Re: [tree-ssa] Fix (hopefully) x86_64 bootstrap failure

[Jan Hubicka <hubicka at ucw dot cz>]

> 
> Sigh.  Via a wonderful series of events we had an SSA_NAME on the freelist,
> but still referenced in the IL.  Not good.
> 
> This patch avoids the problem by not removing PHI nodes (and thus freeing
> SSA_NAMES) until such point as we can do a full CFG cleanup which
> will ensure that all references to dead/unused variables will be wiped
> out together.
> 
> This makes flow.i build with an x86_64 cross compiler and hopefully brings
> it back to bootstrapping status.
> 
> I've also bootstrapped and regression tested this on i686-pc-linux-gnu.
> 
> 	* tree-ssa-dom.c (optimize_stmt): Don't call cleanup_control_expr
> 	here.  Instead just note that we need to cleanup the cfg (which
> 	will DTRT).

Interesting :)
It would be nice to try update checkers for such a easilly verifiable
bits so they become more usefull (or anoying?).  Does the attached patch
look OK?  (connection to my testing machine broke for some reason, but
it got bootstrapped i686-pc-gnu-linux at least)

Honza

	* tree-cfg.c (verify_addr_expr): Rename to ....
	(verify_expr):  ... this one; check that no SSA names are on
	freelist.
	(verify_stmt, verify_stmts): Update calls of verify_addr_expr.
Index: tree-cfg.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Attic/tree-cfg.c,v
retrieving revision 1.1.4.230
diff -c -3 -p -r1.1.4.230 tree-cfg.c
*** tree-cfg.c	6 Dec 2003 12:31:27 -0000	1.1.4.230
--- tree-cfg.c	14 Dec 2003 11:47:52 -0000
*************** has_label_p (basic_block bb, tree label)
*** 2791,2799 ****
     properly noticed as such.  */
  
  static tree
! verify_addr_expr (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
! 		  void *data ATTRIBUTE_UNUSED)
  {
    if (TREE_CODE (*tp) == ADDR_EXPR)
      {
        tree x = TREE_OPERAND (*tp, 0);
--- 2791,2805 ----
     properly noticed as such.  */
  
  static tree
! verify_expr (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
! 	     void *data ATTRIBUTE_UNUSED)
  {
+   if (TREE_CODE (*tp) == SSA_NAME
+       && SSA_NAME_IN_FREE_LIST (*tp))
+     {
+       error ("SSA name in freelist still referred");
+       return *tp;
+     }
    if (TREE_CODE (*tp) == ADDR_EXPR)
      {
        tree x = TREE_OPERAND (*tp, 0);
*************** verify_addr_expr (tree *tp, int *walk_su
*** 2805,2811 ****
        if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
  	return NULL;
        if (!TREE_ADDRESSABLE (x))
!         return x;
      }
    return NULL;
  }
--- 2811,2820 ----
        if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
  	return NULL;
        if (!TREE_ADDRESSABLE (x))
! 	{
!           error ("Address taken, but ADDRESABLE bit not set");
!           return x;
! 	}
      }
    return NULL;
  }
*************** verify_stmt (tree stmt)
*** 2827,2836 ****
        debug_generic_stmt (stmt);
        return true;
      }
!   addr = walk_tree (&stmt, verify_addr_expr, NULL, NULL);
    if (addr)
      {
-       error ("Address taken, but ADDRESABLE bit not set");
        debug_generic_stmt (addr);
        return true;
      }
--- 2836,2844 ----
        debug_generic_stmt (stmt);
        return true;
      }
!   addr = walk_tree (&stmt, verify_expr, NULL, NULL);
    if (addr)
      {
        debug_generic_stmt (addr);
        return true;
      }
*************** verify_stmts (void)
*** 2915,2924 ****
  		  err |= true;
  		}
  
! 	      addr = walk_tree (&t, verify_addr_expr, NULL, NULL);
  	      if (addr)
  		{
- 		  error ("Address taken, but ADDRESABLE bit not set");
  		  debug_generic_stmt (addr);
  		  err |= true;
  		}
--- 2923,2931 ----
  		  err |= true;
  		}
  
! 	      addr = walk_tree (&t, verify_expr, NULL, NULL);
  	      if (addr)
  		{
  		  debug_generic_stmt (addr);
  		  err |= true;
  		}