Add tl.range loop_unroll_factor to autotuner

README.md

@@ -191,6 +191,10 @@ allowing you to permute the iteration order of the tiles.
 Contains one entry per `hl.tile` call with two or more dimensions,
 allowing you to flatten the iteration space into a single dimension.
 
+* **range\_unroll\_factors** (`list[int]`):
+Contains one entry per loop dimension, specifying the unroll factor for
+`tl.range()` calls. Values less than 1 omit the `loop_unroll_factor` parameter.
+
 * **reduction\_loops** (`list[int | None]`):
 Contains one entry per reduction dimension (see
 `examples/softmax.py`). Using `None` triggers a persistent reduction,

helion/_compiler/reduction_strategy.py

@@ -252,11 +252,13 @@ def codegen_device_loop(self, state: CodegenState) -> DeviceLoopState:
                     f"{mask_var} = {index_var} < {state.sympy_expr(numel)}"
                 )
             )
+
+        range_extra = self.get_tl_range_kwargs(state, self.block_index)
         for_node = create(
             ast.For,
             target=create(ast.Name, id=offset_var, ctx=ast.Store()),
             iter=expr_from_string(
-                f"range(0, ({state.sympy_expr(numel)}), {block_size_var})"
+                f"tl.range(0, ({state.sympy_expr(numel)}), {block_size_var}{range_extra})"
             ),
             body=body,
             orelse=[],

helion/_compiler/tile_strategy.py

@@ -123,6 +123,16 @@ def mask_var(self, block_idx: int) -> str | None:
     def block_size_var(self, block_idx: int) -> str | None:
         return self.fn.block_size_var_cache.get((block_idx,))
 
+    def get_tl_range_kwargs(self, state: CodegenState, block_idx: int) -> str:
+        """Get the range_extra string for loop unroll factor based on config."""
+        env = CompileEnvironment.current()
+        range_unroll_factor = env.config_spec.range_unroll_factors.config_get(
+            state.config.range_unroll_factors, block_idx, 0
+        )
+        if range_unroll_factor > 0:
+            return f", loop_unroll_factor={range_unroll_factor}"
+        return ""
+
     def user_size(self, block_index: int) -> sympy.Expr:
         raise NotImplementedError
 
@@ -360,11 +370,12 @@ def codegen_device_loop(self, state: CodegenState) -> DeviceLoopState:
         )
         dtype = CompileEnvironment.current().triton_index_type()
         lid = self.new_var("lid")
+        range_extra = self.get_tl_range_kwargs(state, self.block_ids[0])
         for_node = create(
             ast.For,
             target=create(ast.Name, id=lid, ctx=ast.Store()),
             iter=expr_from_string(
-                f"range(tl.cdiv({state.sympy_expr(total_numel)}, {block_size_var}))"
+                f"tl.range(tl.cdiv({state.sympy_expr(total_numel)}, {block_size_var}){range_extra})"
             ),
             body=(
                 body := [
@@ -568,11 +579,13 @@ def codegen_device_loop(self, state: CodegenState) -> DeviceLoopState:
                 end_var_name=end_var_name,
                 end_expr=self._fold_tile_end_op(state, proxy_end, block_size),
             )
+
+            range_extra = self.get_tl_range_kwargs(state, block_idx)
             for_node = create(
                 ast.For,
                 target=create(ast.Name, id=offset_var, ctx=ast.Store()),
                 iter=expr_from_string(
-                    f"range(begin, end, {block_size_var})",
+                    f"tl.range(begin, end, {block_size_var}{range_extra})",
                     begin=self._to_ast(begin, to_dtype=dtype),
                     end=self._to_ast(end, to_dtype=dtype),
                 ),

