core: Add attributes to func outputs (#3661)

Mlir
[supports](https://mlir.llvm.org/docs/Dialects/Func/#funcfunc-funcfuncop)
attributes for output types. We need for cross compatibility with other
mlir projects.

tests/filecheck/dialects/func/func_ops.mlir

@@ -71,4 +71,14 @@ builtin.module {
   // CHECK:       func.func public @arg_attrs(%{{.*}} : tensor<8x8xf64> {"llvm.noalias"}, %{{.*}} : tensor<8x8xf64> {"llvm.noalias"}, %{{.*}} : tensor<8x8xf64> {"llvm.noalias"}) -> tensor<8x8xf64> {
   // CHECK-NEXT:      return %{{.*}} : tensor<8x8xf64>
   // CHECK-NEXT:  }
+
+  func.func @output_attributes() -> (f32 {dialect.a = 0 : i32}, f32 {dialect.b = 0 : i32, dialect.c = 1 : i64}) {
+    %r1, %r2 = "test.op"() : () -> (f32, f32)
+    return %r1, %r2 : f32, f32
+  }
+
+  // CHECK:       func.func @output_attributes() -> (f32 {"dialect.a" = 0 : i32}, f32 {"dialect.b" = 0 : i32, "dialect.c" = 1 : i64}) {
+  // CHECK-NEXT:    %r1, %r2 = "test.op"() : () -> (f32, f32)
+  // CHECK-NEXT:    func.return %r1, %r2 : f32, f32
+  // CHECK-NEXT:  }
 }

tests/filecheck/dialects/func/func_ops_generic.mlir

@@ -10,3 +10,13 @@
 // CHECK-NEXT: ^0(%arg0 : tensor<8x8xf64>, %arg1 : tensor<8x8xf64>):
 // CHECK-NEXT: "func.return"(%arg0, %arg1) : (tensor<8x8xf64>, tensor<8x8xf64>) -> ()
 // CHECK-NEXT: }) : () -> ()
+
+func.func @output_attributes() -> (f32 {dialect.a = 0 : i32}, f32 {dialect.b = 0 : i32, dialect.c = 1 : i64}) {
+    %r1, %r2 = "test.op"() : () -> (f32, f32)
+    return %r1, %r2 : f32, f32
+}
+
+// CHECK:       "func.func"() <{"sym_name" = "output_attributes", "function_type" = () -> (f32, f32), "res_attrs" = [{"dialect.a" = 0 : i32}, {"dialect.b" = 0 : i32, "dialect.c" = 1 : i64}]}> ({
+// CHECK-NEXT:      %r1, %r2 = "test.op"() : () -> (f32, f32)
+// CHECK-NEXT:      "func.return"(%r1, %r2) : (f32, f32) -> ()
+// CHECK-NEXT:  }) : () -> ()

tests/filecheck/mlir-conversion/with-mlir/dialects/func/func_ops.mlir

@@ -72,4 +72,14 @@ builtin.module {
   // CHECK:       func.func public @arg_attrs(%{{.*}}: tensor<8x8xf64> {"llvm.noalias"}, %{{.*}}: tensor<8x8xf64> {"llvm.noalias"}, %{{.*}}: tensor<8x8xf64> {"llvm.noalias"}) -> tensor<8x8xf64> {
   // CHECK-NEXT:      func.return %{{.*}} : tensor<8x8xf64>
   // CHECK-NEXT:  }
+
+  func.func @output_attributes() -> (f32 {dialect.a = 0 : i32}, f32 {dialect.b = 0 : i32, dialect.c = 1 : i64}) {
+    %r1, %r2 = "test.op"() : () -> (f32, f32)
+    return %r1, %r2 : f32, f32
+  }
+
+  // CHECK:       func.func @output_attributes() -> (f32 {"dialect.a" = 0 : i32}, f32 {"dialect.b" = 0 : i32, "dialect.c" = 1 : i64}) {
+  // CHECK-NEXT:    %0, %1 = "test.op"() : () -> (f32, f32)
+  // CHECK-NEXT:    func.return %0, %1 : f32, f32
+  // CHECK-NEXT:  }
 }

