Fixes for the stable diffusion example. (#342)

* Fixes for the stable diffusion example.

* Bugfix.

* Another fix.

* Fix for group-norm.

* More fixes to get SD to work.

candle-examples/examples/stable-diffusion/clip.rs

@@ -29,7 +29,7 @@ pub struct Config {
     embed_dim: usize,       // aka config.hidden_size
     activation: Activation, // aka config.hidden_act
     intermediate_size: usize,
-    max_position_embeddings: usize,
+    pub max_position_embeddings: usize,
     // The character to use for padding, use EOS when not set.
     pad_with: Option<String>,
     num_hidden_layers: usize,
@@ -90,7 +90,7 @@ impl ClipTextEmbeddings {
             vs.pp("position_embedding"),
         )?;
         let position_ids =
-            Tensor::arange(0u32, c.max_position_embeddings as u32, vs.device())?.unsqueeze(1)?;
+            Tensor::arange(0u32, c.max_position_embeddings as u32, vs.device())?.unsqueeze(0)?;
         Ok(ClipTextEmbeddings {
             token_embedding,
             position_embedding,

candle-examples/examples/stable-diffusion/embeddings.rs

@@ -49,7 +49,7 @@ impl Timesteps {
         let exponent = (exponent / (half_dim as f64 - self.downscale_freq_shift))?;
         let emb = exponent.exp()?;
         // emb = timesteps[:, None].float() * emb[None, :]
-        let emb = (xs.unsqueeze(D::Minus1)? * emb.unsqueeze(0)?)?;
+        let emb = xs.unsqueeze(D::Minus1)?.broadcast_mul(&emb.unsqueeze(0)?)?;
         let (cos, sin) = (emb.cos()?, emb.sin()?);
         let emb = if self.flip_sin_to_cos {
             Tensor::cat(&[&cos, &sin], D::Minus1)?

candle-examples/examples/stable-diffusion/main.rs

@@ -181,19 +181,29 @@ fn run(args: Args) -> Result<()> {
     let device = candle_examples::device(cpu)?;
 
     let tokenizer = Tokenizer::from_file(tokenizer).map_err(E::msg)?;
+    let pad_id = match tokenizer.get_padding() {
+        Some(padding) => padding.pad_id,
+        None => *tokenizer.get_vocab(true).get("<|endoftext|>").unwrap(),
+    };
     println!("Running with prompt \"{prompt}\".");
-    let tokens = tokenizer
+    let mut tokens = tokenizer
         .encode(prompt, true)
         .map_err(E::msg)?
         .get_ids()
         .to_vec();
+    while tokens.len() < sd_config.clip.max_position_embeddings {
+        tokens.push(pad_id)
+    }
     let tokens = Tensor::new(tokens.as_slice(), &device)?.unsqueeze(0)?;
 
-    let uncond_tokens = tokenizer
+    let mut uncond_tokens = tokenizer
         .encode(uncond_prompt, true)
         .map_err(E::msg)?
         .get_ids()
         .to_vec();
+    while uncond_tokens.len() < sd_config.clip.max_position_embeddings {
+        uncond_tokens.push(pad_id)
+    }
     let uncond_tokens = Tensor::new(uncond_tokens.as_slice(), &device)?.unsqueeze(0)?;
 
     println!("Building the Clip transformer.");
@@ -202,6 +212,7 @@ fn run(args: Args) -> Result<()> {
     let uncond_embeddings = text_model.forward(&uncond_tokens)?;
     let text_embeddings = Tensor::cat(&[uncond_embeddings, text_embeddings], 0)?;
 
+    println!("text-embeddings: {text_embeddings:?}");
     println!("Building the autoencoder.");
     let vae = sd_config.build_vae(&vae_weights, &device)?;
     println!("Building the unet.");

candle-examples/examples/stable-diffusion/resnet.rs

@@ -118,7 +118,7 @@ impl ResnetBlock2D {
                 .forward(&nn::ops::silu(temb)?)?
                 .unsqueeze(D::Minus1)?
                 .unsqueeze(D::Minus1)?
-                .add(&xs)?,
+                .broadcast_add(&xs)?,
             _ => xs,
         };
         let xs = self