New flag -fdec-math for COTAN and degree trig intrinsics.

2016-10-11  Fritz Reese  <fritzoreese@gmail.com>

New flag -fdec-math for COTAN and degree trig intrinsics.

	gcc/fortran/
	* lang.opt: New flag -fdec-math.
	* options.c (set_dec_flags): Enable with -fdec.
	* invoke.texi, gfortran.texi, intrinsic.texi: Update documentation.
	* intrinsics.c (add_functions, do_simplify): New intrinsics
	with -fdec-math.
	* gfortran.h (gfc_isym_id): New isym GFC_ISYM_COTAN.
	* gfortran.h (gfc_resolve_atan2d, gfc_resolve_cotan,
	gfc_resolve_trigd, gfc_resolve_atrigd): New prototypes.
	* iresolve.c (resolve_trig_call, get_degrees, get_radians,
	is_trig_resolved, gfc_resolve_cotan, gfc_resolve_trigd,
	gfc_resolve_atrigd, gfc_resolve_atan2d): New functions.
	* intrinsics.h (gfc_simplify_atan2d, gfc_simplify_atrigd,
	gfc_simplify_cotan, gfc_simplify_trigd): New prototypes.
	* simplify.c (simplify_trig_call, degrees_f, radians_f,
	gfc_simplify_cotan, gfc_simplify_trigd, gfc_simplify_atrigd,
	gfc_simplify_atan2d): New functions.

	gcc/testsuite/gfortran.dg/
	* dec_math.f90: New testsuite.

From-SVN: r240989

1 files changed, 233 insertions, 0 deletions

diff --git a/gcc/fortran/iresolve.c b/gcc/fortran/iresolve.c
index ecea1c3..f4f81b2 100644
--- a/gcc/fortran/iresolve.c
+++ b/gcc/fortran/iresolve.c
@@ -673,6 +673,86 @@ gfc_resolve_cosh (gfc_expr *f, gfc_expr *x)
 }
 
 
+/* Our replacement of elements of a trig call with an EXPR_OP (e.g.
+   multiplying the result or operands by a factor to convert to/from degrees)
+   will cause the resolve_* function to be invoked again when resolving the
+   freshly created EXPR_OP.  See gfc_resolve_trigd, gfc_resolve_atrigd,
+   gfc_resolve_cotan.  We must observe this and avoid recursively creating
+   layers of nested EXPR_OP expressions.  */
+
+static bool
+is_trig_resolved (gfc_expr *f)
+{
+  /* We know we've already resolved the function if we see the lib call
+     starting with '__'.  */
+  return f->value.function.name != NULL
+    && 0 == strncmp ("__", f->value.function.name, 2);
+}
+
+/* Return a shallow copy of the function expression f.  The original expression
+   has its pointers cleared so that it may be freed without affecting the
+   shallow copy.  This is similar to gfc_copy_expr, but doesn't perform a deep
+   copy of the argument list, allowing it to be reused somewhere else,
+   setting the expression up nicely for gfc_replace_expr.  */
+
+static gfc_expr *
+copy_replace_function_shallow (gfc_expr *f)
+{
+  gfc_expr *fcopy;
+  gfc_actual_arglist *args;
+
+  /* The only thing deep-copied in gfc_copy_expr is args.  */
+  args = f->value.function.actual;
+  f->value.function.actual = NULL;
+  fcopy = gfc_copy_expr (f);
+  fcopy->value.function.actual = args;
+
+  /* Clear the old function so the shallow copy is not affected if the old
+     expression is freed.  */
+  f->value.function.name = NULL;
+  f->value.function.isym = NULL;
+  f->value.function.actual = NULL;
+  f->value.function.esym = NULL;
+  f->shape = NULL;
+  f->ref = NULL;
+
+  return fcopy;
+}
+
+
+/* Resolve cotan = cos / sin.  */
+
+void
+gfc_resolve_cotan (gfc_expr *f, gfc_expr *x)
+{
+  gfc_expr *result, *fcopy, *sin;
+  gfc_actual_arglist *sin_args;
+
+  if (is_trig_resolved (f))
+    return;
+
+  /* Compute cotan (x) = cos (x) / sin (x).  */
+  f->value.function.isym = gfc_intrinsic_function_by_id (GFC_ISYM_COS);
+  gfc_resolve_cos (f, x);
+
+  sin_args = gfc_get_actual_arglist ();
+  sin_args->expr = gfc_copy_expr (x);
+
+  sin = gfc_get_expr ();
+  sin->ts = f->ts;
+  sin->where = f->where;
+  sin->expr_type = EXPR_FUNCTION;
+  sin->value.function.isym = gfc_intrinsic_function_by_id (GFC_ISYM_SIN);
+  sin->value.function.actual = sin_args;
+  gfc_resolve_sin (sin, sin_args->expr);
+
+  /* Replace f with cos/sin - we do this in place in f for the caller.  */
+  fcopy = copy_replace_function_shallow (f);
+  result = gfc_divide (fcopy, sin);
+  gfc_replace_expr (f, result);
+}
+
+
 void
 gfc_resolve_count (gfc_expr *f, gfc_expr *mask, gfc_expr *dim, gfc_expr *kind)
 {
@@ -2578,6 +2658,159 @@ gfc_resolve_tanh (gfc_expr *f, gfc_expr *x)
 }
 
