[patch] for PR 19937

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

Hello,

in case original induction variable is used in exit condition,
we compare it with the unsigned final value.  This may be wrong
if the variable is signed.  This patch adds the necessary cast
of the final value.

The problem was uncovered by the patch to avoid producing iv increments
of form i = (int) ((unsigned) i + 1), probably due to one of the
optimizers no longer propagating the unsigned value to the comparison.

Bootstrapped & regtested on i686.

Zdenek

	PR tree-optimization/19937
	* tree-ssa-loop-ivopts.c (rewrite_use_compare): Cast the final value
	to the type of the induction variable.

Index: tree-ssa-loop-ivopts.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-ssa-loop-ivopts.c,v
retrieving revision 2.47
diff -c -3 -p -r2.47 tree-ssa-loop-ivopts.c
*** tree-ssa-loop-ivopts.c	10 Feb 2005 20:13:20 -0000	2.47
--- tree-ssa-loop-ivopts.c	13 Feb 2005 19:39:59 -0000
*************** rewrite_use_compare (struct ivopts_data 
*** 4877,4891 ****
    
    if (may_eliminate_iv (data, use, cand, &compare, &bound))
      {
        op = force_gimple_operand (unshare_expr (bound), &stmts,
  				 true, NULL_TREE);
  
        if (stmts)
  	bsi_insert_before (&bsi, stmts, BSI_SAME_STMT);
  
!       *use->op_p = build2 (compare, boolean_type_node,
! 			  var_at_stmt (data->current_loop,
! 				       cand, use->stmt), op);
        modify_stmt (use->stmt);
        return;
      }
--- 4877,4893 ----
    
    if (may_eliminate_iv (data, use, cand, &compare, &bound))
      {
+       tree var = var_at_stmt (data->current_loop, cand, use->stmt);
+       tree var_type = TREE_TYPE (var);
+ 
+       bound = fold_convert (var_type, bound);
        op = force_gimple_operand (unshare_expr (bound), &stmts,
  				 true, NULL_TREE);
  
        if (stmts)
  	bsi_insert_before (&bsi, stmts, BSI_SAME_STMT);
  
!       *use->op_p = build2 (compare, boolean_type_node, var, op);
        modify_stmt (use->stmt);
        return;
      }