helion/autotuner/config_spec.py

@@ -36,6 +36,7 @@
         "l2_groupings",
         "reduction_loops",
         "flatten_loops",
+        "range_unroll_factors",
         "num_warps",
         "num_stages",
         "use_yz_grid",
@@ -61,6 +62,9 @@ class ConfigSpec:
     reduction_loops: BlockIdSequence[ReductionLoopSpec] = dataclasses.field(
         default_factory=BlockIdSequence
     )
+    range_unroll_factors: BlockIdSequence[RangeUnrollFactorSpec] = dataclasses.field(
+        default_factory=BlockIdSequence
+    )
     user_defined_tunables: dict[str, ConfigSpecFragment] = dataclasses.field(
         default_factory=dict
     )
@@ -70,6 +74,7 @@ def _remove_duplicates(self) -> None:
         self.loop_orders._remove_duplicates()
         self.l2_groupings._remove_duplicates()
         self.flatten_loops._remove_duplicates()
+        self.range_unroll_factors._remove_duplicates()
 
     def normalize(self, config: helion.Config | dict[str, object]) -> None:
         """Normalize the config to match the block_sizes and validate the config."""
@@ -83,6 +88,7 @@ def normalize(self, config: helion.Config | dict[str, object]) -> None:
             "reduction_loop",
             "l2_grouping",
             "flatten_loop",
+            "range_unroll_factor",
         ):
             if name in config:
                 names = f"{name}s"
@@ -96,12 +102,19 @@ def normalize(self, config: helion.Config | dict[str, object]) -> None:
             ("l2_groupings", self.l2_groupings, True),
             ("loop_orders", self.loop_orders, False),
             ("reduction_loops", self.reduction_loops, True),
+            ("range_unroll_factors", self.range_unroll_factors, True),
         ]:
             config[name] = mapping._normalize(
                 name, config.get(name, ()), flatten=flatten
             )
 
-        for name in ("loop_orders", "l2_groupings", "flatten_loops", "reduction_loops"):
+        for name in (
+            "loop_orders",
+            "l2_groupings",
+            "flatten_loops",
+            "reduction_loops",
+            "range_unroll_factors",
+        ):
             if not config[name]:
                 config.pop(name)
 
@@ -130,6 +143,7 @@ def flat_config(self, fn: Callable[[ConfigSpecFragment], object]) -> helion.Conf
             "flatten_loops": self.flatten_loops._flat_config(self, fn),
             "l2_groupings": self.l2_groupings._flat_config(self, fn),
             "reduction_loops": self.reduction_loops._flat_config(self, fn),
+            "range_unroll_factors": self.range_unroll_factors._flat_config(self, fn),
             "num_warps": fn(NumWarpsFragment(1, 32, DEFAULT_NUM_WARPS)),
             "num_stages": fn(IntegerFragment(1, 8, DEFAULT_NUM_STAGES)),
             "indexing": fn(
@@ -151,7 +165,13 @@ def flat_config(self, fn: Callable[[ConfigSpecFragment], object]) -> helion.Conf
                 not config["flatten_loops"] or not config["flatten_loops"][0]
             ):
                 config["use_yz_grid"] = use_yz_grid
-        for name in ("loop_orders", "flatten_loops", "reduction_loops", "l2_groupings"):
+        for name in (
+            "loop_orders",
+            "flatten_loops",
+            "reduction_loops",
+            "l2_groupings",
+            "range_unroll_factors",
+        ):
             if not config[name]:
                 config.pop(name)
         return helion.Config(**config)  # pyre-ignore[6]
@@ -292,6 +312,20 @@ def _fill_missing(self) -> None:
         return None
 
