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Fix slice data size (#1394)

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* fix slice data size and add tests

* fix contiguous flag

* simplify stride and perform copy for non-contiguous arrays

* fix cpu

* comment
This commit is contained in:
Awni Hannun
2024-09-04 19:10:43 -07:00
committed by GitHub
parent 11371fe251
commit 7cca1727af
12 changed files with 129 additions and 39 deletions
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10
mlx/backend/common/primitives.cpp
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@@ -505,8 +505,16 @@ void Slice::eval(const std::vector<array>& inputs, array& out) {
/* int64_t o_offset = */ 0,
/* CopyType ctype = */ CopyType::General);
} else {
size_t data_end = 1;
for (int i = 0; i < end_indices_.size(); ++i) {
if (in.shape()[i] > 1) {
auto end_idx = start_indices_[i] + out.shape()[i] * strides_[i] - 1;
data_end += end_idx * in.strides()[i];
}
}
size_t data_size = data_end - data_offset;
std::vector<size_t> ostrides{inp_strides.begin(), inp_strides.end()};
shared_buffer_slice(in, ostrides, data_offset, out);
shared_buffer_slice(in, ostrides, data_offset, data_size, out);
}
}

22
mlx/backend/common/slicing.cpp
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@@ -6,18 +6,16 @@ namespace mlx::core {
std::tuple<bool, int64_t, std::vector<int64_t>> prepare_slice(
const array& in,
std::vector<int>& start_indices,
std::vector<int>& strides) {
const std::vector<int>& start_indices,
const std::vector<int>& strides) {
int64_t data_offset = 0;
bool copy_needed = false;
std::vector<int64_t> inp_strides(in.ndim(), 0);
for (int i = 0; i < in.ndim(); ++i) {
data_offset += start_indices[i] * in.strides()[i];
inp_strides[i] = in.strides()[i] * strides[i];
copy_needed |= strides[i] < 0;
}
return std::make_tuple(copy_needed, data_offset, inp_strides);
}
@@ -25,26 +23,16 @@ void shared_buffer_slice(
const array& in,
const std::vector<size_t>& out_strides,
size_t data_offset,
size_t data_size,
array& out) {
// Compute row/col contiguity
auto [data_size, is_row_contiguous, is_col_contiguous] =
auto [no_bsx_size, is_row_contiguous, is_col_contiguous] =
check_contiguity(out.shape(), out_strides);
auto flags = in.flags();
flags.row_contiguous = is_row_contiguous;
flags.col_contiguous = is_col_contiguous;
if (data_size == 1) {
// Broadcasted scalar array is contiguous.
flags.contiguous = true;
} else if (data_size == in.data_size()) {
// Means we sliced a broadcasted dimension so leave the "no holes" flag
// alone.
} else {
// We sliced something. So either we are row or col contiguous or we
// punched a hole.
flags.contiguous &= flags.row_contiguous || flags.col_contiguous;
}
flags.contiguous = (no_bsx_size == data_size);
out.copy_shared_buffer(in, out_strides, flags, data_size, data_offset);
}

5
mlx/backend/common/slicing.h
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@@ -8,13 +8,14 @@ namespace mlx::core {
std::tuple<bool, int64_t, std::vector<int64_t>> prepare_slice(
const array& in,
std::vector<int>& start_indices,
std::vector<int>& strides);
const std::vector<int>& start_indices,
const std::vector<int>& strides);
void shared_buffer_slice(
const array& in,
const std::vector<size_t>& out_strides,
size_t data_offset,
size_t data_size,
array& out);
} // namespace mlx::core

7
mlx/backend/common/utils.h
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@@ -135,7 +135,7 @@ template <typename stride_t>
inline auto check_contiguity(
const std::vector<int>& shape,
const std::vector<stride_t>& strides) {
size_t data_size = 1;
size_t no_broadcast_data_size = 1;
size_t f_stride = 1;
size_t b_stride = 1;
bool is_row_contiguous = true;
@@ -147,11 +147,12 @@ inline auto check_contiguity(
f_stride *= shape[i];
b_stride *= shape[ri];
if (strides[i] > 0) {
data_size *= shape[i];
no_broadcast_data_size *= shape[i];
}
}
return std::make_tuple(data_size, is_row_contiguous, is_col_contiguous);
return std::make_tuple(
no_broadcast_data_size, is_row_contiguous, is_col_contiguous);
}
} // namespace mlx::core