Remove unary_sqrt_extern() used for sqrt_impl (#87)

This possibly could be a function required to move to upstream but also
it could be a not intended function.

This function was created in b4a325d by @DrTodd13.
Then there was a long branch dedicated to PVC and in
947b407 it was merged with master of Numba bu @reazul.hoque.
It was released in 0.49.1+dppy0.4.0.

Author: PokhodenkoSA

numba/cpython/mathimpl.py

@@ -171,45 +171,6 @@ def float_impl(context, builder, sig, args):
 
     return float_impl
 
-def unary_sqrt_extern(fn, int_restype=False):
-    """
-    Register implementations of Python function *fn* using the
-    external function named *f32extern* and *f64extern* (for float32
-    and float64 inputs, respectively).
-    If *int_restype* is true, then the function's return value should be
-    integral, otherwise floating-point.
-    """
-    f_restype = types.int64 if int_restype else None
-
-    def float_impl(context, builder, sig, args):
-        """
-        Implement *fn* for a types.Float input.
-        """
-        [val] = args
-        mod = builder.module
-        input_type = sig.args[0]
-        lty = context.get_value_type(input_type)
-        sqrt32extern = getattr(context, 'sqrt32extern', "sqrtf")
-        sqrt64extern = getattr(context, 'sqrt64extern', "sqrt")
-
-        func_name = {
-            types.float32: sqrt32extern,
-            types.float64: sqrt64extern,
-            }[input_type]
-        fnty = Type.function(lty, [lty])
-        fn = cgutils.insert_pure_function(builder.module, fnty, name=func_name)
-        res = builder.call(fn, (val,))
-        res = context.cast(builder, res, input_type, sig.return_type)
-        return impl_ret_untracked(context, builder, sig.return_type, res)
-
-    lower(fn, types.Float)(float_impl)
-
-    # Implement wrapper for integer inputs
-    unary_math_int_impl(fn, float_impl)
-
-    return float_impl
-
-
 
 unary_math_intr(math.fabs, lc.INTR_FABS)
 #unary_math_intr(math.sqrt, lc.INTR_SQRT)
@@ -244,8 +205,7 @@ def float_impl(context, builder, sig, args):
 floor_impl = unary_math_extern(math.floor, "floorf", "floor", True)
 
 gamma_impl = unary_math_extern(math.gamma, "numba_gammaf", "numba_gamma") # work-around
-sqrt_impl = unary_sqrt_extern(math.sqrt)
-#sqrt_impl = unary_math_extern(math.sqrt, "sqrtf", "sqrt")
+sqrt_impl = unary_math_extern(math.sqrt, "sqrtf", "sqrt")
 trunc_impl = unary_math_extern(math.trunc, "truncf", "trunc", True)
 lgamma_impl = unary_math_extern(math.lgamma, "lgammaf", "lgamma")