xdsl/dialects/arm_func.py

@@ -83,18 +83,16 @@ def __init__(
     @classmethod
     def parse(cls, parser: Parser) -> FuncOp:
         visibility = parser.parse_optional_visibility_keyword()
-        (
-            name,
-            input_types,
-            return_types,
-            region,
-            extra_attrs,
-            arg_attrs,
-        ) = parse_func_op_like(
-            parser, reserved_attr_names=("sym_name", "function_type", "sym_visibility")
+        (name, input_types, return_types, region, extra_attrs, arg_attrs, res_attrs) = (
+            parse_func_op_like(
+                parser,
+                reserved_attr_names=("sym_name", "function_type", "sym_visibility"),
+            )
         )
         if arg_attrs:
-            raise NotImplementedError("arg_attrs not implemented in riscv_func")
+            raise NotImplementedError("arg_attrs not implemented in arm_func")
+        if res_attrs:
+            raise NotImplementedError("res_attrs not implemented in arm_func")
         func = FuncOp(name, region, (input_types, return_types), visibility)
         if extra_attrs is not None:
             func.attributes |= extra_attrs.data

xdsl/dialects/csl/csl.py

@@ -780,17 +780,16 @@ def verify_(self) -> None:
 
     @classmethod
     def parse(cls, parser: Parser) -> FuncOp:
-        (
-            name,
-            input_types,
-            return_types,
-            region,
-            extra_attrs,
-            arg_attrs,
-        ) = parse_func_op_like(
-            parser, reserved_attr_names=("sym_name", "function_type", "sym_visibility")
+        (name, input_types, return_types, region, extra_attrs, arg_attrs, res_attrs) = (
+            parse_func_op_like(
+                parser,
+                reserved_attr_names=("sym_name", "function_type", "sym_visibility"),
+            )
         )
 
+        if res_attrs:
+            raise NotImplementedError("res_attrs not implemented in csl FuncOp")
+
         assert (
             len(return_types) <= 1
         ), f"{cls.name} can't have more than one result type!"
@@ -890,16 +889,14 @@ def verify_(self) -> None:
     @classmethod
     def parse(cls, parser: Parser) -> TaskOp:
         pos = parser.pos
-        (
-            name,
-            input_types,
-            return_types,
-            region,
-            extra_attrs,
-            arg_attrs,
-        ) = parse_func_op_like(
-            parser, reserved_attr_names=("sym_name", "function_type", "sym_visibility")
+        (name, input_types, return_types, region, extra_attrs, arg_attrs, res_attrs) = (
+            parse_func_op_like(
+                parser,
+                reserved_attr_names=("sym_name", "function_type", "sym_visibility"),
+            )
         )
+        if res_attrs:
+            raise NotImplementedError("res_attrs not implemented in csl TaskOp")
         if (
             extra_attrs is None
             or "kind" not in extra_attrs.data

xdsl/dialects/func.py

@@ -166,6 +166,7 @@ def parse(cls, parser: Parser) -> FuncOp:
             region,
             extra_attrs,
             arg_attrs,
+            res_attrs,
         ) = parse_func_op_like(
             parser, reserved_attr_names=("sym_name", "function_type", "sym_visibility")
         )
@@ -175,6 +176,7 @@ def parse(cls, parser: Parser) -> FuncOp:
             region=region,
             visibility=visibility,
             arg_attrs=arg_attrs,
+            res_attrs=res_attrs,
         )
         if extra_attrs is not None:
             func.attributes |= extra_attrs.data
@@ -192,6 +194,7 @@ def print(self, printer: Printer):
             self.body,
             self.attributes,
             arg_attrs=self.arg_attrs,
+            res_attrs=self.res_attrs,
             reserved_attr_names=(
                 "sym_name",
                 "function_type",

xdsl/dialects/riscv_func.py

@@ -174,18 +174,16 @@ def __init__(
     @classmethod
     def parse(cls, parser: Parser) -> FuncOp:
         visibility = parser.parse_optional_visibility_keyword()
-        (
-            name,
-            input_types,
-            return_types,
-            region,
-            extra_attrs,
-            arg_attrs,
-        ) = parse_func_op_like(
-            parser, reserved_attr_names=("sym_name", "function_type", "sym_visibility")
+        (name, input_types, return_types, region, extra_attrs, arg_attrs, res_attrs) = (
+            parse_func_op_like(
+                parser,
+                reserved_attr_names=("sym_name", "function_type", "sym_visibility"),
+            )
         )
         if arg_attrs:
             raise NotImplementedError("arg_attrs not implemented in riscv_func")
+        if res_attrs:
+            raise NotImplementedError("res_attrs not implemented in riscv_func")
         func = FuncOp(name, region, (input_types, return_types), visibility)
         if extra_attrs is not None:
             func.attributes |= extra_attrs.data

