Revert "Reland D62220158 (#136213)"

This reverts commit 083c9149b7.

Reverted https://github.com/pytorch/pytorch/pull/136213 on behalf of https://github.com/jeanschmidt due to Seems to have introduced regressions in rocm signals ([comment](https://github.com/pytorch/pytorch/pull/136213#issuecomment-2360885064))

test/inductor/test_pad_mm.py

@@ -9,7 +9,6 @@ from torch._inductor.fx_passes.pad_mm import (
     get_pad_cache,
     get_padded_length,
     should_pad_common,
-    should_pad_mm_bf16,
 )
 from torch._inductor.test_case import run_tests, TestCase
 from torch._inductor.utils import fresh_inductor_cache, is_big_gpu, run_and_get_code
@@ -450,40 +449,6 @@ class PadMMTest(TestCase):
             repr(get_pad_cache().get_local_cache())
         )
 
-    @fresh_inductor_cache()
-    @inductor_config.patch(
-        post_grad_fusion_options={"pad_aten_mm_pass": {"k_threshold_to_pad": 8388608}}
-    )
-    def test_pad_mm_bf16(self):
-        m = 2
-        n = 13
-        k = 15691904
-        mat1 = torch.ones((m, k), device="cuda", dtype=torch.bfloat16)
-        mat2 = torch.ones((k, n), device="cuda", dtype=torch.bfloat16)
-        expected_alignment = get_alignment_size(mat1)
-
-        assert expected_alignment == 8, "Alignment for bfloat16 should be 8"
-        assert should_pad_common(
-            mat1, mat2
-        ), "This should pass the common padding criteria"
-        if torch.cuda.get_device_capability() < (9, 0):
-            assert should_pad_mm_bf16(
-                mat1.dtype, m, n, k
-            ), "This should pass the should_pad_mm_bf16 padding criteria"
-
-        @torch.compile()
-        def mm(mat1, mat2):
-            return torch.mm(mat1, mat2)
-
-        res2, (code,) = run_and_get_code(mm, mat1, mat2)
-        mm_expected_result = torch.mm(mat1, mat2)
-        # in call code, expect to see a single pad per input, and then we should see padded allocation for output
-        FileCheck().check("del async_compile").check_count(
-            ".run(", 2, exactly=True
-        ).check("empty_strided_cuda((8, 16)").run(code)
-
-        assert torch.allclose(res2, mm_expected_result), "MM results are not identical"
-
 
 if __name__ == "__main__":
     if HAS_CUDA:

torch/_inductor/fx_passes/pad_mm.py

@@ -364,23 +364,6 @@ def should_pad(key: str, ori_time, pad_time) -> bool:
     return should_pad
 
 
-def should_pad_mm_bf16(dtype, M, N, K):
-    # always force pad for mm with bf16 when the following are satisfied to avoid perf regression
-    large_k_threshold_to_pad = torch._inductor.config.post_grad_fusion_options[
-        "pad_aten_mm_pass"
-    ].get("k_threshold_to_pad", 8388608)
-    if (
-        dtype is torch.bfloat16
-        and K > M
-        and K > N
-        and N % 2 == 1
-        and K >= large_k_threshold_to_pad
-        and torch.cuda.get_device_capability() < (9, 0)
-    ):  # doesnt repro on h100s:
-        return True
-    return False
-
-
 def should_pad_bench(
     match, mat1: Tensor, mat2: Tensor, op, input: Optional[Tensor] = None
 ) -> bool:
@@ -427,12 +410,6 @@ def should_pad_bench(
         if torch._inductor.config.force_shape_pad:
             return True
 
-        if (
-            "pad_aten_mm_pass" in torch._inductor.config.post_grad_fusion_options
-            and should_pad_mm_bf16(mat1.dtype, m, n, k)
-        ):
-            return True
-
         if not has_triton():
             return False
 

torch/_inductor/fx_passes/split_cat.py

@@ -65,7 +65,6 @@ post_grad_pass_names = [
     "decompose_mm_pass",
     "unbind_stack_aten_pass",
     "shape_padding_multiplier",
-    "pad_aten_mm_pass",
 ]
 
 for pass_name in pre_grad_pass_names: