From 8a438115fb9e3ed8327de25b23d341dccde229d9 Mon Sep 17 00:00:00 2001
From: comfyanonymous <comfyanonymous@protonmail.com>
Date: Mon, 14 Apr 2025 18:00:33 -0400
Subject: [PATCH] add RMSNorm to comfy.ops

---
 comfy/ldm/common_dit.py | 20 ++-----------
 comfy/ops.py            | 20 +++++++++++++
 comfy/rmsnorm.py        | 65 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+), 17 deletions(-)
 create mode 100644 comfy/rmsnorm.py

diff --git a/comfy/ldm/common_dit.py b/comfy/ldm/common_dit.py
index e0f3057f..f7f56b72 100644
--- a/comfy/ldm/common_dit.py
+++ b/comfy/ldm/common_dit.py
@@ -1,5 +1,6 @@
 import torch
-import comfy.ops
+import comfy.rmsnorm
+
 
 def pad_to_patch_size(img, patch_size=(2, 2), padding_mode="circular"):
     if padding_mode == "circular" and (torch.jit.is_tracing() or torch.jit.is_scripting()):
@@ -11,20 +12,5 @@ def pad_to_patch_size(img, patch_size=(2, 2), padding_mode="circular"):
 
     return torch.nn.functional.pad(img, pad, mode=padding_mode)
 
-try:
-    rms_norm_torch = torch.nn.functional.rms_norm
-except:
-    rms_norm_torch = None
 
-def rms_norm(x, weight=None, eps=1e-6):
-    if rms_norm_torch is not None and not (torch.jit.is_tracing() or torch.jit.is_scripting()):
-        if weight is None:
-            return rms_norm_torch(x, (x.shape[-1],), eps=eps)
-        else:
-            return rms_norm_torch(x, weight.shape, weight=comfy.ops.cast_to(weight, dtype=x.dtype, device=x.device), eps=eps)
-    else:
-        r = x * torch.rsqrt(torch.mean(x**2, dim=-1, keepdim=True) + eps)
-        if weight is None:
-            return r
-        else:
-            return r * comfy.ops.cast_to(weight, dtype=x.dtype, device=x.device)
+rms_norm = comfy.rmsnorm.rms_norm
diff --git a/comfy/ops.py b/comfy/ops.py
index 9a5c1ee9..6b0e2930 100644
--- a/comfy/ops.py
+++ b/comfy/ops.py
@@ -21,6 +21,7 @@ import logging
 import comfy.model_management
 from comfy.cli_args import args, PerformanceFeature
 import comfy.float
+import comfy.rmsnorm
 
 cast_to = comfy.model_management.cast_to #TODO: remove once no more references
 
@@ -146,6 +147,25 @@ class disable_weight_init:
             else:
                 return super().forward(*args, **kwargs)
 
+    class RMSNorm(comfy.rmsnorm.RMSNorm, CastWeightBiasOp):
+        def reset_parameters(self):
+            self.bias = None
+            return None
+
+        def forward_comfy_cast_weights(self, input):
+            if self.weight is not None:
+                weight, bias = cast_bias_weight(self, input)
+            else:
+                weight = None
+            return comfy.rmsnorm.rms_norm(input, weight, self.eps)  # TODO: switch to commented out line when old torch is deprecated
+            # return torch.nn.functional.rms_norm(input, self.normalized_shape, weight, self.eps)
+
+        def forward(self, *args, **kwargs):
+            if self.comfy_cast_weights or len(self.weight_function) > 0 or len(self.bias_function) > 0:
+                return self.forward_comfy_cast_weights(*args, **kwargs)
+            else:
+                return super().forward(*args, **kwargs)
+
     class ConvTranspose2d(torch.nn.ConvTranspose2d, CastWeightBiasOp):
         def reset_parameters(self):
             return None
diff --git a/comfy/rmsnorm.py b/comfy/rmsnorm.py
new file mode 100644
index 00000000..81b3e906
--- /dev/null
+++ b/comfy/rmsnorm.py
@@ -0,0 +1,65 @@
+import torch
+import comfy.model_management
+import numbers
+
+RMSNorm = None
+
+try:
+    rms_norm_torch = torch.nn.functional.rms_norm
+    RMSNorm = torch.nn.RMSNorm
+except:
+    rms_norm_torch = None
+
+
+def rms_norm(x, weight=None, eps=1e-6):
+    if rms_norm_torch is not None and not (torch.jit.is_tracing() or torch.jit.is_scripting()):
+        if weight is None:
+            return rms_norm_torch(x, (x.shape[-1],), eps=eps)
+        else:
+            return rms_norm_torch(x, weight.shape, weight=comfy.model_management.cast_to(weight, dtype=x.dtype, device=x.device), eps=eps)
+    else:
+        r = x * torch.rsqrt(torch.mean(x**2, dim=-1, keepdim=True) + eps)
+        if weight is None:
+            return r
+        else:
+            return r * comfy.model_management.cast_to(weight, dtype=x.dtype, device=x.device)
+
+
+if RMSNorm is None:
+    class RMSNorm(torch.nn.Module):
+        def __init__(
+            self, dim: int, elementwise_affine: bool = False, eps: float = 1e-6, device=None, dtype=None, **kwargs
+        ):
+            super().__init__()
+            self.eps = eps
+            self.learnable_scale = elementwise_affine
+            if self.learnable_scale:
+                self.weight = torch.nn.Parameter(torch.empty(dim, device=device, dtype=dtype))
+            else:
+                self.register_parameter("weight", None)
+
+        def __init__(
+            self,
+            normalized_shape,
+            eps=None,
+            elementwise_affine=True,
+            device=None,
+            dtype=None,
+        ):
+            factory_kwargs = {"device": device, "dtype": dtype}
+            super().__init__()
+            if isinstance(normalized_shape, numbers.Integral):
+                # mypy error: incompatible types in assignment
+                normalized_shape = (normalized_shape,)  # type: ignore[assignment]
+            self.normalized_shape = tuple(normalized_shape)  # type: ignore[arg-type]
+            self.eps = eps
+            self.elementwise_affine = elementwise_affine
+            if self.elementwise_affine:
+                self.weight = torch.nn.Parameter(
+                    torch.empty(self.normalized_shape, **factory_kwargs)
+                )
+            else:
+                self.register_parameter("weight", None)
+
+        def forward(self, x):
+            return rms_norm(x, self.weight, self.eps)