[patch, Fortran] PR 55806 - Inefficient ANY with array constructors

[Thomas Koenig <tkoenig at netcologne dot de>]

Hello world,

the attached patch replaces ANY(a, b, c) with a .or. b .or c,
leading to reduced execution time.  It also handles ALL, PRODUCT
and SUM.

This fixes a bug noted by Michael Metcalf.

Regression-tested.  OK for trunk?

	Thomas

2013-01-01  Thomas Koenig  <tkoenig@gcc.gnu.org>

        PR fortran/55806
        * frontend-passes.c (optimize_reduction):  New function,
        including prototype.
        (callback_reduction):  Likewise.
        (gfc_run_passes):  Also run optimize_reduction.
        (copy_walk_reduction_arg):  New function.
        (dummy_code_callback):  New function.

2013-01-01  Thomas Koenig  <tkoenig@gcc.gnu.org>

        PR fortran/55806
        * gfortran.dg/array_constructor_40.f90:  New test.

! { dg-do run }
! { dg-options "-ffrontend-optimize -fdump-tree-original" }
! PR 55806 - replace ANY intrinsic for array
! constructor with .or.

module mymod
  implicit none
contains
  subroutine bar(a,b,c, lo)
    real, dimension(3,3), intent(in) :: a,b
    logical, dimension(3,3), intent(in) :: lo
    integer, intent(out) :: c
    real, parameter :: acc = 1e-4
    integer :: i,j
    
    c = 0
    do i=1,3
       if (any([abs(a(i,1) - b(i,1)) > acc,  &
            abs(a(i,2) - b(i,2)) > acc, &
            abs(a(i,3) - b(i,3)) > acc, lo(i,:), &
            (j==i+1,j=3,8)])) cycle
       c = c + i
    end do
  end subroutine bar
end module mymod

program main
  use mymod
  implicit none
  real, dimension(3,3) :: a,b
  integer :: c
  logical lo(3,3)
  data a/1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9/

  b = a
  b(2,2) = a(2,2) + 0.2
  lo = .false.
  lo(3,3) = .true.
  call bar(a,b,c,lo)
  if (c /= 1) call abort
end program main
! { dg-final { scan-tree-dump-times "while" 2 "original" } }
! { dg-final { cleanup-tree-dump "original" } }

Index: frontend-passes.c
===================================================================
--- frontend-passes.c	(Revision 194760)
+++ frontend-passes.c	(Arbeitskopie)
@@ -40,6 +40,8 @@ static bool optimize_lexical_comparison (gfc_expr
 static void optimize_minmaxloc (gfc_expr **);
 static bool is_empty_string (gfc_expr *e);
 static void doloop_warn (gfc_namespace *);
+static void optimize_reduction (gfc_namespace *);
+static int callback_reduction (gfc_expr **, int *, void *);
 
 /* How deep we are inside an argument list.  */
 
@@ -107,6 +109,7 @@ gfc_run_passes (gfc_namespace *ns)
       expr_array = XNEWVEC(gfc_expr **, expr_size);
 
       optimize_namespace (ns);
+      optimize_reduction (ns);
       if (gfc_option.dump_fortran_optimized)
 	gfc_dump_parse_tree (ns, stdout);
 
@@ -180,7 +183,172 @@ optimize_expr (gfc_expr **e, int *walk_subtrees AT
   return 0;
 }
 
+/* Auxiliary function to handle the arguments to reduction intrnisics.
+   If the function is a scalar, just copy it; otherwise Returns the new
+   element, the old one can be freed.  */
 
