[patch] Fix aliasing problem with fortran

[Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>]

Hello,

gfc_get_array_type_bounds constructs an arraytype, and each time it does
so, it builds a new range type.  The range types produced here are not
shared, and in turn the array type built here is different each time
and gets a different aliasing class.  However, the code produced by the
frontend sometimes after inlining contains

int tmp[0:];
int (*b)[0:];

b = &tmp;

where the types of tmp and *b are different, but fields of tmp are accessed
both through tmp and through *b.  Such accesses are then (at RTL level)
supposed not to alias, thus causing a misscompilation in scheduling.

I don't have a testcase for clean branch, one of the testcases in the
testsuite fails for me in this way with some patches I am working on
applied.

Bootstrapped & regtested on i686.

Zdenek

	* trans-types.c (gfc_array_range_type): New variable.
	(gfc_init_types): Initialize gfc_array_range_type.
	(gfc_get_array_type_bounds): Use gfc_array_range_type.

Index: fortran/trans-types.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/fortran/trans-types.c,v
retrieving revision 1.43
diff -c -3 -p -r1.43 trans-types.c
*** fortran/trans-types.c	12 May 2005 18:19:37 -0000	1.43
--- fortran/trans-types.c	16 May 2005 14:04:20 -0000
*************** Software Foundation, 59 Temple Place - S
*** 50,55 ****
--- 50,56 ----
  static tree gfc_get_derived_type (gfc_symbol * derived);
  
  tree gfc_array_index_type;
+ tree gfc_array_range_type;
  tree pvoid_type_node;
  tree ppvoid_type_node;
  tree pchar_type_node;
*************** gfc_init_types (void)
*** 528,533 ****
--- 529,538 ----
    pchar_type_node = build_pointer_type (gfc_character1_type_node);
  
    gfc_array_index_type = gfc_get_int_type (gfc_index_integer_kind);
+   gfc_array_range_type
+ 	  = build_range_type (gfc_array_index_type,
+ 			      build_int_cst (gfc_array_index_type, 0),
+ 			      NULL_TREE);
  
    /* The maximum array element size that can be handled is determined
       by the number of bits available to store this field in the array
*************** gfc_get_array_type_bounds (tree etype, i
*** 1182,1190 ****
    /* We define data as an unknown size array. Much better than doing
       pointer arithmetic.  */
    arraytype =
!     build_array_type (etype,
! 		      build_range_type (gfc_array_index_type,
! 					gfc_index_zero_node, NULL_TREE));
    arraytype = build_pointer_type (arraytype);
    GFC_TYPE_ARRAY_DATAPTR_TYPE (fat_type) = arraytype;
  
--- 1187,1193 ----
    /* We define data as an unknown size array. Much better than doing
       pointer arithmetic.  */
    arraytype =
!     build_array_type (etype, gfc_array_range_type);
    arraytype = build_pointer_type (arraytype);
    GFC_TYPE_ARRAY_DATAPTR_TYPE (fat_type) = arraytype;