[PATCH][alias-improvements] Some more VOP renaming tweaks

[Richard Guenther]

No need to do manual renaming in forwprop or DCE.  And we can avoid
automatic renaming on VDEF removal by propagating the associated VUSE
properly.

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

Richard.

2009-01-12  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-forwprop.c (tidy_after_forward_propagate_addr): Do
	not mark symbols for renaming.
	(forward_propagate_addr_expr): Match up push/pop_stmt_changes
	with the same statement, make sure to update the new pointed-to one.
	* tree-ssa-dce.c (eliminate_unnecessary_stmts): Do not copy
	call statements, do not mark symbols for renaming.
	* tree-ssa-operands.c (finalize_ssa_vdefs): Do not mark the VOP
	for renaming if a VDEF is removed but instead unlink that from
	the IL.

Index: gcc/tree-ssa-forwprop.c
===================================================================
*** gcc/tree-ssa-forwprop.c.orig	2009-01-12 11:59:23.000000000 +0100
--- gcc/tree-ssa-forwprop.c	2009-01-12 12:00:09.000000000 +0100
*************** tidy_after_forward_propagate_addr (gimpl
*** 586,593 ****
  
    if (TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
       recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
- 
-   mark_symbols_for_renaming (stmt);
  }
  
  /* DEF_RHS contains the address of the 0th element in an array.
--- 586,591 ----
*************** forward_propagate_addr_expr (tree name,
*** 884,901 ****
  	  continue;
  	}
  
-       push_stmt_changes (&use_stmt);
- 
        {
  	gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
  	result = forward_propagate_addr_expr_1 (name, rhs, &gsi,
  						single_use_p);
! 	use_stmt = gsi_stmt (gsi);
        }
        all &= result;
  
-       pop_stmt_changes (&use_stmt);
- 
        /* Remove intermediate now unused copy and conversion chains.  */
        use_rhs = gimple_assign_rhs1 (use_stmt);
        if (result
--- 882,905 ----
  	  continue;
  	}
  
        {
  	gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
+ 	push_stmt_changes (&use_stmt);
  	result = forward_propagate_addr_expr_1 (name, rhs, &gsi,
  						single_use_p);
! 	/* If the use has moved to a different statement adjust
! 	   the update machinery.  */
! 	if (use_stmt != gsi_stmt (gsi))
! 	  {
! 	    pop_stmt_changes (&use_stmt);
! 	    use_stmt = gsi_stmt (gsi);
! 	    update_stmt (use_stmt);
! 	  }
! 	else
! 	  pop_stmt_changes (&use_stmt);
        }
        all &= result;
  
        /* Remove intermediate now unused copy and conversion chains.  */
        use_rhs = gimple_assign_rhs1 (use_stmt);
        if (result
Index: gcc/tree-ssa-dce.c
===================================================================
*** gcc/tree-ssa-dce.c.orig	2009-01-12 11:59:23.000000000 +0100
--- gcc/tree-ssa-dce.c	2009-01-12 12:00:09.000000000 +0100
*************** eliminate_unnecessary_stmts (void)
*** 692,698 ****
  	      if (call)
  		{
  		  tree name;
- 		  gimple g;
  
  		  /* When LHS of var = call (); is dead, simplify it into
  		     call (); saving one operand.  */
--- 692,697 ----
*************** eliminate_unnecessary_stmts (void)
*** 709,719 ****
  			}
  		      
  		      push_stmt_changes (gsi_stmt_ptr (&gsi));
! 		      g = gimple_copy (stmt);
! 		      gimple_call_set_lhs (g, NULL_TREE);
! 		      gsi_replace (&gsi, g, false);
! 		      maybe_clean_or_replace_eh_stmt (stmt, g);
! 		      mark_symbols_for_renaming (g);
  		      pop_stmt_changes (gsi_stmt_ptr (&gsi));
  		      release_ssa_name (name);
  		    }
--- 708,715 ----
  			}
  		      
  		      push_stmt_changes (gsi_stmt_ptr (&gsi));
! 		      gimple_call_set_lhs (stmt, NULL_TREE);
! 		      maybe_clean_or_replace_eh_stmt (stmt, stmt);
  		      pop_stmt_changes (gsi_stmt_ptr (&gsi));
  		      release_ssa_name (name);
  		    }
Index: gcc/tree-ssa-operands.c
===================================================================
*** gcc/tree-ssa-operands.c.orig	2009-01-12 11:59:23.000000000 +0100
--- gcc/tree-ssa-operands.c	2009-01-12 12:00:17.000000000 +0100
*************** finalize_ssa_vdefs (gimple stmt)
*** 856,868 ****
    /* If there is anything in the old list, free it.  */
    if (old_ops)
      {
        for (ptr = old_ops; ptr; ptr = last)
          {
  	  last = ptr->next;
  	  delink_imm_use (VDEF_OP_PTR (ptr, 0));
  	  add_vop_to_freelist (ptr);
  	}
-       mark_sym_for_renaming (gimple_vop (cfun));
      }
  
    /* Now set STMT's operands.  */
--- 856,868 ----
    /* If there is anything in the old list, free it.  */
    if (old_ops)
      {
+       unlink_stmt_vdef (stmt);
        for (ptr = old_ops; ptr; ptr = last)
          {
  	  last = ptr->next;
  	  delink_imm_use (VDEF_OP_PTR (ptr, 0));
  	  add_vop_to_freelist (ptr);
  	}
      }
  
    /* Now set STMT's operands.  */