[MLIR][SCF] Add dedicated Python bindings for ForallOp

mlir/python/mlir/dialects/scf.py

@@ -17,7 +17,7 @@
 except ImportError as e:
     raise RuntimeError("Error loading imports from extension module") from e
 
-from typing import Optional, Sequence, Union
+from typing import List, Optional, Sequence, Tuple, Union
 
 
 @_ods_cext.register_operation(_Dialect, replace=True)
@@ -71,6 +71,120 @@ def inner_iter_args(self):
         return self.body.arguments[1:]
 
 
+def dispatch_index_op_fold_results(
+    ofrs: Sequence[Union[int, Value]],
+) -> Tuple[List[Value], List[int]]:
+    """`mlir::dispatchIndexOpFoldResults`"""
+    dynamic_vals = []
+    static_vals = []
+    for ofr in ofrs:
+        if isinstance(ofr, Value):
+            dynamic_vals.append(ofr)
+            static_vals.append(ShapedType.get_dynamic_size())
+        else:
+            static_vals.append(ofr)
+    return dynamic_vals, static_vals
+
+
+@_ods_cext.register_operation(_Dialect, replace=True)
+class ForallOp(ForallOp):
+    """Specialization for the SCF forall op class."""
+
+    def __init__(
+        self,
+        lower_bounds: Sequence[Union[Value, int]],
+        upper_bounds: Sequence[Union[Value, int]],
+        steps: Sequence[Union[Value, int]],
+        iter_args: Optional[Union[Operation, OpView, Sequence[Value]]] = None,
+        *,
+        mapping=None,
+        loc=None,
+        ip=None,
+    ):
+        """Creates an SCF `forall` operation.
+
+        - `lower_bounds` are the values to use as lower bounds of the loop.
+        - `upper_bounds` are the values to use as upper bounds of the loop.
+        - `steps` are the values to use as loop steps.
+        - `iter_args` is a list of additional loop-carried arguments or an operation
+          producing them as results.
+        """
+        if iter_args is None:
+            iter_args = []
+        iter_args = _get_op_results_or_values(iter_args)
+
+        dynamic_lbs, static_lbs = dispatch_index_op_fold_results(lower_bounds)
+        dynamic_ubs, static_ubs = dispatch_index_op_fold_results(upper_bounds)
+        dynamic_steps, static_steps = dispatch_index_op_fold_results(steps)
+
+        results = [arg.type for arg in iter_args]
+        super().__init__(
+            results,
+            dynamic_lbs,
+            dynamic_ubs,
+            dynamic_steps,
+            static_lbs,
+            static_ubs,
+            static_steps,
+            iter_args,
+            mapping=mapping,
+            loc=loc,
+            ip=ip,
+        )
+        rank = len(static_lbs)
+        iv_types = [IndexType.get()] * rank
+        self.regions[0].blocks.append(*iv_types, *results)
+
+    @property
+    def body(self) -> Block:
+        """Returns the body (block) of the loop."""
+        return self.regions[0].blocks[0]
+
+    @property
+    def rank(self) -> int:
+        """Returns the number of induction variables the loop has."""
+        return len(self.staticLowerBound)
+
+    @property
+    def induction_variables(self) -> BlockArgumentList:
+        """Returns the induction variables usable within the loop."""
+        return self.body.arguments[: self.rank]
+
+    @property
+    def inner_iter_args(self):
+        """Returns the loop-carried arguments usable within the loop.
+
+        To obtain the loop-carried operands, use `iter_args`.
+        """
+        return self.body.arguments[self.rank :]
+
+    @property
+    def terminator(self) -> InParallelOp:
+        """
+        Returns the loop terminator if it exists.
+        Otherwise, create a new one.
+        """
+        ops = self.body.operations
+        with InsertionPoint(self.body):
+            if not ops:
+                return InParallelOp()
+            last = ops[len(ops) - 1]
+            return last if isinstance(last, InParallelOp) else InParallelOp()
+
+
+@_ods_cext.register_operation(_Dialect, replace=True)
+class InParallelOp(InParallelOp):
+    """Specialization of the SCF forall.in_parallel op class."""
+
+    def __init__(self, loc=None, ip=None):
+        super().__init__(loc=loc, ip=ip)
+        self.region.blocks.append()
+
+    @property
+    def block(self) -> Block:
+        return self.region.blocks[0]
+
+
 @_ods_cext.register_operation(_Dialect, replace=True)
 class IfOp(IfOp):
     """Specialization for the SCF if op class."""

mlir/test/python/dialects/scf.py

@@ -18,6 +18,26 @@ def constructAndPrintInModule(f):
     return f
 
 
+# CHECK-LABEL: TEST: testSimpleForall
+# CHECK: scf.forall (%[[IV0:.*]], %[[IV1:.*]]) in (4, 8) shared_outs(%[[BOUND_ARG:.*]] = %{{.*}}) -> (tensor<4x8xf32>)
+# CHECK:   arith.addi %[[IV0]], %[[IV1]]
+# CHECK:   scf.forall.in_parallel
+@constructAndPrintInModule
+def testSimpleForall():
+    f32 = F32Type.get()
+    tensor_type = RankedTensorType.get([4, 8], f32)
+
+    @func.FuncOp.from_py_func(tensor_type)
+    def forall_loop(tensor):
+        loop = scf.ForallOp([0, 0], [4, 8], [1, 1], [tensor])
+        with InsertionPoint(loop.body):
+            i, j = loop.induction_variables
+            arith.addi(i, j)
+            loop.terminator
+        # The verifier will check that the regions have been created properly.
+        assert loop.verify()
+
+
 # CHECK-LABEL: TEST: testSimpleLoop
 @constructAndPrintInModule
 def testSimpleLoop():