[patch] Make DSE a good citizen, use SSA operand iterators

[Steven Bosscher <stevenb at suse dot de>]

[Sorry Jeff, Andrew - never fill CC: before To:  :-/ ]

Hi,

While working on a DSE problem I noticed that it is not using
the operand iterators.  The patch below fixes that.  Bootstrapped
on {i686,x86-64}-suse-linux-gnu, testing ongoing but the patch is
quite trivial.
OK for mainline after testing completes?

Gr.
Steven

	* tree-ssa-dse.c (fix_phi_uses): Use SSA operand iterators.
	(fix_stmt_v_may_defs): Likewise.

Index: tree-ssa-dse.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-ssa-dse.c,v
retrieving revision 2.13
diff -c -3 -p -r2.13 tree-ssa-dse.c
*** tree-ssa-dse.c	8 Jan 2005 18:31:35 -0000	2.13
--- tree-ssa-dse.c	13 Jan 2005 22:04:46 -0000
*************** need_imm_uses_for (tree var)
*** 130,153 ****
  static void
  fix_phi_uses (tree phi, tree stmt)
  {
!   stmt_ann_t ann = stmt_ann (stmt);
!   v_may_def_optype v_may_defs;
!   unsigned int i;
!   int j;
  
    get_stmt_operands (stmt);
-   v_may_defs = V_MAY_DEF_OPS (ann);
  
!   /* Walk each V_MAY_DEF in STMT.  */
!   for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs); i++)
      {
!       tree v_may_def = V_MAY_DEF_RESULT (v_may_defs, i);
  
        /* Find any uses in the PHI which match V_MAY_DEF and replace
  	 them with the appropriate V_MAY_DEF_OP.  */
!       for (j = 0; j < PHI_NUM_ARGS (phi); j++)
! 	if (v_may_def == PHI_ARG_DEF (phi, j))
! 	  SET_PHI_ARG_DEF (phi, j, V_MAY_DEF_OP (v_may_defs, i));
      }
  }
  
--- 130,152 ----
  static void
  fix_phi_uses (tree phi, tree stmt)
  {
!   use_operand_p use_p;
!   def_operand_p def_p;
!   ssa_op_iter iter;
!   int i;
  
    get_stmt_operands (stmt);
  
!   FOR_EACH_SSA_MAYDEF_OPERAND (def_p, use_p, stmt, iter)
      {
!       tree v_may_def = DEF_FROM_PTR (def_p);
!       tree v_may_use = USE_FROM_PTR (use_p);
  
        /* Find any uses in the PHI which match V_MAY_DEF and replace
  	 them with the appropriate V_MAY_DEF_OP.  */
!       for (i = 0; i < PHI_NUM_ARGS (phi); i++)
! 	if (v_may_def == PHI_ARG_DEF (phi, i))
! 	  SET_PHI_ARG_DEF (phi, i, v_may_use);
      }
  }
  
*************** fix_phi_uses (tree phi, tree stmt)
*** 157,192 ****
  static void
  fix_stmt_v_may_defs (tree stmt1, tree stmt2)
  {
!   stmt_ann_t ann1 = stmt_ann (stmt1);
!   stmt_ann_t ann2 = stmt_ann (stmt2);
!   v_may_def_optype v_may_defs1;
!   v_may_def_optype v_may_defs2;
!   unsigned int i, j;
  
    get_stmt_operands (stmt1);
    get_stmt_operands (stmt2);
-   v_may_defs1 = V_MAY_DEF_OPS (ann1);
-   v_may_defs2 = V_MAY_DEF_OPS (ann2);
  
    /* Walk each V_MAY_DEF_OP in stmt1.  */
!   for (i = 0; i < NUM_V_MAY_DEFS (v_may_defs1); i++)
      {
!       tree v_may_def1 = V_MAY_DEF_OP (v_may_defs1, i);
  
        /* Find the appropriate V_MAY_DEF_RESULT in STMT2.  */
!       for (j = 0; j < NUM_V_MAY_DEFS (v_may_defs2); j++)
  	{
! 	  if (v_may_def1 == V_MAY_DEF_RESULT (v_may_defs2, j))
  	    {
  	      /* Update.  */
! 	      SET_V_MAY_DEF_OP (v_may_defs1, i, V_MAY_DEF_OP (v_may_defs2, j));
  	      break;
  	    }
  	}
  
!       /* If we did not find a corresponding V_MAY_DEF_RESULT, then something
! 	 has gone terribly wrong.  */
!       gcc_assert (j != NUM_V_MAY_DEFS (v_may_defs2));
      }
  }
  
--- 156,191 ----
  static void
  fix_stmt_v_may_defs (tree stmt1, tree stmt2)
  {
!   bool found = false;
!   ssa_op_iter iter1;
!   ssa_op_iter iter2;
!   use_operand_p use1_p, use2_p;
!   def_operand_p def1_p, def2_p;
  
    get_stmt_operands (stmt1);
    get_stmt_operands (stmt2);
  
    /* Walk each V_MAY_DEF_OP in stmt1.  */
!   FOR_EACH_SSA_MAYDEF_OPERAND (def1_p, use1_p, stmt1, iter1)
      {
!       tree use = USE_FROM_PTR (use1_p);
  
        /* Find the appropriate V_MAY_DEF_RESULT in STMT2.  */
!       FOR_EACH_SSA_MAYDEF_OPERAND (def2_p, use2_p, stmt2, iter2)
  	{
! 	  tree def = DEF_FROM_PTR (def2_p);
! 	  if (use == def)
  	    {
  	      /* Update.  */
! 	      SET_USE (use1_p, USE_FROM_PTR (use2_p));
! 	      found = true;
  	      break;
  	    }
  	}
  
!       /* If we did not find a corresponding V_MAY_DEF_RESULT,
! 	 then something has gone terribly wrong.  */
!       gcc_assert (found);
      }
  }
  
*************** dse_optimize_stmt (struct dom_walk_data 
*** 270,276 ****
        tree use;
        tree skipped_phi;
  
- 
        /* If there are no uses then there is nothing left to do.  */
        if (num_uses == 0)
  	{
--- 269,274 ----