 
+class RangeUnrollFactorSpec(_BlockIdItem):
+    def _fragment(self, base: ConfigSpec) -> IntegerFragment:
+        return IntegerFragment(0, 4, 0)
+
+    def _normalize(self, name: str, value: object) -> int:
+        if not isinstance(value, int):
+            raise InvalidConfig(f"{name} must be an integer, got {value!r}")
+        return value
+
+    def _fill_missing(self) -> int:
+        """Provide a value when not provided by the user."""
+        return 0
+
+
 def _product(seq: Sequence[int]) -> int:
     """Return the product of the elements in the sequence."""
     return functools.reduce(operator.mul, seq, 1)

helion/language/loops.py

@@ -26,6 +26,7 @@
 from ..autotuner.config_spec import FlattenLoopSpec
 from ..autotuner.config_spec import L2GroupingSpec
 from ..autotuner.config_spec import LoopOrderSpec
+from ..autotuner.config_spec import RangeUnrollFactorSpec
 from . import _decorators
 from helion.language.tile_proxy import Tile
 
@@ -230,17 +231,22 @@ def _add_config_choices(
     block_ids: list[int], *, is_tile: bool = False, has_begin: bool = False
 ) -> None:
     config_spec = CompileEnvironment.current().config_spec
+
     if len(block_ids) > 1:
         # Add loop reordering choice
         config_spec.loop_orders.append(LoopOrderSpec(block_ids))
         if is_tile and not has_begin:
             config_spec.flatten_loops.append(FlattenLoopSpec(block_ids))
 
-    if all(x._loop_type != LoopType.GRID for x in ExtendedAST.current()):  # is_grid
+    is_grid = all(x._loop_type != LoopType.GRID for x in ExtendedAST.current())
+    if is_grid:
         if len(block_ids) == 2:
             # TODO(jansel): support L2 grouping with 3+ dims (and maybe non-grids?)
             config_spec.l2_groupings.append(L2GroupingSpec(block_ids))
         config_spec.allow_use_yz_grid = _allow_use_yz_grid(config_spec, block_ids)
+    else:
+        for block_id in block_ids:
+            config_spec.range_unroll_factors.append(RangeUnrollFactorSpec([block_id]))
 
 
 def _allow_use_yz_grid(config_spec: ConfigSpec, block_ids: list[int]) -> bool:

helion/runtime/config.py

@@ -25,6 +25,7 @@ def __init__(
         flatten_loops: list[bool] | None = None,
         l2_groupings: list[int] | None = None,
         reduction_loops: list[int | None] | None = None,
+        range_unroll_factors: list[int] | None = None,
         num_warps: int | None = None,
         num_stages: int | None = None,
         use_yz_grid: bool | None = None,
@@ -40,6 +41,7 @@ def __init__(
             loop_orders: Permutes iteration order of tiles.
             l2_groupings: Reorders program IDs for L2 cache locality.
             reduction_loops: Configures reduction loop behavior.
+            range_unroll_factors: Loop unroll factors for tl.range calls.
             num_warps: Number of warps per block.
             num_stages: Number of stages for software pipelining.
             use_yz_grid: Whether to use yz grid dimensions.
@@ -53,6 +55,7 @@ def __init__(
             "flatten_loops": flatten_loops,
             "l2_groupings": l2_groupings,
             "reduction_loops": reduction_loops,
+            "range_unroll_factors": range_unroll_factors,
             "num_warps": num_warps,
             "num_stages": num_stages,
             "indexing": indexing,
@@ -138,6 +141,10 @@ def l2_groupings(self) -> list[int]:
     def use_yz_grid(self) -> bool:
         return cast("bool", self.config.get("use_yz_grid", False))
 
+    @property
+    def range_unroll_factors(self) -> list[int]:
+        return cast("list[int]", self.config.get("range_unroll_factors", []))
+
     @property
     def indexing(self) -> IndexingLiteral:
         return self.config.get("indexing", "pointer")  # type: ignore

