fix[next][dace]: Fixes to DaCe backend to support latest ITIR (#1499)

Fixes in DaCe backend to support latest ITIR:

- Add support for tuple argument to lambda functions.
- Flatten list of expressions in if-statememts

Minor code cleanup: skip debug information for memlets.

src/gt4py/next/program_processors/runners/dace_iterator/itir_to_tasklet.py

@@ -401,7 +401,7 @@ def builtin_neighbors(
         origin_index_node,
         me,
         shift_tasklet,
-        memlet=dace.Memlet(data=origin_index_node.data, subset="0", debuginfo=di),
+        memlet=dace.Memlet(data=origin_index_node.data, subset="0"),
         dst_conn="__idx",
     )
     state.add_edge(
@@ -469,7 +469,7 @@ def builtin_neighbors(
             data_access_tasklet,
             mx,
             neighbor_value_node,
-            memlet=dace.Memlet(data=neighbor_value_var, subset=neighbor_map_index, debuginfo=di),
+            memlet=dace.Memlet(data=neighbor_value_var, subset=neighbor_map_index),
             src_conn="__data",
         )
 
@@ -496,6 +496,7 @@ def builtin_neighbors(
             {"__idx"},
             {"__valid"},
             f"__valid = True if __idx != {neighbor_skip_value} else False",
+            debuginfo=di,
         )
         state.add_edge(
             neighbor_index_node,
@@ -545,7 +546,7 @@ def builtin_can_deref(
             "_out",
             result_node,
             None,
-            dace.Memlet(data=result_name, subset="0", debuginfo=di),
+            dace.Memlet(data=result_name, subset="0"),
         )
         return [ValueExpr(result_node, dace.dtypes.bool)]
 
@@ -598,14 +599,14 @@ def build_if_state(arg, state):
         stmt_state, tbr_state, dace.InterstateEdge(condition=f"{stmt_node.value.data} == True")
     )
     sdfg.add_edge(tbr_state, join_state, dace.InterstateEdge())
-    tbr_values = build_if_state(node_args[1], tbr_state)
+    tbr_values = flatten_list(build_if_state(node_args[1], tbr_state))
     #
     fbr_state = sdfg.add_state("false_branch")
     sdfg.add_edge(
         stmt_state, fbr_state, dace.InterstateEdge(condition=f"{stmt_node.value.data} == False")
     )
     sdfg.add_edge(fbr_state, join_state, dace.InterstateEdge())
-    fbr_values = build_if_state(node_args[2], fbr_state)
+    fbr_values = flatten_list(build_if_state(node_args[2], fbr_state))
 
     assert isinstance(stmt_node, ValueExpr)
     assert stmt_node.dtype == dace.dtypes.bool
@@ -804,7 +805,7 @@ def builtin_tuple_get(
 class GatherLambdaSymbolsPass(eve.NodeVisitor):
     _sdfg: dace.SDFG
     _state: dace.SDFGState
-    _symbol_map: dict[str, TaskletExpr]
+    _symbol_map: dict[str, TaskletExpr | tuple[ValueExpr]]
     _parent_symbol_map: dict[str, TaskletExpr]
 
     def __init__(
@@ -827,7 +828,7 @@ def _add_symbol(self, param, arg):
         if isinstance(arg, ValueExpr):
             # create storage in lambda sdfg
             self._sdfg.add_scalar(param, dtype=arg.dtype)
-            # update table of lambda symbol
+            # update table of lambda symbols
             self._symbol_map[param] = ValueExpr(
                 self._state.add_access(param, debuginfo=self._sdfg.debuginfo), arg.dtype
             )
@@ -839,7 +840,7 @@ def _add_symbol(self, param, arg):
             index_names = {dim: f"__{param}_i_{dim}" for dim in arg.indices.keys()}
             for _, index_name in index_names.items():
                 self._sdfg.add_scalar(index_name, dtype=_INDEX_DTYPE)
-            # update table of lambda symbol
+            # update table of lambda symbols
             field = self._state.add_access(param, debuginfo=self._sdfg.debuginfo)
             indices = {
                 dim: self._state.add_access(index_arg, debuginfo=self._sdfg.debuginfo)
@@ -850,6 +851,17 @@ def _add_symbol(self, param, arg):
             assert isinstance(arg, SymbolExpr)
             self._symbol_map[param] = arg
 
