`mps`: Alternative implementation for `repeat_interleave` (#766)

* mps: alt. implementation for repeat_interleave

* style

* Bump mps version of PyTorch in the documentation.

* Apply suggestions from code review
Co-authored-by: Suraj Patil <surajp815@gmail.com>

* Simplify: do not check for device.

* style

* Fix repeat dimensions:

- The unconditional embeddings are always created from a single prompt.
- I was shadowing the batch_size var.

* Split long lines as suggested by Suraj.
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
Co-authored-by: Suraj Patil <surajp815@gmail.com>

docs/source/optimization/mps.mdx

@@ -19,7 +19,7 @@ specific language governing permissions and limitations under the License.
 - Mac computer with Apple silicon (M1/M2) hardware.
 - macOS 12.3 or later.
 - arm64 version of Python.
-- PyTorch [Preview (Nightly)](https://pytorch.org/get-started/locally/), version `1.13.0.dev20220830` or later.
+- PyTorch [Preview (Nightly)](https://pytorch.org/get-started/locally/), version `1.14.0.dev20221007` or later.
 
 ## Inference Pipeline
 

src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion.py

@@ -218,8 +218,10 @@ class StableDiffusionPipeline(DiffusionPipeline):
             text_input_ids = text_input_ids[:, : self.tokenizer.model_max_length]
         text_embeddings = self.text_encoder(text_input_ids.to(self.device))[0]
 
-        # duplicate text embeddings for each generation per prompt
-        text_embeddings = text_embeddings.repeat_interleave(num_images_per_prompt, dim=0)
+        # duplicate text embeddings for each generation per prompt, using mps friendly method
+        bs_embed, seq_len, _ = text_embeddings.shape
+        text_embeddings = text_embeddings.repeat(1, num_images_per_prompt, 1)
+        text_embeddings = text_embeddings.view(bs_embed * num_images_per_prompt, seq_len, -1)
 
         # here `guidance_scale` is defined analog to the guidance weight `w` of equation (2)
         # of the Imagen paper: https://arxiv.org/pdf/2205.11487.pdf . `guidance_scale = 1`
@@ -256,8 +258,10 @@ class StableDiffusionPipeline(DiffusionPipeline):
             )
             uncond_embeddings = self.text_encoder(uncond_input.input_ids.to(self.device))[0]
 
-            # duplicate unconditional embeddings for each generation per prompt
-            uncond_embeddings = uncond_embeddings.repeat_interleave(batch_size * num_images_per_prompt, dim=0)
+            # duplicate unconditional embeddings for each generation per prompt, using mps friendly method
+            seq_len = uncond_embeddings.shape[1]
+            uncond_embeddings = uncond_embeddings.repeat(batch_size, num_images_per_prompt, 1)
+            uncond_embeddings = uncond_embeddings.view(batch_size * num_images_per_prompt, seq_len, -1)
 
             # For classifier free guidance, we need to do two forward passes.
             # Here we concatenate the unconditional and text embeddings into a single batch