core: make VarOperand, VarOpResult, and VarRegion tuple instead of li…

…st (#2767)

Comes with some minimal impacts on uses, but seems like a win in terms
of communicating immutability.

tests/dialects/test_scf.py

@@ -51,7 +51,7 @@ def body(_: tuple[BlockArgument, ...]) -> None:
         step.result,
         carried.result,
     )
-    assert for_op.regions == [body]
+    assert for_op.regions == (body,)
     assert for_op.attributes == {}
 
     for_op.verify()
@@ -82,7 +82,7 @@ def body(_: tuple[BlockArgument, ...]) -> None:
         upper.result,
         step.result,
     )
-    assert for_op.regions == [body]
+    assert for_op.regions == (body,)
     assert for_op.attributes == {}
 
     for_op.verify()

tests/irdl/test_operation_builder.py

@@ -523,7 +523,7 @@ def test_two_var_region_builder():
     region4 = Region()
     op2 = TwoVarRegionOp.build(regions=[[region1, region2], [region3, region4]])
     op2.verify()
-    assert op2.regions == [region1, region2, region3, region4]
+    assert op2.regions == (region1, region2, region3, region4)
     assert op2.attributes[
         AttrSizedRegionSegments.attribute_name
     ] == DenseArrayBase.from_list(i32, [2, 2])
@@ -536,7 +536,7 @@ def test_two_var_operand_builder3():
     region4 = Region()
     op2 = TwoVarRegionOp.build(regions=[[region1], [region2, region3, region4]])
     op2.verify()
-    assert op2.regions == [region1, region2, region3, region4]
+    assert op2.regions == (region1, region2, region3, region4)
     assert op2.attributes[
         AttrSizedRegionSegments.attribute_name
     ] == DenseArrayBase.from_list(i32, [1, 3])

xdsl/ir/core.py

@@ -563,7 +563,7 @@ class Operation(IRNode):
     _operands: tuple[SSAValue, ...] = field(default=())
     """The operation operands."""
 
-    results: list[OpResult] = field(default_factory=list)
+    results: tuple[OpResult, ...] = field(default=())
     """The results created by the operation."""
 
     successors: list[Block] = field(default_factory=list)
@@ -582,7 +582,7 @@ class Operation(IRNode):
     attributes: dict[str, Attribute] = field(default_factory=dict)
     """The attributes attached to the operation."""
 
-    regions: list[Region] = field(default_factory=list)
+    regions: tuple[Region, ...] = field(default=())
     """Regions arguments of the operation."""
 
     parent: Block | None = field(default=None, repr=False)
@@ -696,14 +696,14 @@ def __init__(
         # This is assumed to exist by Operation.operand setter.
         self.operands = operands
 
-        self.results = [
+        self.results = tuple(
             OpResult(result_type, self, idx)
             for (idx, result_type) in enumerate(result_types)
-        ]
+        )
         self.properties = dict(properties)
         self.attributes = dict(attributes)
         self.successors = list(successors)
-        self.regions = []
+        self.regions = ()
         for region in regions:
             self.add_region(region)
 
@@ -738,7 +738,7 @@ def add_region(self, region: Region) -> None:
             raise Exception(
                 "Cannot add region that is already attached on an operation."
             )
-        self.regions.append(region)
+        self.regions += (region,)
         region.parent = self
 
     def get_region_index(self, region: Region) -> int:

xdsl/irdl/irdl.py

@@ -1004,7 +1004,7 @@ def __init__(
         self.constr = range_constr_coercion(attr)
 
 
-VarOperand: TypeAlias = list[SSAValue]
+VarOperand: TypeAlias = tuple[SSAValue, ...]
 
 
 @dataclass(init=False)
@@ -1038,7 +1038,7 @@ def __init__(
         self.constr = range_constr_coercion(attr)
 
 
-VarOpResult: TypeAlias = list[OpResult]
+VarOpResult: TypeAlias = tuple[OpResult, ...]
 
 
 @dataclass(init=False)
@@ -1068,7 +1068,7 @@ class OptRegionDef(RegionDef, OptionalDef):
     """An IRDL optional region definition."""
 
