[patch, fortran] Some more function elimination tweaks

[Thomas Koenig <tkoenig at netcologne dot de>]

Hello world,

the attached patch does the following:

- It removes the restriction on functions returning allocatables
  for elimination (unnecessary since the introduction of allocatable
  temporary variables)

- It allows character function elimination if the character length is
  a constant known at compile time

- It removes introducing temporary variables for the TRANSFER function;
  this is better be handled by the middle-end.

Regression-tested.

OK for trunk?

	Thomas

2011-05-18  Thomas Koenig  <tkoenig@gcc.gnu.org>

        * frontend-passes.c (cfe_register_funcs):  Also register
        character functions if their charlens are known and constant.
        Also register allocatable functions.

2011-05-18  Thomas Koenig  <tkoenig@gcc.gnu.org>

        * gfortran.dg/function_optimize_8.f90:  New test case.
Index: frontend-passes.c
===================================================================
--- frontend-passes.c	(Revision 173754)
+++ frontend-passes.c	(Arbeitskopie)
@@ -137,8 +137,7 @@ optimize_expr (gfc_expr **e, int *walk_subtrees AT
 
 
 /* Callback function for common function elimination, called from cfe_expr_0.
-   Put all eligible function expressions into expr_array.  We can't do
-   allocatable functions.  */
+   Put all eligible function expressions into expr_array.  */
 
 static int
 cfe_register_funcs (gfc_expr **e, int *walk_subtrees ATTRIBUTE_UNUSED,
@@ -148,8 +147,10 @@ cfe_register_funcs (gfc_expr **e, int *walk_subtre
   if ((*e)->expr_type != EXPR_FUNCTION)
     return 0;
 
-  /* We don't do character functions (yet).  */
-  if ((*e)->ts.type == BT_CHARACTER)
+  /* We don't do character functions with unknown charlens.  */
+  if ((*e)->ts.type == BT_CHARACTER 
+      && ((*e)->ts.u.cl == NULL || (*e)->ts.u.cl->length == NULL
+	  || (*e)->ts.u.cl->length->expr_type != EXPR_CONSTANT))
     return 0;
 
   /* If we don't know the shape at compile time, we create an allocatable
@@ -163,9 +164,6 @@ cfe_register_funcs (gfc_expr **e, int *walk_subtre
      is specified.  */
   if ((*e)->value.function.esym)
     {
-      if ((*e)->value.function.esym->attr.allocatable)
-	return 0;
-
       /* Don't create an array temporary for elemental functions.  */
       if ((*e)->value.function.esym->attr.elemental && (*e)->rank > 0)
 	return 0;
@@ -181,9 +179,10 @@ cfe_register_funcs (gfc_expr **e, int *walk_subtre
   if ((*e)->value.function.isym)
     {
       /* Conversions are handled on the fly by the middle end,
-	 transpose during trans-* stages.  */
+	 transpose during trans-* stages and TRANSFER by the middle end.  */
       if ((*e)->value.function.isym->id == GFC_ISYM_CONVERSION
-	  || (*e)->value.function.isym->id == GFC_ISYM_TRANSPOSE)
+	  || (*e)->value.function.isym->id == GFC_ISYM_TRANSPOSE
+	  || (*e)->value.function.isym->id == GFC_ISYM_TRANSFER)
 	return 0;
 
       /* Don't create an array temporary for elemental functions,

Attachment: function_optimize_8.f90
Description: Text document