test/test_autotuner.py

@@ -44,16 +44,16 @@ def test_config_fragment0(self):
         self.assertExpectedInline(
             "\n".join(map(repr, configs)),
             """\
-helion.Config(block_sizes=[16, 16, 16], loop_orders=[[0, 1]], l2_groupings=[1], num_warps=4, num_stages=3, indexing='pointer')
-helion.Config(block_sizes=[16, 32, 16], loop_orders=[[1, 0]], l2_groupings=[8], num_warps=32, num_stages=3, indexing='block_ptr')
-helion.Config(block_sizes=[32, 16, 16], loop_orders=[[1, 0]], l2_groupings=[32], num_warps=8, num_stages=8, indexing='block_ptr')
-helion.Config(block_sizes=[16, 16, 32], loop_orders=[[0, 1]], l2_groupings=[16], num_warps=4, num_stages=7, indexing='tensor_descriptor')
-helion.Config(block_sizes=[16, 16, 16], loop_orders=[[0, 1]], l2_groupings=[4], num_warps=8, num_stages=2, indexing='tensor_descriptor')
-helion.Config(block_sizes=[16, 16, 16], loop_orders=[[1, 0]], l2_groupings=[64], num_warps=4, num_stages=7, indexing='tensor_descriptor')
-helion.Config(block_sizes=[32, 128, 64], loop_orders=[[0, 1]], l2_groupings=[2], num_warps=16, num_stages=5, indexing='pointer')
-helion.Config(block_sizes=[16, 16, 16], loop_orders=[[1, 0]], l2_groupings=[2], num_warps=16, num_stages=3, indexing='tensor_descriptor')
-helion.Config(block_sizes=[16, 16, 16], loop_orders=[[0, 1]], l2_groupings=[16], num_warps=4, num_stages=2, indexing='block_ptr')
-helion.Config(block_sizes=[16, 16, 16], loop_orders=[[0, 1]], l2_groupings=[1], num_warps=1, num_stages=1, indexing='tensor_descriptor')""",
+helion.Config(block_sizes=[16, 16, 16], loop_orders=[[0, 1]], l2_groupings=[1], range_unroll_factors=[0], num_warps=4, num_stages=3, indexing='pointer')
+helion.Config(block_sizes=[16, 32, 16], loop_orders=[[1, 0]], l2_groupings=[8], range_unroll_factors=[1], num_warps=4, num_stages=4, indexing='tensor_descriptor')
+helion.Config(block_sizes=[16, 64, 128], loop_orders=[[0, 1]], l2_groupings=[8], range_unroll_factors=[2], num_warps=4, num_stages=4, indexing='pointer')
+helion.Config(block_sizes=[16, 16, 16], loop_orders=[[0, 1]], l2_groupings=[16], range_unroll_factors=[2], num_warps=8, num_stages=7, indexing='block_ptr')
+helion.Config(block_sizes=[16, 16, 16], loop_orders=[[0, 1]], l2_groupings=[8], range_unroll_factors=[0], num_warps=16, num_stages=1, indexing='pointer')
+helion.Config(block_sizes=[16, 16, 16], loop_orders=[[1, 0]], l2_groupings=[64], range_unroll_factors=[2], num_warps=32, num_stages=7, indexing='tensor_descriptor')
+helion.Config(block_sizes=[32, 128, 64], loop_orders=[[0, 1]], l2_groupings=[2], range_unroll_factors=[4], num_warps=4, num_stages=4, indexing='tensor_descriptor')
+helion.Config(block_sizes=[256, 32, 128], loop_orders=[[1, 0]], l2_groupings=[16], range_unroll_factors=[1], num_warps=32, num_stages=2, indexing='block_ptr')
+helion.Config(block_sizes=[32, 16, 16], loop_orders=[[0, 1]], l2_groupings=[1], range_unroll_factors=[3], num_warps=1, num_stages=8, indexing='tensor_descriptor')
+helion.Config(block_sizes=[16, 32, 16], loop_orders=[[0, 1]], l2_groupings=[32], range_unroll_factors=[2], num_warps=4, num_stages=5, indexing='block_ptr')""",
         )
 
     @patch.object(_compat, "_supports_tensor_descriptor", lambda: True)