xdsl/dialects/utils/format.py

@@ -43,6 +43,7 @@ def print_func_op_like(
     attributes: dict[str, Attribute],
     *,
     arg_attrs: ArrayAttr[DictionaryAttr] | None = None,
+    res_attrs: ArrayAttr[DictionaryAttr] | None = None,
     reserved_attr_names: Sequence[str],
 ):
     printer.print(f" @{sym_name.data}")
@@ -62,7 +63,15 @@ def print_func_op_like(
             printer.print("-> ")
             if len(function_type.outputs) > 1:
                 printer.print("(")
-            printer.print_list(function_type.outputs, printer.print_attribute)
+            if res_attrs is not None:
+                printer.print_list(
+                    zip(function_type.outputs, res_attrs),
+                    lambda arg_with_attrs: print_func_output(
+                        printer, arg_with_attrs[0], arg_with_attrs[1]
+                    ),
+                )
+            else:
+                printer.print_list(function_type.outputs, printer.print_attribute)
             if len(function_type.outputs) > 1:
                 printer.print(")")
             printer.print(" ")
@@ -85,9 +94,10 @@ def parse_func_op_like(
     Region,
     DictionaryAttr | None,
     ArrayAttr[DictionaryAttr] | None,
+    ArrayAttr[DictionaryAttr] | None,
 ]:
     """
-    Returns the function name, argument types, return types, body, extra args, and arg_attrs.
+    Returns the function name, argument types, return types, body, extra args, arg_attrs and res_attrs.
     """
     # Parse function name
     name = parser.parse_symbol_name().data
@@ -103,6 +113,13 @@ def parse_fun_input() -> Attribute | tuple[Parser.Argument, dict[str, Attribute]
             ret = (arg, arg_attr_dict)
         return ret
 
+    def parse_fun_output() -> tuple[Attribute, dict[str, Attribute]]:
+        arg_type = parser.parse_optional_type()
+        if arg_type is None:
+            parser.raise_error("Return type should be specified")
+        arg_attr_dict = parser.parse_optional_dictionary_attr_dict()
+        return (arg_type, arg_attr_dict)
+
     # Parse function arguments
     args = parser.parse_comma_separated_list(
         parser.Delimiter.PAREN,
@@ -135,14 +152,25 @@ def parse_fun_input() -> Attribute | tuple[Parser.Argument, dict[str, Attribute]
         arg_attrs = None
 
     # Parse return type
+    return_types: list[Attribute] = []
+    res_attrs_raw: list[dict[str, Attribute]] | None = []
     if parser.parse_optional_punctuation("->"):
-        return_types = parser.parse_optional_comma_separated_list(
-            parser.Delimiter.PAREN, parser.parse_type
+        return_attributes = parser.parse_optional_comma_separated_list(
+            parser.Delimiter.PAREN, parse_fun_output
         )
-        if return_types is None:
-            return_types = [parser.parse_type()]
+        if return_attributes is None:
+            # output attributes are supported only if return results are enclosed in brackets (...)
+            return_types, res_attrs_raw = [parser.parse_type()], None
+        else:
+            return_types, res_attrs_raw = (
+                [el[0] for el in return_attributes],
+                [el[1] for el in return_attributes],
+            )
+
+    if res_attrs_raw is not None and any(res_attrs_raw):
+        res_attrs = ArrayAttr(DictionaryAttr(attrs) for attrs in res_attrs_raw)
     else:
-        return_types = []
+        res_attrs = None
 
     extra_attributes = parser.parse_optional_attr_dict_with_keyword(reserved_attr_names)
 
@@ -151,7 +179,15 @@ def parse_fun_input() -> Attribute | tuple[Parser.Argument, dict[str, Attribute]
     if region is None:
         region = Region()
 
-    return name, input_types, return_types, region, extra_attributes, arg_attrs
+    return (
+        name,
+        input_types,
+        return_types,
+        region,
+        extra_attributes,
+        arg_attrs,
+        res_attrs,
+    )
 
 
 def print_func_argument(
@@ -162,6 +198,14 @@ def print_func_argument(
         printer.print_op_attributes(attrs.data)
 
 
+def print_func_output(
+    printer: Printer, out_type: Attribute, attrs: DictionaryAttr | None
+):
+    printer.print_attribute(out_type)
+    if attrs is not None and attrs.data:
+        printer.print_op_attributes(attrs.data)
+
+
 def print_assignment(printer: Printer, arg: BlockArgument, val: SSAValue):
     printer.print_block_argument(arg, print_type=False)
     printer.print_string(" = ")