+static gfc_expr *
+copy_walk_reduction_arg (gfc_expr *e, gfc_expr *fn)
+{
+  gfc_expr *fcn;
+  const char *new_name;
+  gfc_actual_arglist *actual_arglist;
+
+  if (e->rank == 0 || e->expr_type == EXPR_FUNCTION)
+    fcn = gfc_copy_expr (e);
+  else
+    {
+      fcn = gfc_get_expr ();
+      fcn->expr_type = EXPR_FUNCTION;
+      fcn->value.function.isym = fn->value.function.isym;
+      actual_arglist = gfc_get_actual_arglist ();
+      actual_arglist->expr = gfc_copy_expr (e);
+      actual_arglist->next = gfc_get_actual_arglist ();
+      fcn->value.function.actual = actual_arglist;
+      fcn->ts = fn->ts;
+
+      switch (fn->value.function.isym->id)
+	{
+	case GFC_ISYM_SUM:
+	  new_name = "__internal_sum";
+	  break;
+	  
+	case GFC_ISYM_PRODUCT:
+	  new_name = "__internal_product";
+	  break;
+	  
+	case GFC_ISYM_ANY:
+	  new_name = "__internal_any";
+	  break;
+
+	case GFC_ISYM_ALL:
+	  new_name = "__internal_all";
+	  break;
+
+	default:
+	  abort ();
+	}
+
+      gfc_get_sym_tree (new_name, current_ns, &fcn->symtree, false);
+      fcn->symtree->n.sym->attr.flavor = FL_PROCEDURE;
+      fcn->symtree->n.sym->attr.function = 1;
+      fcn->symtree->n.sym->attr.elemental = 1;
+      fcn->symtree->n.sym->attr.referenced = 1;
+      fcn->symtree->n.sym->attr.access = ACCESS_PRIVATE;
+      gfc_commit_symbol (fcn->symtree->n.sym);
+    }
+
+  (void) gfc_expr_walker (&fcn, callback_reduction, NULL);
+
+  return fcn;
+}
+
+/* Callback function for optimzation of reductions to scalars.  Transform
+   ANY ([f1,f2,f3, ...]) to f1 .or. f2 .or. f3 .or. ..., with ANY,
+   SUM and PRODUCT correspondingly.  Handly only the simple cases without
+   MASK and DIM.  */
+
+static int
+callback_reduction (gfc_expr **e, int *walk_subtrees ATTRIBUTE_UNUSED,
+		    void *data ATTRIBUTE_UNUSED)
+{
+  gfc_expr *fn, *arg;
+  gfc_intrinsic_op op;
+  gfc_isym_id id;
+  gfc_actual_arglist *a;
+  gfc_actual_arglist *dim;
+  gfc_constructor *c;
+  gfc_expr *res, *new_expr;
+
+  fn = *e;
+
+  if (fn->rank != 0 || fn->expr_type != EXPR_FUNCTION
+      || fn->value.function.isym == NULL)
+    return 0;
+
+  id = fn->value.function.isym->id;
+
+  if (id != GFC_ISYM_SUM && id != GFC_ISYM_PRODUCT
+      && id != GFC_ISYM_ANY && id != GFC_ISYM_ALL)
+    return 0;
+
+  a = fn->value.function.actual;
+
+  /* Don't handle MASK or DIM.  */
+
+  dim = a->next;
+
+  if (dim != NULL)
+    {
+      gfc_actual_arglist *mask;
+
+      if (dim->expr != NULL)
+	return 0;
+      
+      mask = dim->next;
+      if (mask != NULL)
+	if ( mask->expr != NULL)
+	  return 0;
+    }
+
+  arg = a->expr;
+
+  if (arg->expr_type != EXPR_ARRAY)
+    return 0;
+
+  switch (id)
+    {
+    case GFC_ISYM_SUM:
+      op = INTRINSIC_PLUS;
+      break;
+
+    case GFC_ISYM_PRODUCT:
+      op = INTRINSIC_TIMES;
+      break;
+
+    case GFC_ISYM_ANY:
+      op = INTRINSIC_OR;
+      break;
+
+    case GFC_ISYM_ALL:
+      op = INTRINSIC_AND;
+      break;
+
+    default:
+      return 0;
+    }
+
+  c = gfc_constructor_first (arg->value.constructor);
+
+  if (c == NULL)
+    return 0;
+
+  res = copy_walk_reduction_arg (c->expr, fn);
+
+  c = gfc_constructor_next (c);
+  while (c)
+    {
+      new_expr = gfc_get_expr ();
+      new_expr->ts = fn->ts;
+      new_expr->expr_type = EXPR_OP;
+      new_expr->rank = fn->rank;
+      new_expr->where = fn->where;
+      new_expr->value.op.op = op;
+      new_expr->value.op.op1 = res;
+      new_expr->value.op.op2 = copy_walk_reduction_arg (c->expr, fn);
+      res = new_expr;
+      c = gfc_constructor_next (c);
+    }
+
+  gfc_simplify_expr (res, 0);
+  *e = res;
+  gfc_free_expr (fn);
+
+  /* We changed things from under the expression walker.  Walking the
+     old tree would mess up things, so let's not do that.  */
+  return 1;
+}
+
 /* Callback function for common function elimination, called from cfe_expr_0.
    Put all eligible function expressions into expr_array.  */
 
@@ -484,6 +652,16 @@ dummy_expr_callback (gfc_expr **e ATTRIBUTE_UNUSED
   return 0;
 }
 
+/* Dummy function for code callback, for use when we really
+   don't want to do anything.  */
+static int
+dummy_code_callback (gfc_code **e ATTRIBUTE_UNUSED,
+		     int *walk_subtrees ATTRIBUTE_UNUSED,
+		     void *data ATTRIBUTE_UNUSED)
+{
+  return 0;
+}
+
 /* Code callback function for converting
    do while(a)
    end do
@@ -639,6 +817,20 @@ optimize_namespace (gfc_namespace *ns)
     }
 }
 
+static void
+optimize_reduction (gfc_namespace *ns)
+{
+  current_ns = ns;
+  gfc_code_walker (&ns->code, dummy_code_callback, callback_reduction, NULL);
+
+/* BLOCKs are handled in the expression walker below.  */
+  for (ns = ns->contained; ns; ns = ns->sibling)
+    {
+      if (ns->code == NULL || ns->code->op != EXEC_BLOCK)
+	optimize_reduction (ns);
+    }
+}
+
 /* Replace code like
    a = matmul(b,c) + d
    with