perf: cache const UOp creation [run_process_replay] (#5156)

tinygrad/codegen/uops.py

@@ -60,6 +60,7 @@ class UOp:
   def max(self, x): return UOp.alu(BinaryOps.MAX, self, x)
   def min(self, x): return -UOp.alu(BinaryOps.MAX, -self, -x)
   @staticmethod
+  @functools.lru_cache(maxsize=None)
   def const(dtype:Optional[DType], b:ConstType|Variable):
     if isinstance(b, Variable): return UOp(UOps.DEFINE_VAR, dtype, (), b)
     return UOp(UOps.CONST, dtype, arg=dtypes.as_const(b, dtype) if dtype is not None else b)