Simplify codegen for hl.grid

This makes codegen for grids go down the standard SymInt codegen path.

Author: jansel

helion/_compiler/compile_environment.py

@@ -422,9 +422,6 @@ def is_flattened(self, config: Config) -> bool:
         spec = CompileEnvironment.current().config_spec
         return spec.flatten_loops.config_get(config.flatten_loops, self.block_id, False)
 
-    def is_grid(self) -> bool:
-        return self.block_size_source.is_grid()
-
     def update_min_block(self, value: int, *, allow_flattened: bool = True) -> None:
         spec = CompileEnvironment.current().config_spec
         if not allow_flattened:
@@ -437,9 +434,6 @@ class BlockSizeSource:
     def from_config(self, config: Config, block_id: int) -> int | torch.SymInt | None:
         raise NotImplementedError
 
-    def is_grid(self) -> bool:
-        return False
-
     def l2_grouping(self, config: Config) -> int:
         return 1
 
@@ -452,17 +446,6 @@ def from_config(self, config: Config, block_id: int) -> int | torch.SymInt:
         return self.value
 
 
-@dataclasses.dataclass
-class GridBlockSizeSource(BlockSizeSource):
-    """Block size source for grid indices - always has block_size=1 but marks as grid for special indexing"""
-
-    def from_config(self, config: Config, block_id: int) -> int:
-        return 1
-
-    def is_grid(self) -> bool:
-        return True
-
-
 @dataclasses.dataclass
 class LoopSpecBlockSizeSource(BlockSizeSource):
     def from_config(self, config: Config, block_id: int) -> int:

helion/_compiler/device_function.py

@@ -31,11 +31,13 @@
 from .host_function import NoCurrentFunction
 from .output_header import reserved_names
 from .variable_origin import BlockSizeOrigin
+from .variable_origin import GridOrigin
 from .variable_origin import Origin
 from .variable_origin import TensorSizeOrigin
 
 if TYPE_CHECKING:
     from ..runtime.config import Config
+    from .generate_ast import GenerateAST
     from .program_id import ProgramIDs
     from .program_id import SharedProgramID
 
@@ -136,10 +138,11 @@ def __init__(self, val: int) -> None:
 
 
 class DeviceFunction:
-    def __init__(self, name: str, config: Config) -> None:
+    def __init__(self, name: str, config: Config, codegen: GenerateAST) -> None:
         super().__init__()
         self.name = name
         self.config = config
+        self.codegen = codegen
         self.arguments: list[Argument] = []
         self.body: list[ast.AST] = []
         self._tensor_args: dict[torch.Tensor, TensorArg] = {}
@@ -219,6 +222,8 @@ def _lift_sympy_arg(self, expr: sympy.Expr) -> str:
             result = self.block_size_var(origin.origin.block_id)
             assert result is not None
             return result
+        if isinstance(origin.origin, GridOrigin):
+            return self.codegen.offset_var(origin.origin.block_id)
         return self.expr_arg(expr, origin.origin).name
 
     def user_sympy_expr(self, expr: sympy.Expr) -> str:

helion/_compiler/device_ir.py

@@ -40,6 +40,7 @@
 from .ast_read_writes import ReadWrites
 from .compile_environment import CompileEnvironment
 from .host_function import HostFunction
+from .inductor_lowering import APIFuncLowering
 from .inductor_lowering import CodegenState
 from .inductor_lowering import codegen_call_with_graph
 from .inductor_lowering import prepare_graph_lowerings
@@ -98,6 +99,7 @@ def _get_proxy_slot(
                     name=origin.suggest_var_name(),
                 )
                 proxy.node.meta["val"] = obj
+                proxy.node.meta["lowering"] = APIFuncLowering(_tracing_ops._host_tensor)
             return transform(tracker[obj])
         if isinstance(obj, proxy_tensor.py_sym_types):
             tracker = tracer.symnode_tracker
@@ -111,6 +113,7 @@ def _get_proxy_slot(
                     name=debug_name if debug_name.isidentifier() else "symnode",
                 )
                 proxy.node.meta["val"] = obj
+                proxy.node.meta["lowering"] = APIFuncLowering(_tracing_ops._get_symnode)
                 proxy.force = lambda: proxy
             return transform(tracker[obj])
         return get_proxy_slot(obj, tracer, default, transform)

