re PR fortran/52893 (Moving functions out of implied DO loops)

2012-04-07  Thomas Koenig  <tkoenig@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.

2012-04-07  Thomas Koenig  <tkoenig@gcc.gnu.org>

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

From-SVN: r186213

4 files changed, 46 insertions, 2 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 050f25e..2b9b03c 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,9 @@
+2012-04-07  Thomas Koenig  <tkoenig@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  <tkoenig@gcc.gnu.org>
 
 	PR fortran/52668
diff --git a/gcc/fortran/frontend-passes.c b/gcc/fortran/frontend-passes.c
index a86982f..b20dabb 100644
--- a/gcc/fortran/frontend-passes.c
+++ b/gcc/fortran/frontend-passes.c
@@ -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 +183,13 @@ cfe_register_funcs (gfc_expr **e, int *walk_subtrees ATTRIBUTE_UNUSED,
   if (forall_level > 0)
     return 0;
 
+  /* Function elimination inside an iterator could lead to functions which
+     depend on iterator variables being moved outside.  FIXME: We should check
+     if the functions do indeed depend on the iterator variable.  */
+
+  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 +592,7 @@ 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 +1152,13 @@ gfc_expr_walker (gfc_expr **e, walk_expr_fn_t exprfn, void *data)
 	    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);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3d67560..7743667 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-04-07  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/52893
+	* gfortran.dg/function_optimize_11.f90:  New test.
+
 2012-04-06  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR fortran/52668
diff --git a/gcc/testsuite/gfortran.dg/function_optimize_11.f90 b/gcc/testsuite/gfortran.dg/function_optimize_11.f90
new file mode 100644
index 0000000..2e4831b
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/function_optimize_11.f90
@@ -0,0 +1,17 @@
+! { 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