Limit tensor block numel to triton's requirements

Fixes #456

Author: oulgen

helion/autotuner/block_id_sequence.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import dataclasses
+import math
 from typing import TYPE_CHECKING
 from typing import Callable
 from typing import MutableSequence
@@ -185,6 +186,10 @@ def _normalize(
                     f"(one for each tiled dimension), got {len(values)}. "
                     f"Did you forget to specify block sizes for all your hl.tile() dimensions?"
                 ) from None
+        if name == "block_sizes" and math.prod(values) > 1048576:
+            raise InvalidConfig(
+                "Triton does not allow for tensor numel greater than 1048576"
+            )
         for i, spec in enumerate(self._data):
             values[i] = spec._normalize(f"config[{name}][{i}]", values[i])
         return values

test/test_errors.py

@@ -60,6 +60,25 @@ def fn(x: torch.Tensor) -> torch.Tensor:
                 (torch.randn(4, 8, 16, device=DEVICE),),
             )
 
+    def test_invalid_tensor_numel(self):
+        """Test that InvalidConfig shows helpful message for invalid block sizes."""
+
+        @helion.kernel(config=helion.Config(block_sizes=[2048, 1024]))
+        def fn(x: torch.Tensor) -> torch.Tensor:
+            out = torch.zeros_like(x)
+            for tile_m, tile_n in hl.tile(x.size()):
+                out[tile_m, tile_n] = x[tile_m, tile_n]
+            return out
+
+        with self.assertRaisesRegex(
+            helion.exc.InvalidConfig,
+            "Triton does not allow for tensor numel greater than 1048576",
+        ):
+            code_and_output(
+                fn,
+                (torch.randn(2048, 2048, device=DEVICE),),
+            )
+
     def test_rank_mismatch_indexing(self):
         """Test that RankMismatch shows tensor shapes in indexing errors."""