helion/_compiler/generate_ast.py

@@ -39,7 +39,7 @@ def __init__(self, func: HostFunction, config: Config) -> None:
         self.host_statements: list[ast.AST] = []
         self.statements_stack: list[list[ast.AST]] = [self.host_statements]
         self.on_device = False
-        self.device_function = DeviceFunction(f"_{func.name}_kernel", config)
+        self.device_function = DeviceFunction(f"_{func.name}_kernel", config, self)
         self.active_device_loops: dict[int, list[DeviceLoopOrGridState]] = (
             collections.defaultdict(list)
         )
@@ -404,7 +404,7 @@ def generate_ast(func: HostFunction, config: Config) -> ast.AST:
             precompile_def = codegen_precompile_def(
                 host_def, codegen.device_function.name
             )
-            return ast.Module(
+            result = ast.Module(
                 [
                     *func.codegen_imports(),
                     kernel_def,
@@ -413,3 +413,6 @@ def generate_ast(func: HostFunction, config: Config) -> ast.AST:
                 ],
                 [],
             )
+            # break circular reference for better GC
+            del codegen.device_function.codegen
+            return result

helion/_compiler/indexing_strategy.py

@@ -218,9 +218,7 @@ def compute_shape(
                 if isinstance(symbol, sympy.Symbol):
                     origin = HostFunction.current().expr_to_origin.get(symbol)
                     if origin and isinstance(origin.origin, BlockSizeOrigin):
-                        if env.block_sizes[origin.origin.block_id].is_grid():
-                            pass
-                        elif tensor.size(tensor.ndim - len(input_size) - 1) != 1:
+                        if tensor.size(tensor.ndim - len(input_size) - 1) != 1:
                             output_size.append(k)
                         else:
                             output_size.append(1)
@@ -267,9 +265,6 @@ def create(
                     origin = HostFunction.current().expr_to_origin.get(symbol)
                 if origin and isinstance(origin.origin, BlockSizeOrigin):
                     index_var = state.codegen.index_var(origin.origin.block_id)
-                    if env.block_sizes[origin.origin.block_id].is_grid():
-                        index_values.append(index_var)
-                        continue
                     expand = tile_strategy.expand_str(output_size, output_idx)
                     i = len(index_values)
                     index_values.append(f"({index_var}){expand}")

helion/_compiler/type_propagation.py

@@ -45,6 +45,7 @@
 from .variable_origin import DeviceOrigin
 from .variable_origin import GetItemOrigin
 from .variable_origin import GlobalOrigin
+from .variable_origin import GridOrigin
 from .variable_origin import Origin
 from .variable_origin import SourceOrigin
 from .variable_origin import TensorSizeOrigin
@@ -1023,11 +1024,8 @@ def propagate_attribute(self, attr: str, origin: AttributeOrigin) -> TypeInfo:
 class GridIndexType(SymIntType):
     block_id: int
 
-    def __init__(self, origin: Origin, block_id: int) -> None:
-        from .._compiler.compile_environment import CompileEnvironment
-
-        env = CompileEnvironment.current()
-        super().__init__(origin, env.block_sizes[block_id].var)
+    def __init__(self, origin: Origin, sym: torch.SymInt, block_id: int) -> None:
+        super().__init__(origin, sym)
         self.block_id = block_id
 
     def __str__(self) -> str:  # pragma: no cover – debug helper
@@ -1036,11 +1034,17 @@ def __str__(self) -> str:  # pragma: no cover – debug helper
     @staticmethod
     def allocate(numel: int | torch.SymInt, origin: Origin) -> GridIndexType:
         from .._compiler.compile_environment import CompileEnvironment
-        from .._compiler.compile_environment import GridBlockSizeSource
+        from .host_function import HostFunction
+        from .host_function import SymbolOrigin
 
         env = CompileEnvironment.current()
-        block_idx = env.allocate_block_size(numel, source=GridBlockSizeSource())
-        return GridIndexType(origin, block_idx)
+        block_id = env.allocate_block_size(numel, source=FixedBlockSizeSource(1))
+        # assign this a new unbacked symbol since this should be treated like a scalar rather than a tile
+        sym = env.create_unbacked_symint()
+        HostFunction.current().expr_to_origin[sym._sympy_()] = SymbolOrigin(
+            origin=GridOrigin(block_id),
+        )
+        return GridIndexType(origin, sym, block_id)
 
     def merge(self, other: TypeInfo) -> TypeInfo:  # type: ignore[override]
         if isinstance(other, GridIndexType):

helion/_compiler/variable_origin.py

@@ -247,3 +247,13 @@ class ReductionDimensionOrigin(Origin):
 
     def host_str(self) -> str:
         raise NotImplementedError
+
+
+@dataclasses.dataclass
+class GridOrigin(Origin):
+    """Note this represents the tile_begin() of the grid, not the block size (which is always 1)"""
+
+    block_id: int
+
+    def host_str(self) -> str:
+        raise NotImplementedError

