[patch, fortran] Fix PR 52893

[Thomas Koenig]

Hello world,

after some time with a defective computer, I am back online.

Here is a fix for PR 52893 (which I just submitted, I wanted to
set a new record between bug posting and patch submissin :-), a
wrong-code regression for trunk and 4.7. Regression-tested.

OK for both?

        Thomas

2012-04-06  Thomas Koenig  <tkoe...@gcc.gnu.org>

        PR fortran/52893
        * frontend-passes.c:  Keep track of wether we are in an implicit
        DO loop; do not do function elimination if we are.

2012-04-06  Thomas Koenig  <tkoe...@gcc.gnu.org>

        PR fortran/52893
        * gfortran.dg/function_optimize_11.f90:  New test.

Index: frontend-passes.c
===================================================================
--- frontend-passes.c	(Revision 186190)
+++ frontend-passes.c	(Arbeitskopie)
@@ -70,6 +70,10 @@ static int forall_level;
 
 static bool in_omp_workshare;
 
+/* Keep track of iterators for array constructors.  */
+
+static int iterator_level;
+
 /* Entry point - run all passes for a namespace.  So far, only an
    optimization pass is run.  */
 
@@ -179,6 +183,12 @@ cfe_register_funcs (gfc_expr **e, int *walk_subtre
   if (forall_level > 0)
     return 0;
 
+  /* Function elimination inside an iterator could lead to functions
+     which depend on iterator variables being moved outside.  */
+
+  if (iterator_level > 0)
+    return 0;
+
   /* If we don't know the shape at compile time, we create an allocatable
      temporary variable to hold the intermediate result, but only if
      allocation on assignment is active.  */
@@ -581,6 +591,7 @@ optimize_namespace (gfc_namespace *ns)
 
   current_ns = ns;
   forall_level = 0;
+  iterator_level = 0;
   in_omp_workshare = false;
 
   gfc_code_walker (&ns->code, convert_do_while, dummy_expr_callback, NULL);
@@ -1140,9 +1151,13 @@ gfc_expr_walker (gfc_expr **e, walk_expr_fn_t expr
 	    for (c = gfc_constructor_first ((*e)->value.constructor); c;
 		 c = gfc_constructor_next (c))
 	      {
-		WALK_SUBEXPR (c->expr);
-		if (c->iterator != NULL)
+		if (c->iterator == NULL)
+		  WALK_SUBEXPR (c->expr);
+		else
 		  {
+		    iterator_level ++;
+		    WALK_SUBEXPR (c->expr);
+		    iterator_level --;
 		    WALK_SUBEXPR (c->iterator->var);
 		    WALK_SUBEXPR (c->iterator->start);
 		    WALK_SUBEXPR (c->iterator->end);

! { dg-do run }
! { dg-options "-ffrontend-optimize" }
! Do not move common functions out of implicit DO loop constructors.
program test
  integer, parameter :: N = 4
  integer, parameter :: dp=kind(1.d0)
  real(kind=dp), parameter :: pi=4*atan(1._dp)
  real(kind=dp), parameter :: eps = 1.e-14_dp
  real(kind=dp) :: h1(0:N-1), h2(0:N-1)
  integer i

  i = 1
  h1 = [(cos(2*pi*mod(i*k,N)/N),k=0,N/2), &
       & (sin(2*pi*mod(i*k,N)/N),k=1,N/2-1)]
  h2 = (/ 1._dp, 0._dp, -1._dp, 1._dp /)
  if (any(abs(h1 - h2) > eps)) call abort
end program test