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[PHI] Unify expand_grad kernel behavior between cpu and gpu #74123

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merged 1 commit into from
Jul 21, 2025
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[PHI] Unify expand_grad kernel behavior between cpu and gpu #74123

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14 changes: 6 additions & 8 deletions paddle/phi/kernels/impl/expand_grad_kernel_impl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -85,8 +85,10 @@ void ExpandGradKernel(const Context& dev_ctx,
const DenseTensor& out_grad,
const IntArray& shape,
DenseTensor* in_grad) {
auto expand_shape = shape.GetData();
auto x_dims = x.dims();
auto out_grad_dims = out_grad.dims();
std::vector<int64_t> expand_shape = phi::vectorize<int64_t>(out_grad_dims);

if (x.numel() == 0 || out_grad.numel() == 0 ||
(in_grad && in_grad->numel() == 0)) {
dev_ctx.template Alloc<T>(in_grad);
Expand All @@ -99,11 +101,11 @@ void ExpandGradKernel(const Context& dev_ctx,
return;
}

if (in_grad->dims() == out_grad.dims()) {
if (in_grad->dims() == out_grad_dims) {
phi::Copy(dev_ctx, out_grad, dev_ctx.GetPlace(), false, in_grad);
return;
}
auto vec_in_dims = common::vectorize<int>(x_dims);
auto vec_in_dims = common::vectorize<int64_t>(x_dims);
auto diff = expand_shape.size() - vec_in_dims.size();
vec_in_dims.insert(vec_in_dims.begin(), diff, 1);
// 1. reshape_dims_vec is the broadcast parameter.
Expand All @@ -112,11 +114,7 @@ void ExpandGradKernel(const Context& dev_ctx,
// size.
std::vector<int> repeat_times(vec_in_dims.size());
for (size_t i = 0; i < vec_in_dims.size(); ++i) {
if (expand_shape[i] < 0) {
repeat_times[i] = 1;
} else {
repeat_times[i] = expand_shape[i] / vec_in_dims[i];
}
repeat_times[i] = expand_shape[i] / vec_in_dims[i];
}
std::vector<int> reshape_dims_vec;
std::vector<int> reduce_dims_vec;
Expand Down