 @@ def OMListAttr : AttrDef<OMDialect, "List", [TypedAttrInterface]> {
   }];
 }
 
+def MapAttr : AttrDef<OMDialect, "Map", [TypedAttrInterface]> {
+  let summary = "An attribute that represents a string map";
+
+  let mnemonic = "map";
+
+  let parameters = (ins
+    "mlir::Type": $valueType,
+    "mlir::DictionaryAttr":$elements
+  );
+
+  // TODO: Use custom assembly format to infer a type from elements.
+  let assemblyFormat = [{
+    `<` $valueType `,` $elements `>`
+  }];
+
+  let genVerifyDecl = 1;
+
+  let extraClassDeclaration = [{
+    mlir::Type getType();
+  }];
+}
+
 #endif // CIRCT_DIALECT_OM_OMATTRIBUTES_TD

lib/Dialect/OM/OMAttributes.cpp

@@ -14,6 +14,7 @@
 #include "circt/Dialect/OM/OMDialect.h"
 #include "circt/Dialect/OM/OMTypes.h"
 #include "mlir/IR/Builders.h"
+#include "mlir/IR/BuiltinAttributes.h"
 #include "mlir/IR/DialectImplementation.h"
 #include "llvm/ADT/TypeSwitch.h"
 
@@ -35,6 +36,11 @@ Type circt::om::ListAttr::getType() {
   return ListType::get(getContext(), getElementType());
 }
 
+Type circt::om::MapAttr::getType() {
+  return MapType::get(getContext(), StringType::get(getContext()),
+                      getValueType());
+}
+
 circt::om::SymbolRefAttr circt::om::SymbolRefAttr::get(mlir::Operation *op) {
   return om::SymbolRefAttr::get(op->getContext(),
                                 mlir::FlatSymbolRefAttr::get(op));
@@ -67,6 +73,24 @@ circt::om::ListAttr::verify(function_ref<InFlightDiagnostic()> emitError,
   }));
 }
 
+LogicalResult
+circt::om::MapAttr::verify(function_ref<InFlightDiagnostic()> emitError,
+                           mlir::Type valueType,
+                           mlir::DictionaryAttr elements) {
+  for (auto attr : elements) {
+    auto typedAttr = llvm::dyn_cast<mlir::TypedAttr>(attr.getValue());
+    if (!typedAttr)
+      return emitError()
+             << "a value of a map attribute must be a typed attr but got "
+             << attr.getValue();
+    if (typedAttr.getType() != valueType)
+      return emitError() << "a value of a map attribute must have a type "
+                         << valueType << " but field " << attr.getName()
+                         << " has " << typedAttr.getType();
+  }
+  return success();
+}
+
 void circt::om::OMDialect::registerAttributes() {
   addAttributes<
 #define GET_ATTRDEF_LIST

test/Dialect/OM/errors.mlir

@@ -109,3 +109,10 @@ om.class @Tuple(%tuple: tuple<i1, !om.string>) {
   // expected-error @+1 {{tuple index out-of-bounds, must be less than 2 but got 2}}
   %val = om.tuple_get %tuple[2]  : tuple<i1, !om.string>
 }
+
+// -----
+
+om.class @MapConstant() {
+  // expected-error @+1 {{a value of a map attribute must have a type 'i64' but field "b" has '!om.list<i32>'}}
+  %0 = om.constant #om.map<i64, {a = 42, b = #om.list<i32, []>}> : !om.map<!om.string, i64>
+}

test/Dialect/OM/round-trip.mlir

@@ -183,3 +183,11 @@ om.class @Tuple(%int: i1, %str: !om.string) {
   // CHECK-NEXT: om.class.field @val, %[[tuple_get]] : !om.string
   om.class.field @val, %val : !om.string
 }
+
+// CHECK-LABEL: @MapConstant
+om.class @MapConstant() {
+  // CHECK: %[[const1:.+]] = om.constant #om.map<i64, {a = 42 : i64, b = 32 : i64}> : !om.map<!om.string, i64>
+  %0 = om.constant #om.map<i64, {a = 42, b = 32}> : !om.map<!om.string, i64>
+  // CHECK: om.class.field @map_i64, %[[const1]] : !om.map<!om.string, i64>
+  om.class.field @map_i64, %0 : !om.map<!om.string, i64>
+}