Add the gather op. (#219)

* Start adding gather.

* Gather cpu implementation + use in simple training.

* Add scatter_add for the gradient of gather.

* Simple cpu implementation of scatter_add.

* Use gather in the simple-training backprop.

1 files changed, 14 insertions, 0 deletions

diff --git a/candle-core/src/cuda_backend.rs b/candle-core/src/cuda_backend.rs
index a5633836..43bfef2d 100644
--- a/candle-core/src/cuda_backend.rs
+++ b/candle-core/src/cuda_backend.rs
@@ -1064,6 +1064,20 @@ impl BackendStorage for CudaStorage {
     fn index_select(&self, _: &Self, _: &Layout, _: &Layout, _: usize) -> Result<Self> {
         Err(CudaError::InternalError("TODO: implement index-select").into())
     }
+    fn gather(&self, _: &Layout, _: &Self, _: &Layout, _: usize) -> Result<Self> {
+        Err(CudaError::InternalError("TODO: implement gather").into())
+    }
+    fn scatter_add(
+        &self,
+        _: &Layout,
+        _: &Self,
+        _: &Layout,
+        _: &Self,
+        _: &Layout,
+        _: usize,
+    ) -> Result<Self> {
+        Err(CudaError::InternalError("TODO: implement scatter-add").into())
+    }
     fn index_add(
         &self,
         _: &Layout,