 
+/* Build an expression for converting degrees to radians.  */
+
+static gfc_expr *
+get_radians (gfc_expr *deg)
+{
+  gfc_expr *result, *factor;
+  gfc_actual_arglist *mod_args;
+
+  gcc_assert (deg->ts.type == BT_REAL);
+
+  /* Set deg = deg % 360 to avoid offsets from large angles.  */
+  factor = gfc_get_constant_expr (deg->ts.type, deg->ts.kind, &deg->where);
+  mpfr_set_d (factor->value.real, 360.0, GFC_RND_MODE);
+
+  mod_args = gfc_get_actual_arglist ();
+  mod_args->expr = deg;
+  mod_args->next = gfc_get_actual_arglist ();
+  mod_args->next->expr = factor;
+
+  result = gfc_get_expr ();
+  result->ts = deg->ts;
+  result->where = deg->where;
+  result->expr_type = EXPR_FUNCTION;
+  result->value.function.isym = gfc_intrinsic_function_by_id (GFC_ISYM_MOD);
+  result->value.function.actual = mod_args;
+
+  /* Set factor = pi / 180.  */
+  factor = gfc_get_constant_expr (deg->ts.type, deg->ts.kind, &deg->where);
+  mpfr_const_pi (factor->value.real, GFC_RND_MODE);
+  mpfr_div_d (factor->value.real, factor->value.real, 180.0, GFC_RND_MODE);
+
+  /* Result is rad = (deg % 360) * (pi / 180).  */
+  result = gfc_multiply (result, factor);
+  return result;
+}
+
+
+/* Build an expression for converting radians to degrees.  */
+
+static gfc_expr *
+get_degrees (gfc_expr *rad)
+{
+  gfc_expr *result, *factor;
+  gfc_actual_arglist *mod_args;
+
+  gcc_assert (rad->ts.type == BT_REAL);
+
+  /* Set rad = rad % 2pi to avoid offsets from large angles.  */
+  factor = gfc_get_constant_expr (rad->ts.type, rad->ts.kind, &rad->where);
+  mpfr_const_pi (factor->value.real, GFC_RND_MODE);
+  mpfr_mul_ui (factor->value.real, factor->value.real, 2, GFC_RND_MODE);
+
+  mod_args = gfc_get_actual_arglist ();
+  mod_args->expr = rad;
+  mod_args->next = gfc_get_actual_arglist ();
+  mod_args->next->expr = factor;
+
+  result = gfc_get_expr ();
+  result->ts = rad->ts;
+  result->where = rad->where;
+  result->expr_type = EXPR_FUNCTION;
+  result->value.function.isym = gfc_intrinsic_function_by_id (GFC_ISYM_MOD);
+  result->value.function.actual = mod_args;
+
+  /* Set factor = 180 / pi.  */
+  factor = gfc_get_constant_expr (rad->ts.type, rad->ts.kind, &rad->where);
+  mpfr_set_d (factor->value.real, 180.0, GFC_RND_MODE);
+  mpfr_init (tmp);
+  mpfr_const_pi (tmp, GFC_RND_MODE);
+  mpfr_div (factor->value.real, factor->value.real, tmp, GFC_RND_MODE);
+  mpfr_clear (tmp);
+
+  /* Result is deg = (rad % 2pi) * (180 / pi).  */
+  result = gfc_multiply (result, factor);
+  return result;
+}
+
+
+/* Resolve a call to a trig function.  */
+
+static void
+resolve_trig_call (gfc_expr *f, gfc_expr *x)
+{
+  switch (f->value.function.isym->id)
+    {
+      case GFC_ISYM_ACOS:
+	return gfc_resolve_acos (f, x);
+      case GFC_ISYM_ASIN:
+	return gfc_resolve_asin (f, x);
+      case GFC_ISYM_ATAN:
+	return gfc_resolve_atan (f, x);
+      case GFC_ISYM_ATAN2:
+	/* NB. arg3 is unused for atan2 */
+	return gfc_resolve_atan2 (f, x, NULL);
+      case GFC_ISYM_COS:
+	return gfc_resolve_cos (f, x);
+      case GFC_ISYM_COTAN:
+	return gfc_resolve_cotan (f, x);
+      case GFC_ISYM_SIN:
+	return gfc_resolve_sin (f, x);
+      case GFC_ISYM_TAN:
+	return gfc_resolve_tan (f, x);
+      default:
+	break;
+    }
+
+  gcc_unreachable ();
+}
+
+/* Resolve degree trig function as trigd (x) = trig (radians (x)).  */
+
+void
+gfc_resolve_trigd (gfc_expr *f, gfc_expr *x)
+{
+  if (is_trig_resolved (f))
+    return;
+
+  x = get_radians (x);
+  f->value.function.actual->expr = x;
+
+  resolve_trig_call (f, x);
+}
+
+
+/* Resolve degree inverse trig function as atrigd (x) = degrees (atrig (x)).  */
+
+void
+gfc_resolve_atrigd (gfc_expr *f, gfc_expr *x)
+{
+  gfc_expr *result, *fcopy;
+
+  if (is_trig_resolved (f))
+    return;
+
+  resolve_trig_call (f, x);
+
+  fcopy = copy_replace_function_shallow (f);
+  result = get_degrees (fcopy);
+  gfc_replace_expr (f, result);
+}
+
+
+/* Resolve atan2d(x) = degrees(atan2(x)).  */
+
+void
+gfc_resolve_atan2d (gfc_expr *f, gfc_expr *x, gfc_expr *y ATTRIBUTE_UNUSED)
+{
+  /* Note that we lose the second arg here - that's okay because it is
+     unused in gfc_resolve_atan2 anyway.  */
+  gfc_resolve_atrigd (f, x);
+}
+
+
 void
 gfc_resolve_image_index (gfc_expr *f, gfc_expr *array ATTRIBUTE_UNUSED,
 			 gfc_expr *sub ATTRIBUTE_UNUSED)