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| 1 | +# Copyright 2025 Arm Limited and/or its affiliates. |
| 2 | +# |
| 3 | +# This source code is licensed under the BSD-style license found in the |
| 4 | +# LICENSE file in the root directory of this source tree. |
| 5 | + |
| 6 | +# pyre-unsafe |
| 7 | + |
| 8 | +import operator |
| 9 | + |
| 10 | +from executorch.backends.arm._passes import ArmPass |
| 11 | +from executorch.exir.dialects._ops import ops as exir_ops |
| 12 | + |
| 13 | +# We'll decompose only the EXIR edge max_pool2d ops when dilation > 1 |
| 14 | +EDGE_MAXPOOL2D = ( |
| 15 | + exir_ops.edge.aten.max_pool2d.default, |
| 16 | + exir_ops.edge.aten.max_pool2d_with_indices.default, |
| 17 | +) |
| 18 | + |
| 19 | + |
| 20 | +class DecomposeMaxPool2DPass(ArmPass): |
| 21 | + """ |
| 22 | + Decompose dilated max_pool2d (EXIR edge ops) into space-to-batch -> maxpool -> batch-to-space. |
| 23 | + """ |
| 24 | + |
| 25 | + def call_operator(self, op, args, kwargs, meta): |
| 26 | + # Only intercept EXIR edge max_pool2d ops |
| 27 | + if op not in EDGE_MAXPOOL2D: |
| 28 | + return super().call_operator(op, args, kwargs, meta) |
| 29 | + |
| 30 | + # detect whether indices variant |
| 31 | + is_with_indices = op is exir_ops.edge.aten.max_pool2d_with_indices.default |
| 32 | + |
| 33 | + # Normalize missing trailing args to their defaults |
| 34 | + x = args[0] |
| 35 | + kernel_size = args[1] |
| 36 | + stride = args[2] |
| 37 | + padding = args[3] if len(args) >= 4 else 0 |
| 38 | + dilation = args[4] if len(args) >= 5 else 1 |
| 39 | + |
| 40 | + # Normalize attributes |
| 41 | + pad_h, pad_w = (padding, padding) if isinstance(padding, int) else padding |
| 42 | + d_h, d_w = (dilation, dilation) if isinstance(dilation, int) else dilation |
| 43 | + k_h, k_w = ( |
| 44 | + (kernel_size, kernel_size) if isinstance(kernel_size, int) else kernel_size |
| 45 | + ) |
| 46 | + s_h, s_w = (stride, stride) if isinstance(stride, int) else stride |
| 47 | + |
| 48 | + # If no dilation: call EXIR edge op with only supported args (x, kernel, stride[, padding]) |
| 49 | + if d_h == 1 and d_w == 1: |
| 50 | + minimal_args = [x, kernel_size, stride] |
| 51 | + # only include padding if non-zero |
| 52 | + if (pad_h, pad_w) != (0, 0): |
| 53 | + minimal_args.append((pad_h, pad_w)) |
| 54 | + return super().call_operator(op, tuple(minimal_args), {}, meta) |
| 55 | + |
| 56 | + # Compute padded and packed dimensions for dilation > 1 |
| 57 | + N, C, H, W = x.data.size() |
| 58 | + ph, pw = pad_h, pad_w |
| 59 | + ph2, pw2 = pad_h, pad_w |
| 60 | + H_pad = H + ph + ph2 |
| 61 | + W_pad = W + pw + pw2 |
| 62 | + H_pack = (H_pad + d_h - 1) // d_h |
| 63 | + W_pack = (W_pad + d_w - 1) // d_w |
| 64 | + extra_h = 0 if H_pack < k_h else (s_h - ((H_pack - k_h) % s_h)) % s_h |
| 65 | + extra_w = 0 if W_pack < k_w else (s_w - ((W_pack - k_w) % s_w)) % s_w |
| 66 | + ph2 += extra_h * d_h |
| 67 | + pw2 += extra_w * d_w |
| 68 | + |
| 69 | + # 1) Pad via EXIR edge pad (preserves dtype) |
| 70 | + pad_edge = exir_ops.edge.aten.constant_pad_nd.default |
| 71 | + pads = [pw, pw2, ph, ph2, 0, 0, 0, 0] |
| 72 | + x_pad = super().call_operator( |
| 73 | + pad_edge, |
| 74 | + (x, pads, 0), |
| 75 | + {}, |
| 76 | + meta, |
| 77 | + ) |
| 78 | + |
| 79 | + # 2) Space-to-batch: reshape and permute |
| 80 | + x2 = super().call_operator( |
| 81 | + exir_ops.edge.aten.view_copy.default, |
| 82 | + (x_pad, [N, C, H_pack, d_h, W_pack, d_w]), |
| 83 | + {}, |
| 84 | + meta, |
| 85 | + ) |
| 86 | + x2 = super().call_operator( |
| 87 | + exir_ops.edge.aten.permute_copy.default, |
| 88 | + (x2, [3, 5, 0, 1, 2, 4]), |
| 89 | + {}, |
| 90 | + meta, |
| 91 | + ) |
| 92 | + x2 = super().call_operator( |
