[Fix,TOPI] Consolidate generic and x86 scatter nd

The generic scatter nd was almost identical to the x86 one and was not
tested. They now are one and the same.

python/tvm/relay/op/strategy/x86.py

@@ -772,7 +772,7 @@ def scatter_nd_strategy_cpu(attrs, inputs, out_type, target):
     """scatter_nd x86 strategy"""
     strategy = _op.OpStrategy()
     strategy.add_implementation(
-        wrap_compute_scatter_nd(topi.x86.scatter_nd),
+        wrap_compute_scatter_nd(topi.scatter_nd),
         wrap_topi_schedule(topi.generic.schedule_extern),
         name="scatter_nd.x86",
         plevel=10,

python/tvm/topi/scatter.py

@@ -268,63 +268,58 @@ def scatter_nd(data, indices, updates, mode):
     _verify_scatter_nd_inputs(data, indices, updates)
 
     def gen_ir(data_ptr, indices_ptr, updates_ptr, out_ptr):
+        # pylint: disable=invalid-name
         ib = ir_builder.create()
 
         data = ib.buffer_ptr(data_ptr)
         indices = ib.buffer_ptr(indices_ptr)
         updates = ib.buffer_ptr(updates_ptr)
         out = ib.buffer_ptr(out_ptr)
 
-        fused_shape = 1
-        for i in data.shape:
-            fused_shape *= i
-        with ib.for_range(0, fused_shape) as i:
-            out[i] = data[i]
-
         # We combine all the indices dimensions but the first one into a single
         # dimension so we can iterate it in single loop instead of an arbitrary
-        # number of loops. We do the same thing for all the data dimensions.
+        # number of loops. We do the same thing for all the update dimensions.
         fused_indices_dimension = 1
         for i in indices_ptr.shape[1:]:
             fused_indices_dimension *= i
 
-        fused_data_dimension = 1
-        for i in data_ptr.shape[len(indices_ptr.shape) - 1 :]:
-            fused_data_dimension *= i
+        fused_updates_dimension = 1
+        for i in updates_ptr.shape[len(indices_ptr.shape) - 1 :]:
+            fused_updates_dimension *= i
+
+        fused_shape = 1
+        for i in data_ptr.shape:
+            fused_shape *= i
+
+        with ib.for_range(0, fused_shape) as i:
+            out[i] = data[i]
 
-        with ib.for_range(0, fused_indices_dimension, name="i") as i:
-            with ib.for_range(0, fused_data_dimension, name="j") as j:
-                offset = fused_data_dimension
+        with ib.for_range(0, fused_indices_dimension) as i:
+            with ib.for_range(0, fused_updates_dimension, kind="parallel") as j:
+                offset = fused_updates_dimension
                 index = j  # This is x_M, .. x_{N-1} part of the index into out.
                 # Build up the indices[0, y_0, .. y_{K-1}], .. indices[M-1, y_0, .. y_{K-1}] part
                 # of the index into out.
                 for l in reversed(range(indices_ptr.shape[0].value)):
                     # indices[i * l * fused_indices_dimension] = indices[l, y_0, ... y_{k-1}]
                     index += offset * indices[i + l * fused_indices_dimension]
-                    ib.emit(
-                        AssertStmt(
-                            indices[i + l * fused_indices_dimension] < shape[l],
-                            StringImm("index out of bounds"),
-                            Evaluate(0),
-                        )
-                    )
-                    offset *= shape[l]
-                if mode == "add":
-                    out[index] += updates[i * fused_data_dimension + j]
-                elif mode == "update":
-                    out[index] = updates[i * fused_data_dimension + j]
+                    offset *= data_ptr.shape[l]
+                if mode == "update":
+                    out[index] = updates[i * fused_updates_dimension + j]
+                elif mode == "add":
+                    out[index] += updates[i * fused_updates_dimension + j]
                 else:
                     raise NotImplementedError("scatter_nd mode not in [update, add]:", mode)
 
         return ib.get()
 
-    out_buf = decl_buffer(shape, data.dtype, "out_buf")
+    out_buf = decl_buffer(data.shape, data.dtype, "out_buf")
     return extern(
-        [shape],
+        [data.shape],
         [data, indices, updates],
         lambda ins, outs: gen_ir(ins[0], ins[1], ins[2], outs[0]),
         dtype=data.dtype,
         out_buffers=[out_buf],
-        name="scatter_nd_generic",
-        tag="scatter_nd_generic",
+        name="scatter_nd.generic",
+        tag="scatter_nd.generic",
     )

python/tvm/topi/x86/__init__.py

@@ -40,7 +40,6 @@
 from .sparse import *
 from .conv2d_alter_op import *
 from .dense_alter_op import *
-from .scatter import *
 from .group_conv2d import *
 from .math_alter_op import *
 from .concat import *

tests/python/topi/python/test_topi_scatter.py

@@ -33,10 +33,6 @@ def check_scatter_nd(data, indices, updates, out, mode="add"):
                 lambda x, y, z: topi.cuda.scatter_nd(x, y, z, mode),
                 topi.generic.schedule_extern,
             ),
-            "cpu": (
-                lambda x, y, z: topi.x86.scatter_nd(x, y, z, mode),
-                topi.generic.schedule_extern,
-            ),
         }
         fcompute, fschedule = tvm.topi.testing.dispatch(target, implementations)
         tvm.topi.testing.compare_numpy_tvm(