Fixed minor issues for bmm/mm decompositon (#109836)

Summary:

* Fixed minor issues for bmm/mm decompositon
* enabled addmm for inductor

Test Plan: ci

Reviewed By: mikekgfb

Differential Revision: D49522332

torch/_inductor/decomposition.py

@@ -179,8 +179,9 @@ def round_dec(x, decimals=0):
 
 
 @register_decomposition([aten.bmm])
+@pw_cast_for_opmath
 def bmm(self, batch2):
-    if self.device == "cpu":
+    if self.device.type == "cpu":
         if self.size(1) == 1 and batch2.size(-1) == 1:
             return torch.sum(
                 self.squeeze(1) * batch2.squeeze(-1), dim=1, keepdim=True
@@ -189,15 +190,17 @@ def bmm(self, batch2):
 
 
 @register_decomposition([aten.mm])
+@pw_cast_for_opmath
 def mm(self, input2):
     # Our matrix vector multiplies only achieve peak bandwidth with coordinate descent tuning.
     # todo: Look into why and fix it (hopefully)
     if config.coordinate_descent_tuning:
         if self.shape[0] == 1 or input2.shape[1] == 1:
             return (self.unsqueeze(2) * input2.unsqueeze(0)).sum(dim=1)
-    if self.device == "cpu":
+    if self.device.type == "cpu":
         if (
             self.size(-1) == 1
+            and self.size(0) > 0
             and input2.size(0) == 1
             and (self.dtype == input2.dtype)
             and ((torch.numel(self) + torch.numel(input2)) <= 32)