Support unittest for Z-image ⚡️ (#12715)

* Add Support for Z-Image.

* Reformatting with make style, black & isort.

* Remove init, Modify import utils, Merge forward in transformers block, Remove once func in pipeline.

* modified main model forward, freqs_cis left

* refactored to add B dim

* fixed stack issue

* fixed modulation bug

* fixed modulation bug

* fix bug

* remove value_from_time_aware_config

* styling

* Fix neg embed and devide / bug; Reuse pad zero tensor; Turn cat -> repeat; Add hint for attn processor.

* Replace padding with pad_sequence; Add gradient checkpointing.

* Fix flash_attn3 in dispatch attn backend by _flash_attn_forward, replace its origin implement; Add DocString in pipeline for that.

* Fix Docstring and Make Style.

* Revert "Fix flash_attn3 in dispatch attn backend by _flash_attn_forward, replace its origin implement; Add DocString in pipeline for that."

This reverts commit fbf26b7.

* update z-image docstring

* Revert attention dispatcher

* update z-image docstring

* styling

* Recover attention_dispatch.py with its origin impl, later would special commit for fa3 compatibility.

* Fix prev bug, and support for prompt_embeds pass in args after prompt pre-encode as List of torch Tensor.

* Remove einop dependency.

* remove redundant imports & make fix-copies

* fix import

* Support for num_images_per_prompt>1; Remove redundant unquote variables.

* Fix bugs for num_images_per_prompt with actual batch.

* Add unit tests for Z-Image.

* Refine unitest and skip for cases needed separate test env; Fix compatibility with unitest in model, mostly precision formating.

* Add clean env for test_save_load_float16 separ test; Add Note; Styling.

* Update dtype mentioned by yiyi.

---------

Co-authored-by: liudongyang <[email protected]>

Author: JerryWu-code

src/diffusers/models/transformers/transformer_z_image.py

@@ -69,7 +69,10 @@ def timestep_embedding(t, dim, max_period=10000):
 
     def forward(self, t):
         t_freq = self.timestep_embedding(t, self.frequency_embedding_size)
-        t_emb = self.mlp(t_freq.to(self.mlp[0].weight.dtype))
+        weight_dtype = self.mlp[0].weight.dtype
+        if weight_dtype.is_floating_point:
+            t_freq = t_freq.to(weight_dtype)
+        t_emb = self.mlp(t_freq)
         return t_emb
 
 
@@ -126,6 +129,10 @@ def apply_rotary_emb(x_in: torch.Tensor, freqs_cis: torch.Tensor) -> torch.Tenso
         dtype = query.dtype
         query, key = query.to(dtype), key.to(dtype)
 
+        # From [batch, seq_len] to [batch, 1, 1, seq_len] -> broadcast to [batch, heads, seq_len, seq_len]
+        if attention_mask is not None and attention_mask.ndim == 2:
+            attention_mask = attention_mask[:, None, None, :]
+
         # Compute joint attention
         hidden_states = dispatch_attention_fn(
             query,
@@ -306,6 +313,10 @@ def __call__(self, ids: torch.Tensor):
         if self.freqs_cis is None:
             self.freqs_cis = self.precompute_freqs_cis(self.axes_dims, self.axes_lens, theta=self.theta)
             self.freqs_cis = [freqs_cis.to(device) for freqs_cis in self.freqs_cis]
+        else:
+            # Ensure freqs_cis are on the same device as ids
+            if self.freqs_cis[0].device != device:
+                self.freqs_cis = [freqs_cis.to(device) for freqs_cis in self.freqs_cis]
 
         result = []
         for i in range(len(self.axes_dims)):
@@ -317,6 +328,7 @@ def __call__(self, ids: torch.Tensor):
 class ZImageTransformer2DModel(ModelMixin, ConfigMixin, PeftAdapterMixin, FromOriginalModelMixin):
     _supports_gradient_checkpointing = True
     _no_split_modules = ["ZImageTransformerBlock"]
+    _skip_layerwise_casting_patterns = ["t_embedder", "cap_embedder"]  # precision sensitive layers
 
     @register_to_config
     def __init__(
@@ -553,8 +565,6 @@ def forward(
         t = t * self.t_scale
         t = self.t_embedder(t)
 
-        adaln_input = t
-
         (
             x,
             cap_feats,
@@ -572,6 +582,9 @@ def forward(
 
         x = torch.cat(x, dim=0)
         x = self.all_x_embedder[f"{patch_size}-{f_patch_size}"](x)
+
+        # Match t_embedder output dtype to x for layerwise casting compatibility
+        adaln_input = t.type_as(x)
         x[torch.cat(x_inner_pad_mask)] = self.x_pad_token
         x = list(x.split(x_item_seqlens, dim=0))
         x_freqs_cis = list(self.rope_embedder(torch.cat(x_pos_ids, dim=0)).split(x_item_seqlens, dim=0))

