core: replace BlockReverseOps with a Reversible conformance

xdsl/backend/riscv/register_allocation.py

@@ -197,7 +197,7 @@ def allocate_for_loop(self, loop: riscv_scf.ForOp) -> None:
             assert isinstance(iter_arg.type, IntRegisterType | FloatRegisterType)
             self.available_registers.reserve_register(iter_arg.type)
 
-        for op in loop.body.block.ops_reverse:
+        for op in reversed(loop.body.block.ops):
             self.process_operation(op)
 
         # Unreserve the loop carried variables for allocation outside of the body
@@ -260,7 +260,7 @@ def allocate_frep_loop(self, loop: riscv_snitch.FRepOperation) -> None:
             assert isinstance(iter_arg.type, IntRegisterType | FloatRegisterType)
             self.available_registers.reserve_register(iter_arg.type)
 
-        for op in loop.body.block.ops_reverse:
+        for op in reversed(loop.body.block.ops):
             self.process_operation(op)
 
         # Unreserve the loop carried variables for allocation outside of the body
@@ -299,7 +299,7 @@ def allocate_func(self, func: riscv_func.FuncOp) -> None:
 
         self.live_ins_per_block = live_ins_per_block(block)
         assert not self.live_ins_per_block[block]
-        for op in block.ops_reverse:
+        for op in reversed(block.ops):
             self.process_operation(op)
 
 
@@ -308,7 +308,7 @@ def _live_ins_per_block(
 ) -> OrderedSet[SSAValue]:
     res = OrderedSet[SSAValue]([])
 
-    for op in block.ops_reverse:
+    for op in reversed(block.ops):
         # Remove values defined in the block
         # We are traversing backwards, so cannot use the value removed here again
         res.difference_update(op.results)

xdsl/ir/core.py

@@ -2,7 +2,7 @@
 
 import re
 from abc import ABC, abstractmethod
-from collections.abc import Hashable, Iterable, Iterator, Mapping, Sequence
+from collections.abc import Hashable, Iterable, Iterator, Mapping, Reversible, Sequence
 from dataclasses import dataclass, field
 from io import StringIO
 from itertools import chain
@@ -1075,7 +1075,7 @@ def __format__(self, __format_spec: str) -> str:
 
 
 @dataclass
-class _BlockOpsIterator:
+class _BlockOpsIterator(Iterator[Operation]):
     """
     Single-pass iterable of the operations in a block. Follows the next_op for
     each operation.
@@ -1095,7 +1095,7 @@ def __next__(self):
 
 
 @dataclass
-class _BlockOpsReverseIterator:
+class _BlockOpsReverseIterator(Iterator[Operation]):
     """
     Single-pass iterable of the operations in a block. Follows the prev_op for
     each operation.
@@ -1115,7 +1115,7 @@ def __next__(self):
 
 
 @dataclass
-class BlockOps:
+class BlockOps(Reversible[Operation], Iterable[Operation]):
     """
     Multi-pass iterable of the operations in a block. Follows the next_op for
     each operation.
@@ -1136,6 +1136,9 @@ def __bool__(self) -> bool:
         """Returns `True` if there are operations in this block."""
         return not self.block.is_empty
 
+    def __reversed__(self):
+        return _BlockOpsReverseIterator(self.block.last_op)
+
     @property
     def first(self) -> Operation | None:
         """
@@ -1151,25 +1154,6 @@ def last(self) -> Operation | None:
         return self.block.last_op
 
 
-@dataclass
-class BlockReverseOps:
-    """
-    Multi-pass iterable of the operations in a block. Follows the prev_op for
-    each operation.
-    """
-
-    block: Block
-
-    def __iter__(self):
-        return _BlockOpsReverseIterator(self.block.last_op)
-
-    def __len__(self):
-        result = 0
-        for _ in self:
-            result += 1
-        return result
-
-
 @dataclass(init=False)
 class Block(IRNode):
     """A sequence of operations"""
@@ -1208,11 +1192,6 @@ def ops(self) -> BlockOps:
         """Returns a multi-pass Iterable of this block's operations."""
         return BlockOps(self)
 
-    @property
-    def ops_reverse(self) -> BlockReverseOps:
-        """Returns a multi-pass Iterable of this block's operations."""
-        return BlockReverseOps(self)
-
     def parent_op(self) -> Operation | None:
         return self.parent.parent if self.parent else None
 
@@ -1480,7 +1459,7 @@ def walk(
         operation. If reverse is set, then the region, block, and operation lists are
         iterated in reverse order.
         """
-        for op in self.ops_reverse if reverse else self.ops:
+        for op in reversed(self.ops) if reverse else self.ops:
             yield from op.walk(reverse=reverse, region_first=region_first)
 
     def verify(self) -> None:

xdsl/transforms/experimental/hls_convert_stencil_to_ll_mlir.py

@@ -624,7 +624,7 @@ def match_and_rewrite(self, op: ApplyOp, rewriter: PatternRewriter, /):
             new_return_op.detach()
             new_return_op.erase()
 
-            for operation in new_apply_block.ops_reverse:
+            for operation in reversed(new_apply_block.ops):
                 op_index = new_apply_block.get_operation_index(operation)
                 if op_index not in operation_indices:
                     operation.detach()