readd xformers attnblock

modules/sd_hijack_optimizations.py

@@ -292,3 +292,18 @@ def cross_attention_attnblock_forward(self, x):
 
         return h3
     
+def xformers_attnblock_forward(self, x):
+    try:
+        h_ = x
+        h_ = self.norm(h_)
+        q = self.q(h_)
+        k = self.k(h_)
+        v = self.v(h_)
+        b, c, h, w = q.shape
+        q, k, v = map(lambda t: rearrange(t, 'b c h w -> b (h w) c'), (q, k, v))
+        out = xformers.ops.memory_efficient_attention(q, k, v)
+        out = rearrange(out, 'b (h w) c -> b c h w', h=h)
+        out = self.proj_out(out)
+        return x + out
+    except NotImplementedError:
+        return cross_attention_attnblock_forward(self, x)