[Bug libfortran/93871] COTAN is slow for complex types

[sgk at troutmask dot apl.washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93871

--- Comment #8 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Fri, Feb 21, 2020 at 08:19:01PM +0000, sgk at troutmask dot
apl.washington.edu wrote:
> 
> program foo
>   complex, parameter :: z = cotan((1.,1.))
>   print *, z
> end program foo
> 

Something is definitely broken.  I'll need to
revisit intrinsic.c.  To get to the first
executable statement in gfc_simplify_cotan,

(gdb) b simplify.c:7793
(gdb) p *x
$6 = {expr_type = EXPR_FUNCTION, ts = {type = BT_UNKNOWN, kind = 0, u =
{derived = 0x0, 
      cl = 0x0, pad = 0}, interface = 0x0, is_c_interop = 0, is_iso_c = 0, 
    f90_type = BT_UNKNOWN, deferred = false, interop_kind = 0x0}, rank = 0,
shape = 0x0, 
  symtree = 0x2024e8570, ref = 0x0, where = {nextc = 0x202db65cc, lb =
0x202db6540}, 
  base_expr = 0x0, is_snan = 0, error = 0, user_operator = 0, mold = 0,
must_finalize = 0, 
  no_bounds_check = 0, external_blas = 0, do_not_resolve_again = 0, do_not_warn
= 0, 
  from_constructor = 0, representation = {length = 0, string = 0x0}, boz = {len
= 0, 
    rdx = 0, str = 0x0}, value = {logical = 38700448, iokind = 38700448,
integer = {{
        _mp_alloc = 38700448, _mp_size = 2, _mp_d = 0x0}}, real = {{
        _mpfr_prec = 8628635040, _mpfr_sign = 0, _mpfr_exp = 8647423552,
_mpfr_d = 0x0}}, 
    complex = {{re = {{_mpfr_prec = 8628635040, _mpfr_sign = 0, _mpfr_exp =
8647423552, 
            _mpfr_d = 0x0}}, im = {{_mpfr_prec = 0, _mpfr_sign = 0, _mpfr_exp =
0, 
            _mpfr_d = 0x0}}}}, op = {op = 38700448, uop = 0x0, op1 =
0x2036d3640, 
      op2 = 0x0}, function = {actual = 0x2024e85a0, name = 0x0, isym =
0x2036d3640, 
      esym = 0x0}, compcall = {actual = 0x2024e85a0, name = 0x0, 
      base_object = 0x2036d3640, tbp = 0x0, ignore_pass = 0, assign = 0},
character = {
      length = 8628635040, string = 0x0}, constructor = 0x2024e85a0},
param_list = 0x0}

Hmmm, x should be the argument to cotan.

(gdb) p *x->value.function->isym
$9 = {name = 0x20344fa88 "cotan", lib_name = 0x20346a130 "_gfortran_cotan", 
  formal = 0x2036e6928, ts = {type = BT_REAL, kind = 4, u = {derived = 0x0, cl
= 0x0, 
      pad = 0}, interface = 0x0, is_c_interop = 0, is_iso_c = 0, f90_type =
BT_UNKNOWN, 
    deferred = false, interop_kind = 0x0}, elemental = 1, inquiry = 0, 
  transformational = 0, pure = 1, generic = 1, specific = 1, actual_ok = 1,
noreturn = 0, 

but it apprears to be the function itself!

(gdb) p *x->value.function->actual->expr
$11 = {expr_type = EXPR_CONSTANT, ts = {type = BT_COMPLEX, kind = 4, u =
{derived = 0x0, 
      cl = 0x0, pad = 0}, interface = 0x0, is_c_interop = 0, is_iso_c = 0,