+    def _add_tuple(self, param, args):
+        nodes = []
+        # create storage in lambda sdfg for each tuple element
+        for arg in args:
+            var = unique_var_name()
+            self._sdfg.add_scalar(var, dtype=arg.dtype)
+            arg_node = self._state.add_access(var, debuginfo=self._sdfg.debuginfo)
+            nodes.append(ValueExpr(arg_node, arg.dtype))
+        # update table of lambda symbols
+        self._symbol_map[param] = tuple(nodes)
+
     def visit_SymRef(self, node: itir.SymRef):
         name = str(node.id)
         if name in self._parent_symbol_map and name not in self._symbol_map:
@@ -858,9 +870,13 @@ def visit_SymRef(self, node: itir.SymRef):
 
     def visit_Lambda(self, node: itir.Lambda, args: Optional[Sequence[TaskletExpr]] = None):
         if args is not None:
-            assert len(node.params) == len(args)
-            for param, arg in zip(node.params, args):
-                self._add_symbol(str(param.id), arg)
+            if len(node.params) == len(args):
+                for param, arg in zip(node.params, args):
+                    self._add_symbol(str(param.id), arg)
+            else:
+                # implicitly make tuple
+                assert len(node.params) == 1
+                self._add_tuple(str(node.params[0].id), args)
         self.visit(node.expr)
 
 
@@ -937,7 +953,7 @@ def visit_Lambda(
         # Create the SDFG for the lambda's body
         lambda_sdfg = dace.SDFG(func_name)
         lambda_sdfg.debuginfo = dace_debuginfo(node, self.context.body.debuginfo)
-        lambda_state = lambda_sdfg.add_state(f"{func_name}_entry", True)
+        lambda_state = lambda_sdfg.add_state(f"{func_name}_body", is_start_block=True)
 
         lambda_symbols_pass = GatherLambdaSymbolsPass(
             lambda_sdfg, lambda_state, self.context.symbol_map
@@ -947,9 +963,13 @@ def visit_Lambda(
         # Add for input nodes for lambda symbols
         inputs: list[tuple[str, ValueExpr] | tuple[tuple[str, dict], IteratorExpr]] = []
         for sym, input_node in lambda_symbols_pass.symbol_refs.items():
-            arg = next((arg for param, arg in zip(node.params, args) if param.id == sym), None)
-            if arg:
-                outer_node = arg
+            params = [str(p.id) for p in node.params]
+            try:
+                param_index = params.index(sym)
+            except ValueError:
+                param_index = -1
+            if param_index >= 0:
+                outer_node = args[param_index]
             else:
                 # the symbol is not found among lambda arguments, then it is inherited from parent scope
                 outer_node = self.context.symbol_map[sym]
@@ -962,6 +982,13 @@ def visit_Lambda(
             elif isinstance(input_node, ValueExpr):
                 assert isinstance(outer_node, ValueExpr)
                 inputs.append((sym, outer_node))
+            elif isinstance(input_node, tuple):
+                assert param_index >= 0
+                for i, input_node_i in enumerate(input_node):
+                    arg_i = args[param_index + i]
+                    assert isinstance(arg_i, ValueExpr)
+                    assert isinstance(input_node_i, ValueExpr)
+                    inputs.append((input_node_i.value.data, arg_i))
 
         # Add connectivities as arrays
         for name in connectivity_names:
@@ -1530,7 +1557,7 @@ def add_expr_tasklet(
                 )
                 self.context.state.add_edge(arg.value, None, expr_tasklet, internal, memlet)
 
-        memlet = dace.Memlet(data=result_access.data, subset="0", debuginfo=di)
+        memlet = dace.Memlet(data=result_access.data, subset="0")
         self.context.state.add_edge(expr_tasklet, "__result", result_access, None, memlet)
 
         return [ValueExpr(result_access, result_type)]