src/diffusers/pipelines/z_image/pipeline_z_image.py

@@ -165,21 +165,16 @@ def encode_prompt(
         self,
         prompt: Union[str, List[str]],
         device: Optional[torch.device] = None,
-        dtype: Optional[torch.dtype] = None,
-        num_images_per_prompt: int = 1,
         do_classifier_free_guidance: bool = True,
         negative_prompt: Optional[Union[str, List[str]]] = None,
         prompt_embeds: Optional[List[torch.FloatTensor]] = None,
         negative_prompt_embeds: Optional[torch.FloatTensor] = None,
         max_sequence_length: int = 512,
-        lora_scale: Optional[float] = None,
     ):
         prompt = [prompt] if isinstance(prompt, str) else prompt
         prompt_embeds = self._encode_prompt(
             prompt=prompt,
             device=device,
-            dtype=dtype,
-            num_images_per_prompt=num_images_per_prompt,
             prompt_embeds=prompt_embeds,
             max_sequence_length=max_sequence_length,
         )
@@ -193,8 +188,6 @@ def encode_prompt(
             negative_prompt_embeds = self._encode_prompt(
                 prompt=negative_prompt,
                 device=device,
-                dtype=dtype,
-                num_images_per_prompt=num_images_per_prompt,
                 prompt_embeds=negative_prompt_embeds,
                 max_sequence_length=max_sequence_length,
             )
@@ -206,12 +199,9 @@ def _encode_prompt(
         self,
         prompt: Union[str, List[str]],
         device: Optional[torch.device] = None,
-        dtype: Optional[torch.dtype] = None,
-        num_images_per_prompt: int = 1,
         prompt_embeds: Optional[List[torch.FloatTensor]] = None,
         max_sequence_length: int = 512,
     ) -> List[torch.FloatTensor]:
-        assert num_images_per_prompt == 1
         device = device or self._execution_device
 
         if prompt_embeds is not None:
@@ -417,8 +407,6 @@ def __call__(
                 f"Please adjust the width to a multiple of {vae_scale}."
             )
 
-        assert self.dtype == torch.bfloat16
-        dtype = self.dtype
         device = self._execution_device
 
         self._guidance_scale = guidance_scale
@@ -434,10 +422,6 @@ def __call__(
         else:
             batch_size = len(prompt_embeds)
 
-        lora_scale = (
-            self.joint_attention_kwargs.get("scale", None) if self.joint_attention_kwargs is not None else None
-        )
-
         # If prompt_embeds is provided and prompt is None, skip encoding
         if prompt_embeds is not None and prompt is None:
             if self.do_classifier_free_guidance and negative_prompt_embeds is None:
@@ -455,11 +439,8 @@ def __call__(
                 do_classifier_free_guidance=self.do_classifier_free_guidance,
                 prompt_embeds=prompt_embeds,
                 negative_prompt_embeds=negative_prompt_embeds,
-                dtype=dtype,
                 device=device,
-                num_images_per_prompt=num_images_per_prompt,
                 max_sequence_length=max_sequence_length,
-                lora_scale=lora_scale,
             )
 
         # 4. Prepare latent variables
@@ -475,6 +456,14 @@ def __call__(
             generator,
             latents,
         )
+
+        # Repeat prompt_embeds for num_images_per_prompt
+        if num_images_per_prompt > 1:
+            prompt_embeds = [pe for pe in prompt_embeds for _ in range(num_images_per_prompt)]
+            if self.do_classifier_free_guidance and negative_prompt_embeds:
+                negative_prompt_embeds = [npe for npe in negative_prompt_embeds for _ in range(num_images_per_prompt)]
+
+        actual_batch_size = batch_size * num_images_per_prompt
         image_seq_len = (latents.shape[2] // 2) * (latents.shape[3] // 2)
 
         # 5. Prepare timesteps
@@ -523,12 +512,12 @@ def __call__(
                 apply_cfg = self.do_classifier_free_guidance and current_guidance_scale > 0
 
                 if apply_cfg:
-                    latents_typed = latents if latents.dtype == dtype else latents.to(dtype)
+                    latents_typed = latents.to(self.transformer.dtype)
                     latent_model_input = latents_typed.repeat(2, 1, 1, 1)
                     prompt_embeds_model_input = prompt_embeds + negative_prompt_embeds
                     timestep_model_input = timestep.repeat(2)
                 else:
-                    latent_model_input = latents if latents.dtype == dtype else latents.to(dtype)
+                    latent_model_input = latents.to(self.transformer.dtype)
                     prompt_embeds_model_input = prompt_embeds
                     timestep_model_input = timestep
 
@@ -543,11 +532,11 @@ def __call__(
 
                 if apply_cfg:
                     # Perform CFG
-                    pos_out = model_out_list[:batch_size]
-                    neg_out = model_out_list[batch_size:]
+                    pos_out = model_out_list[:actual_batch_size]
+                    neg_out = model_out_list[actual_batch_size:]
 
                     noise_pred = []
-                    for j in range(batch_size):
+                    for j in range(actual_batch_size):
                         pos = pos_out[j].float()
                         neg = neg_out[j].float()
 
@@ -588,11 +577,11 @@ def __call__(
                 if i == len(timesteps) - 1 or ((i + 1) > num_warmup_steps and (i + 1) % self.scheduler.order == 0):
                     progress_bar.update()
 
-        latents = latents.to(dtype)
         if output_type == "latent":
             image = latents
 
         else:
+            latents = latents.to(self.vae.dtype)
             latents = (latents / self.vae.config.scaling_factor) + self.vae.config.shift_factor
 
             image = self.vae.decode(latents, return_dict=False)[0]