[PATCH][mem-ref] Fix DSE with pointers

[Richard Guenther]

Bootstrapped and "tested" on x86_64-unknown-linux-gnu, applied to the
branch.

2008-03-09  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-dse.c (dse_possible_dead_store_p): Handle
	INDIRECT_MEM_REF.

Index: mem-ref/gcc/tree-ssa-dse.c
===================================================================
*** mem-ref.orig/gcc/tree-ssa-dse.c	2008-03-09 16:20:42.000000000 +0100
--- mem-ref/gcc/tree-ssa-dse.c	2008-03-09 16:24:43.000000000 +0100
*************** dse_possible_dead_store_p (tree stmt,
*** 325,335 ****
        if (TREE_CODE (temp) == GIMPLE_MODIFY_STMT)
  	{
  	  tree base1 = get_base_address (GIMPLE_STMT_OPERAND (stmt, 0));
! 	  tree base2 =  get_base_address (GIMPLE_STMT_OPERAND (temp, 0));
  
! 	  while (base1 && INDIRECT_REF_P (base1))
  	    base1 = TREE_OPERAND (base1, 0);
! 	  while (base2 && INDIRECT_REF_P (base2))
  	    base2 = TREE_OPERAND (base2, 0);
  
  	  if (base1 != base2)
--- 325,339 ----
        if (TREE_CODE (temp) == GIMPLE_MODIFY_STMT)
  	{
  	  tree base1 = get_base_address (GIMPLE_STMT_OPERAND (stmt, 0));
! 	  tree base2 = get_base_address (GIMPLE_STMT_OPERAND (temp, 0));
  
! 	  while (base1
! 		 && (INDIRECT_REF_P (base1)
! 		     || TREE_CODE (base1) == INDIRECT_MEM_REF))
  	    base1 = TREE_OPERAND (base1, 0);
! 	  while (base2
! 		 && (INDIRECT_REF_P (base2)
! 		     || TREE_CODE (base2) == INDIRECT_MEM_REF))
  	    base2 = TREE_OPERAND (base2, 0);
  
  	  if (base1 != base2)