[PATCH] Fix PR34706, PR34683 -- use more precise types for fortran arrays

[Richard Guenther]

This improves the type accuracy of fortran array types as used for example
for the temporaries in the testcase in PR34683.  This allows the
middle-end to more precisely see what is accessed and thus it reduces the
number of VOPs generated which in turn improves compile-time of that
testcase (-O -fstrict-aliasing) from 120s to 80s.

Bootstrapped and tested on x86_64-unknown-linux-gnu, ok for mainline?

Thanks,
Richard.

2008-01-08  Richard Guenther  <rguenther@suse.de>

	PR fortran/34706
	PR tree-optimization/34683
	* trans-types.c (gfc_get_array_type_bounds): Use an array type
	with known size for accesses if that is known.

Index: fortran/trans-types.c
===================================================================
*** fortran/trans-types.c	(revision 131372)
--- fortran/trans-types.c	(working copy)
*************** gfc_get_array_type_bounds (tree etype, i
*** 1436,1442 ****
  			   enum gfc_array_kind akind)
  {
    char name[8 + GFC_RANK_DIGITS + GFC_MAX_SYMBOL_LEN];
!   tree fat_type, base_type, arraytype, lower, upper, stride, tmp;
    const char *typename;
    int n;
  
--- 1436,1442 ----
  			   enum gfc_array_kind akind)
  {
    char name[8 + GFC_RANK_DIGITS + GFC_MAX_SYMBOL_LEN];
!   tree fat_type, base_type, arraytype, lower, upper, stride, tmp, rtype;
    const char *typename;
    int n;
  
*************** gfc_get_array_type_bounds (tree etype, i
*** 1511,1520 ****
    /* TODO: known offsets for descriptors.  */
    GFC_TYPE_ARRAY_OFFSET (fat_type) = NULL_TREE;
  
!   /* 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;
  
--- 1511,1525 ----
    /* TODO: known offsets for descriptors.  */
    GFC_TYPE_ARRAY_OFFSET (fat_type) = NULL_TREE;
  
!   /* We define data as an array with the correct size if possible.
!      Much better than doing pointer arithmetic.  */
!   if (stride)
!     rtype = build_range_type (gfc_array_index_type, gfc_index_zero_node,
! 			      int_const_binop (MINUS_EXPR, stride,
! 					       integer_one_node, 0));
!   else
!     rtype = gfc_array_range_type;
!   arraytype = build_array_type (etype, rtype);
    arraytype = build_pointer_type (arraytype);
    GFC_TYPE_ARRAY_DATAPTR_TYPE (fat_type) = arraytype;