 
-VarRegion: TypeAlias = list[Region]
+VarRegion: TypeAlias = tuple[Region, ...]
 OptRegion: TypeAlias = Region | None
 
 
@@ -1839,7 +1839,7 @@ def get_construct_defs(
 
 def get_op_constructs(
     op: Operation, construct: VarIRConstruct
-) -> Sequence[SSAValue] | list[OpResult] | list[Region] | list[Successor]:
+) -> Sequence[SSAValue] | Sequence[OpResult] | Sequence[Region] | Sequence[Successor]:
     """
     Get the list of arguments of the type in an operation.
     For example, if the argument type is an operand, get the list of
@@ -2001,11 +2001,11 @@ def get_operand_result_or_region(
     None
     | SSAValue
     | Sequence[SSAValue]
-    | list[OpResult]
+    | Sequence[OpResult]
     | Region
-    | list[Region]
+    | Sequence[Region]
     | Successor
-    | list[Successor]
+    | Sequence[Successor]
 ):
     """
     Get an operand, result, or region.

xdsl/printer.py

@@ -349,7 +349,7 @@ def print_region(
         self._print_new_line()
         self.print("}")
 
-    def print_regions(self, regions: list[Region]) -> None:
+    def print_regions(self, regions: Sequence[Region]) -> None:
         if len(regions) == 0:
             return
 

xdsl/traits.py

@@ -213,7 +213,7 @@ class IsolatedFromAbove(OpTrait):
 
     def verify(self, op: Operation) -> None:
         # Start by checking all the passed operation's regions
-        regions: list[Region] = op.regions.copy()
+        regions: list[Region] = list(op.regions)
 
         # While regions are left to check
         while regions:

xdsl/transforms/experimental/lower_hls.py

@@ -339,7 +339,7 @@ def match_and_rewrite(self, op: ParallelOp, rewriter: PatternRewriter, /):
         # wrapping in for loops until we have exhausted the induction variables
         parallel_block = op.body.detach_block(0)
 
-        if res != []:
+        if res:
             parallel_block.insert_arg(res[0].type, 1)
             cast(Operation, parallel_block.last_op).detach()
             yieldop = Yield(res[0].op)
@@ -350,7 +350,7 @@ def match_and_rewrite(self, op: ParallelOp, rewriter: PatternRewriter, /):
         for i in range(len(lb) - 1):
             for_region.block.erase_arg(for_region.block.args[i])
 
-        if res != []:
+        if res:
             for_op = For(lb[-1], ub[-1], step[-1], [res[0].op], for_region)
         else:
             for_op = For(lb[-1], ub[-1], step[-1], [], for_region)

xdsl/transforms/lower_affine.py

@@ -1,3 +1,5 @@
+from collections.abc import Sequence
+
 from xdsl.context import MLContext
 from xdsl.dialects import affine, arith, builtin, memref, scf
 from xdsl.ir import Operation, SSAValue
@@ -20,8 +22,8 @@
 
 def affine_expr_ops(
     expr: affine.AffineExpr,
-    dims: list[SSAValue],
-    symbols: list[SSAValue],
+    dims: Sequence[SSAValue],
+    symbols: Sequence[SSAValue],
 ) -> tuple[list[Operation], SSAValue]:
     """
     Returns the operations that evaluate the affine expression when given input SSA
@@ -59,7 +61,7 @@ def affine_expr_ops(
 
 def insert_affine_map_ops(
     map: affine.AffineMapAttr | None,
-    dims: list[SSAValue],
+    dims: Sequence[SSAValue],
     symbols: list[SSAValue],
 ) -> tuple[list[Operation], list[SSAValue]]:
     """
@@ -68,7 +70,7 @@ def insert_affine_map_ops(
     """
     ops: list[Operation] = []
     if map is None:
-        indices = dims
+        indices = list(dims)
     else:
         indices: list[SSAValue] = []
         for expr in map.data.results:

xdsl/transforms/lower_riscv_func.py

@@ -46,7 +46,7 @@ def match_and_rewrite(self, op: riscv_func.SyscallOp, rewriter: PatternRewriter)
 
         if op.result is None:
             ops.append(riscv.EcallOp())
-            new_results = []
+            new_results = ()
         else:
             # The result will be stored to a0, move to register that will be used
             ecall = riscv.EcallOp()