| 93 | + exir_ops.edge.aten.view_copy.default, |
| 94 | + (x2, [N * d_h * d_w, C, H_pack, W_pack]), |
| 95 | + {}, |
| 96 | + meta, |
| 97 | + ) |
| 98 | + |
| 99 | + # 3) Core pooling on packed tensor |
| 100 | + pool_edge_op = ( |
| 101 | + exir_ops.edge.aten.max_pool2d_with_indices.default |
| 102 | + if is_with_indices |
| 103 | + else exir_ops.edge.aten.max_pool2d.default |
| 104 | + ) |
| 105 | + pool_args = (x2, (k_h, k_w), (s_h, s_w), (0, 0)) |
| 106 | + pool_out = super().call_operator( |
| 107 | + pool_edge_op, |
| 108 | + pool_args, |
| 109 | + {}, |
| 110 | + meta, |
| 111 | + ) |
| 112 | + |
| 113 | + # Unpack pooled result |
| 114 | + if is_with_indices: |
| 115 | + pooled_proxy = super().call_operator( |
| 116 | + operator.getitem, |
| 117 | + (pool_out, 0), |
| 118 | + {}, |
| 119 | + meta, |
| 120 | + ) |
| 121 | + indices_proxy = super().call_operator( |
| 122 | + operator.getitem, |
| 123 | + (pool_out, 1), |
| 124 | + {}, |
| 125 | + meta, |
| 126 | + ) |
| 127 | + pooled_fake, _ = pool_out.data |
| 128 | + else: |
| 129 | + pooled_proxy = pool_out |
| 130 | + pooled_fake = pool_out.data |
| 131 | + indices_proxy = None |
| 132 | + |
| 133 | + _, C_out, H_out, W_out = pooled_fake.shape |
| 134 | + |
| 135 | + # 4) Batch-to-space: reshape and permute back |
| 136 | + out = super().call_operator( |
| 137 | + exir_ops.edge.aten.view_copy.default, |
| 138 | + (pooled_proxy, [d_h, d_w, N, C_out, H_out, W_out]), |
| 139 | + {}, |
| 140 | + meta, |
| 141 | + ) |
| 142 | + out = super().call_operator( |
| 143 | + exir_ops.edge.aten.permute_copy.default, |
| 144 | + (out, [2, 3, 4, 0, 5, 1]), |
| 145 | + {}, |
| 146 | + meta, |
| 147 | + ) |
| 148 | + # now flatten back into (N, C, H_out*d_h, W_out*d_w) |
| 149 | + out = super().call_operator( |
| 150 | + exir_ops.edge.aten.view_copy.default, |
| 151 | + (out, [N, C_out, H_out * d_h, W_out * d_w]), |
| 152 | + {}, |
| 153 | + meta, |
| 154 | + ) |
| 155 | + |
| 156 | + # 5) Final crop |
| 157 | + S_top = ph // d_h + (1 if ph % d_h else 0) |
| 158 | + S_left = pw // d_w + (1 if pw % d_w else 0) |
| 159 | + S_top = max(0, min(S_top, H_out * d_h - H)) |
| 160 | + S_left = max(0, min(S_left, W_out * d_w - W)) |
| 161 | + out = super().call_operator( |
| 162 | + exir_ops.edge.aten.slice_copy.Tensor, |
| 163 | + (out, 2, S_top, S_top + H), |
| 164 | + {}, |
| 165 | + meta, |
| 166 | + ) |
| 167 | + out = super().call_operator( |
| 168 | + exir_ops.edge.aten.slice_copy.Tensor, |
| 169 | + (out, 3, S_left, S_left + W), |
| 170 | + {}, |
| 171 | + meta, |
| 172 | + ) |
| 173 | + |
| 174 | + if is_with_indices: |
| 175 | + # Reconstruct indices |
| 176 | + idx = super().call_operator( |
| 177 | + exir_ops.edge.aten.view_copy.default, |
| 178 | + (indices_proxy, [d_h, d_w, N, C_out, H_out, W_out]), |
| 179 | + {}, |
| 180 | + meta, |
| 181 | + ) |
| 182 | + idx = super().call_operator( |
| 183 | + exir_ops.edge.aten.permute_copy.default, |
| 184 | + (idx, [2, 3, 4, 0, 5, 1]), |
| 185 | + {}, |
| 186 | + meta, |
| 187 | + ) |
| 188 | + idx = super().call_operator( |
| 189 | + exir_ops.edge.aten.view_copy.default, |
| 190 | + (idx, [N, C_out, H_out * d_h, W_out * d_w]), |
| 191 | + {}, |
| 192 | + meta, |
| 193 | + ) |
| 194 | + idx = super().call_operator( |
| 195 | + exir_ops.edge.aten.slice_copy.Tensor, |
| 196 | + (idx, 2, S_top, S_top + H), |
| 197 | + {}, |
| 198 | + meta, |
| 199 | + ) |
| 200 | + idx = super().call_operator( |
| 201 | + exir_ops.edge.aten.slice_copy.Tensor, |
| 202 | + (idx, 3, S_left, S_left + W), |
| 203 | + {}, |
| 204 | + meta, |
| 205 | + ) |
| 206 | + return out, idx |
| 207 | + |
| 208 | + return out |
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