python_alu sin(inf) is nan (#5020)

* python_alu sin(inf) is nan

without special handling, it throws ValueError: math domain error

* skip CUDACPU

test/test_ops.py

@@ -474,6 +474,9 @@ def test_rshift(self):
   def test_sin(self):
     helper_test_op([(45,65)], lambda x: x.sin())
     helper_test_op([()], lambda x: x.sin())
+    # works on real CUDA but not CUDACPU
+    if not (getenv("CUDACPU") or (getenv("MOCKGPU") and Device.DEFAULT == "NV")):
+      helper_test_op(None, lambda x: x.sin(), vals=[[math.nan, math.inf, -math.inf]])
   def test_cos(self):
     helper_test_op([(45,65)], lambda x: x.cos())
     helper_test_op([()], lambda x: x.cos())

tinygrad/ops.py

@@ -118,7 +118,8 @@ def wfxn(*args):
 python_alu = {
   UnaryOps.LOG2: lambda x: math.log2(x) if x > 0 else -math.inf if x == 0 else math.nan,
   UnaryOps.EXP2: hook_overflow(math.inf, lambda x: math.exp(x*math.log(2))),
-  UnaryOps.SQRT: lambda x: math.sqrt(x) if x >= 0 else math.nan, UnaryOps.SIN: math.sin,
+  UnaryOps.SQRT: lambda x: math.sqrt(x) if x >= 0 else math.nan,
+  UnaryOps.SIN: lambda x: math.sin(x) if not math.isinf(x) else math.nan,
   UnaryOps.RECIP: lambda x: 1/x if x != 0 else float('inf'),
   UnaryOps.NEG: lambda x: (not x) if isinstance(x, bool) else -x,
   BinaryOps.SHR: operator.rshift, BinaryOps.SHL: operator.lshift,