TaoLv commented on a change in pull request #17091: broadcast_axis optimization
URL: https://github.com/apache/incubator-mxnet/pull/17091#discussion_r361564897
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File path: src/operator/tensor/broadcast_reduce_op_value.cc
##########
@@ -32,6 +32,41 @@ DMLC_REGISTER_PARAMETER(BroadcastAxesParam);
DMLC_REGISTER_PARAMETER(BroadcastToParam);
DMLC_REGISTER_PARAMETER(BroadcastLikeParam);
+template<typename DType>
+void BroadcastAxisKer(DType* src,
+ DType* dst,
+ index_t outer,
+ index_t inner,
+ index_t size) {
+#pragma omp parallel for
num_threads(engine::OpenMP::Get()->GetRecommendedOMPThreadCount())
+ for (index_t i = 0; i < outer * size; i++) {
+ const index_t m = i / size;
+ const index_t n = i % size;
+ void* offset = reinterpret_cast<void*>(dst + m * size * inner + n * inner);
+ memcpy(offset, reinterpret_cast<void*>(src + m * inner), inner * sizeof
(DType));
+ }
+}
+
+inline void BroadcastAxisComputeCPU(const nnvm::NodeAttrs& attrs,
+ const OpContext& ctx,
+ const std::vector<TBlob>& inputs,
+ const std::vector<OpReqType>& req,
+ const std::vector<TBlob>& outputs) {
+ using namespace mshadow;
+ const BroadcastAxesParam& param =
nnvm::get<BroadcastAxesParam>(attrs.parsed);
+ if (param.axis.ndim() == 1 && inputs[0].shape_[param.axis[0]] == 1 && req[0]
== kWriteTo) {
Review comment:
It seems broadcast_axis doesn't support negative axis even before this
change. See
https://github.com/apache/incubator-mxnet/blob/master/src/operator/tensor/broadcast_reduce_op.h#L386.
```python
import mxnet as mx
a = mx.random.uniform(shape=(4, 5, 1))
b = mx.nd.broadcast_axis(a, axis=-1, size=6)
print(b)
```
Will cause error:
```bash
Traceback (most recent call last):
File "test_bcast.py", line 4, in <module>
b = mx.nd.broadcast_axis(a, axis=-1, size=6)
File "<string>", line 60, in broadcast_axis
File
"/home/lvtao/miniconda3/envs/mxnet/lib/python3.6/site-packages/mxnet/_ctypes/ndarray.py",
line 107, in _imperative_invoke
ctypes.byref(out_stypes)))
File
"/home/lvtao/miniconda3/envs/mxnet/lib/python3.6/site-packages/mxnet/base.py",
line 278, in check_call
raise MXNetError(py_str(_LIB.MXGetLastError()))
mxnet.base.MXNetError: [18:53:34] include/mxnet/./tuple.h:206: Check failed:
i >= 0 && i < ndim(): index = -1 must be in range [0, 3)
```
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