Add argument to skip the output reshaping in the attention functions.

comfy/ldm/modules/attention.py

@@ -89,7 +89,7 @@ class FeedForward(nn.Module):
 def Normalize(in_channels, dtype=None, device=None):
     return torch.nn.GroupNorm(num_groups=32, num_channels=in_channels, eps=1e-6, affine=True, dtype=dtype, device=device)
 
-def attention_basic(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False):
+def attention_basic(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False, skip_output_reshape=False):
     attn_precision = get_attn_precision(attn_precision)
 
     if skip_reshape:
@@ -142,16 +142,23 @@ def attention_basic(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
     sim = sim.softmax(dim=-1)
 
     out = einsum('b i j, b j d -> b i d', sim.to(v.dtype), v)
-    out = (
-        out.unsqueeze(0)
-        .reshape(b, heads, -1, dim_head)
-        .permute(0, 2, 1, 3)
-        .reshape(b, -1, heads * dim_head)
-    )
+
+    if skip_output_reshape:
+        out = (
+            out.unsqueeze(0)
+            .reshape(b, heads, -1, dim_head)
+        )
+    else:
+        out = (
+            out.unsqueeze(0)
+            .reshape(b, heads, -1, dim_head)
+            .permute(0, 2, 1, 3)
+            .reshape(b, -1, heads * dim_head)
+        )
     return out
 
 
-def attention_sub_quad(query, key, value, heads, mask=None, attn_precision=None, skip_reshape=False):
+def attention_sub_quad(query, key, value, heads, mask=None, attn_precision=None, skip_reshape=False, skip_output_reshape=False):
     attn_precision = get_attn_precision(attn_precision)
 
     if skip_reshape:
@@ -215,11 +222,13 @@ def attention_sub_quad(query, key, value, heads, mask=None, attn_precision=None,
     )
 
     hidden_states = hidden_states.to(dtype)
-
-    hidden_states = hidden_states.unflatten(0, (-1, heads)).transpose(1,2).flatten(start_dim=2)
+    if skip_output_reshape:
+        hidden_states = hidden_states.unflatten(0, (-1, heads))
+    else:
+        hidden_states = hidden_states.unflatten(0, (-1, heads)).transpose(1,2).flatten(start_dim=2)
     return hidden_states
 
-def attention_split(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False):
+def attention_split(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False, skip_output_reshape=False):
     attn_precision = get_attn_precision(attn_precision)
 
     if skip_reshape:
@@ -326,12 +335,18 @@ def attention_split(q, k, v, heads, mask=None, attn_precision=None, skip_reshape
 
     del q, k, v
 
-    r1 = (
-        r1.unsqueeze(0)
-        .reshape(b, heads, -1, dim_head)
-        .permute(0, 2, 1, 3)
-        .reshape(b, -1, heads * dim_head)
-    )
+    if skip_output_reshape:
+        r1 = (
+            r1.unsqueeze(0)
+            .reshape(b, heads, -1, dim_head)
+        )
+    else:
+        r1 = (
+            r1.unsqueeze(0)
+            .reshape(b, heads, -1, dim_head)
+            .permute(0, 2, 1, 3)
+            .reshape(b, -1, heads * dim_head)
+        )
     return r1
 
 BROKEN_XFORMERS = False
@@ -342,7 +357,7 @@ try:
 except:
     pass
 
-def attention_xformers(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False):
+def attention_xformers(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False, skip_output_reshape=False):
     b = q.shape[0]
     dim_head = q.shape[-1]
     # check to make sure xformers isn't broken
@@ -395,9 +410,12 @@ def attention_xformers(q, k, v, heads, mask=None, attn_precision=None, skip_resh
 
     out = xformers.ops.memory_efficient_attention(q, k, v, attn_bias=mask)
 
-    out = (
-        out.reshape(b, -1, heads * dim_head)
-    )
+    if skip_output_reshape:
+        out = out.permute(0, 2, 1, 3)
+    else:
+        out = (
+            out.reshape(b, -1, heads * dim_head)
+        )
 
     return out
 
@@ -408,7 +426,7 @@ else:
     SDP_BATCH_LIMIT = 2**31
 
 
-def attention_pytorch(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False):
+def attention_pytorch(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False, skip_output_reshape=False):
     if skip_reshape:
         b, _, _, dim_head = q.shape
     else:
@@ -429,9 +447,10 @@ def attention_pytorch(q, k, v, heads, mask=None, attn_precision=None, skip_resha
 
     if SDP_BATCH_LIMIT >= b:
         out = torch.nn.functional.scaled_dot_product_attention(q, k, v, attn_mask=mask, dropout_p=0.0, is_causal=False)
-        out = (
-            out.transpose(1, 2).reshape(b, -1, heads * dim_head)
-        )
+        if not skip_output_reshape:
+            out = (
+                out.transpose(1, 2).reshape(b, -1, heads * dim_head)
+            )
     else:
         out = torch.empty((b, q.shape[2], heads * dim_head), dtype=q.dtype, layout=q.layout, device=q.device)
         for i in range(0, b, SDP_BATCH_LIMIT):
@@ -450,7 +469,7 @@ def attention_pytorch(q, k, v, heads, mask=None, attn_precision=None, skip_resha
     return out
 
 
-def attention_sage(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False):
+def attention_sage(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=False, skip_output_reshape=False):
     if skip_reshape:
         b, _, _, dim_head = q.shape
         tensor_layout="HND"
@@ -473,11 +492,15 @@ def attention_sage(q, k, v, heads, mask=None, attn_precision=None, skip_reshape=
 
     out = sageattn(q, k, v, attn_mask=mask, is_causal=False, tensor_layout=tensor_layout)
     if tensor_layout == "HND":
-        out = (
-            out.transpose(1, 2).reshape(b, -1, heads * dim_head)
-        )
+        if not skip_output_reshape:
+            out = (
+                out.transpose(1, 2).reshape(b, -1, heads * dim_head)
+            )
     else:
-        out = out.reshape(b, -1, heads * dim_head)
+        if skip_output_reshape:
+            out = out.transpose(1, 2)
+        else:
+            out = out.reshape(b, -1, heads * dim_head)
     return out