[mps/inductor] Add support for sign(). (pytorch#144298)

Drive-by fix of a test name while I was at it.

Pull Request resolved: pytorch#144298
Approved by: https://github.com/malfet

Author: dcci

test/inductor/test_mps_basic.py

@@ -74,9 +74,12 @@ def test_acos(self):
     def test_atanh(self):
         self.common(lambda x: x.atanh(), (torch.rand(1024),))
 
-    def floor(self):
+    def test_floor(self):
         self.common(lambda x: x.floor(), (torch.rand(1024),))
 
+    def test_sign(self):
+        self.common(lambda x: x.sign(), (torch.rand(1024),))
+
     def test_sliced_input(self):
         self.common(
             lambda x: x[:, ::2].sin() + x[:, 1::2].cos(), (torch.rand(32, 1024),)

torch/_inductor/codegen/mps.py

@@ -194,6 +194,10 @@ def floordiv(a: CSEVariable, b: CSEVariable) -> str:
     def floor(x: CSEVariable) -> str:
         return f"metal::floor({x})"
 
+    @staticmethod
+    def sign(x: CSEVariable) -> str:
+        return f"metal::sign({x})"
+
 
 class MetalKernel(SIMDKernel):
     overrides = MetalOverrides  # type: ignore[assignment]