test/test_control_flow.py

@@ -123,21 +123,20 @@ def fn(x: torch.Tensor, y: torch.Tensor) -> torch.Tensor:
 def _fn_kernel(x, y, output, output_stride_0, x_stride_0, y_stride_0):
     pid_0 = tl.program_id(0)
     offset_0 = pid_0
-    indices_0 = offset_0 + tl.zeros([1], tl.int32)
-    load = tl.load(y + indices_0 * y_stride_0, None)
+    load = tl.load(y + tl.full([1], offset_0, tl.int32) * y_stride_0, None)
     v_0 = tl.full([], 0, tl.int32)
     v_1 = load != v_0
     if tl.sum(v_1):
-        load_1 = tl.load(x + indices_0 * x_stride_0, None)
+        load_1 = tl.load(x + tl.full([1], offset_0, tl.int32) * x_stride_0, None)
         v_2 = 2.0
         v_3 = load_1 * v_2
-        tl.store(output + indices_0 * output_stride_0, v_3, None)
-    load_2 = tl.load(y + indices_0 * y_stride_0, None)
+        tl.store(output + tl.full([1], offset_0, tl.int32) * output_stride_0, v_3, None)
+    load_2 = tl.load(y + tl.full([1], offset_0, tl.int32) * y_stride_0, None)
     v_4 = tl.full([], 0, tl.int32)
     v_5 = load_2 == v_4
     if tl.sum(v_5):
-        load_3 = tl.load(x + indices_0 * x_stride_0, None)
-        tl.store(output + indices_0 * output_stride_0, load_3, None)
+        load_3 = tl.load(x + tl.full([1], offset_0, tl.int32) * x_stride_0, None)
+        tl.store(output + tl.full([1], offset_0, tl.int32) * output_stride_0, load_3, None)
 
 def fn(x: torch.Tensor, y: torch.Tensor):
     output = torch.zeros_like(x)

test/test_examples.py

@@ -1687,9 +1687,8 @@ def test_moe_matmul_ogs(self):
 def _moe_matmul_ogs_kernel(expert_token_offsets, expert_token_counts, sorted_to_orig_token_idx, A, W, C, A_stride_0, A_stride_1, C_stride_0, C_stride_1, W_stride_0, W_stride_1, W_stride_2, expert_token_counts_stride_0, expert_token_offsets_stride_0, sorted_to_orig_token_idx_stride_0, max_T_per_expert, N, K, _BLOCK_SIZE_2: tl.constexpr, _BLOCK_SIZE_1: tl.constexpr, _BLOCK_SIZE_3: tl.constexpr):
     pid_0 = tl.program_id(0)
     offset_0 = pid_0
-    indices_0 = offset_0 + tl.zeros([1], tl.int32)
-    start = tl.load(expert_token_offsets + indices_0 * expert_token_offsets_stride_0, None)
-    num_tokens = tl.load(expert_token_counts + indices_0 * expert_token_counts_stride_0, None)
+    start = tl.load(expert_token_offsets + tl.full([1], offset_0, tl.int32) * expert_token_offsets_stride_0, None)
+    num_tokens = tl.load(expert_token_counts + tl.full([1], offset_0, tl.int32) * expert_token_counts_stride_0, None)
     v_0 = tl.full([], 0, tl.int32)
     v_1 = num_tokens != v_0
     if tl.sum(v_1):
@@ -1725,7 +1724,7 @@ def _moe_matmul_ogs_kernel(expert_token_offsets, expert_token_counts, sorted_to_
                     expert_orig_token_indices_copy_0 = expert_orig_token_indices_copy
                     acc_copy_0 = acc_copy
                     A_frag = tl.load(A + (expert_orig_token_indices_copy_0[:, None] * A_stride_0 + indices_3[None, :] * A_stride_1), mask_1[:, None] & mask_3[None, :], other=0)
-                    W_frag = tl.load(W + (indices_0 * W_stride_0 + indices_3[:, None] * W_stride_1 + indices_2[None, :] * W_stride_2), mask_3[:, None] & mask_2[None, :], other=0)
+                    W_frag = tl.load(W + (tl.full([1], offset_0, tl.int32)[:, None] * W_stride_0 + indices_3[:, None] * W_stride_1 + indices_2[None, :] * W_stride_2), mask_3[:, None] & mask_2[None, :], other=0)
                     acc = tl.dot(A_frag, W_frag, acc=acc_copy_0, input_precision='tf32')
                 existing_values = tl.load(C + (expert_orig_token_indices[:, None] * C_stride_0 + indices_2[None, :] * C_stride_1), mask_1[:, None] & mask_2[None, :], other=0)
                 view = tl.reshape(v_3, [_BLOCK_SIZE_1, 1])