Fix an issue when fusing BatchNorm in backprop #48893
Merged
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Previous PR #48063 might hit CUDNN_STATUS_NOT_SUPPORTED error if the Add node has both inputs to be the BatchNorm nodes, in which case we will mistakenly mark both BatchNormGrad as valid for fusion. Though it is not possible that both BatchNormGrad in the backward pass will be fused, there is chance that the forward pass and backward pass select different branch to fuse, causing the unexpected reserve space sizes.
This PR fixes this issue by checking if the BatchNormGrad's directly connected forward BatchNorm matches the to-be-fused forward BatchNorm. In addition, the unit tests are updated to test the double BN inputs of add op.
cc. @nluehr