[patch, fortran, committed] Fix regression PR 48412

[Thomas Koenig <tkoenig@netcologne.de>]

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Hello world,

I have committed the attached patch to trunk as obvious after 
regression-testing. The problem was that the assignment statements had 
been added in the wrong order, which was fixed by reversing the order of 
the loops looking for common function calls in cfe_expr_0.

Many thanks to Joost for finding the bug in the first place and for 
reducing that far!

	Thomas

2011-04-04  Thomas Koenig  <tkoenig@gcc.gnu.org>

         PR fortran/48412
         * frontend-passes (cfe_expr_0):  Reverse the order of going
         through the loops.

2011-04-04  Thomas Koenig  <tkoenig@gcc.gnu.org>

         PR fortran/48412
         * function_optimize_4.f90:  New test.

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Index: frontend-passes.c
===================================================================
--- frontend-passes.c	(Revision 171913)
+++ frontend-passes.c	(Arbeitskopie)
@@ -295,16 +295,16 @@ cfe_expr_0 (gfc_expr **e, int *walk_subtrees,
 
   gfc_expr_walker (e, cfe_register_funcs, NULL);
 
-  /* Walk backwards through all the functions to make sure we
-     catch the leaf functions first.  */
-  for (i=expr_count-1; i>=1; i--)
+  /* Walk through all the functions.  */
+
+  for (i=1; i<expr_count; i++)
     {
       /* Skip if the function has been replaced by a variable already.  */
       if ((*(expr_array[i]))->expr_type == EXPR_VARIABLE)
 	continue;
 
       newvar = NULL;
-      for (j=i-1; j>=0; j--)
+      for (j=0; j<i; j++)
 	{
 	  if (gfc_dep_compare_functions(*(expr_array[i]),
 					*(expr_array[j]), true)	== 0)

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! { dg-do run }
! { dg-options "-O" }
! PR 48412 - function elimination got temporary varibles in the wrong order.
! Test case contributed by Joost VandeVondele.

INTEGER FUNCTION S1(m,ma,lx)
INTEGER :: m,ma,lx

IF (((m < 0).AND.(MODULO(ABS(ma-lx),2) == 1)).OR.&
    ((m > 0).AND.(MODULO(ABS(ma-lx),2) == 0))) THEN
   S1=1
ELSE
   S1=0
ENDIF

END FUNCTION

INTEGER :: s1
IF (S1(1,2,1).NE.0) CALL ABORT()
END