Re: [PATCH 04/18] remove TREE_CHAIN from SSA_NAME nodes

[Richard Guenther <richard.guenther@gmail.com>]

On Fri, Mar 11, 2011 at 5:23 AM, Nathan Froyd <froydnj@codesourcery.com> wrote:
> This conversion is straightforward.  The tricky part is converting
> FREE_SSANAMES into a VEC to eliminate the only use of TREE_CHAIN on
> SSA_NAMEs.

Ok for 4.7.

Thanks,
Richard.

> -Nathan
>
> gcc/
>        * tree-flow.h (struct gimple_df): Make free_ssanames a VEC.
>        * tree-ssanames.c (fini_ssanames): VEC_free it.
>        (make_ssa_name_fn): Update for VECness of free_ssanames.
>        (release_ssa_name, release_dead_ssa_names): Likewise.
>        * tree.h (struct tree_ssa_name): Include typed_tree instead of
>        tree_common.
>        * tree.c (initialize_tree_contains_struct): Mark TS_SSA_NAME as
>        TS_TYPED instead of TS_COMMON.
>
> diff --git a/gcc/tree-flow.h b/gcc/tree-flow.h
> index 14c8827..6b48697 100644
> --- a/gcc/tree-flow.h
> +++ b/gcc/tree-flow.h
> @@ -61,7 +61,7 @@ struct GTY(()) gimple_df {
>   struct pointer_map_t * GTY((skip(""))) decls_to_pointers;
>
>   /* Free list of SSA_NAMEs.  */
> -  tree free_ssanames;
> +  VEC(tree,gc) *free_ssanames;
>
>   /* Hashtable holding definition for symbol.  If this field is not NULL, it
>      means that the first reference to this variable in the function is a
> diff --git a/gcc/tree-ssanames.c b/gcc/tree-ssanames.c
> index c76dba5..06cdbee 100644
> --- a/gcc/tree-ssanames.c
> +++ b/gcc/tree-ssanames.c
> @@ -96,7 +96,7 @@ void
>  fini_ssanames (void)
>  {
>   VEC_free (tree, gc, SSANAMES (cfun));
> -  FREE_SSANAMES (cfun) = NULL;
> +  VEC_free (tree, gc, FREE_SSANAMES (cfun));
>  }
>
>  /* Dump some simple statistics regarding the re-use of SSA_NAME nodes.  */
> @@ -124,10 +124,9 @@ make_ssa_name_fn (struct function *fn, tree var, gimple stmt)
>   gcc_assert (DECL_P (var));
>
>   /* If our free list has an element, then use it.  */
> -  if (FREE_SSANAMES (fn))
> +  if (!VEC_empty (tree, FREE_SSANAMES (fn)))
>     {
> -      t = FREE_SSANAMES (fn);
> -      FREE_SSANAMES (fn) = TREE_CHAIN (FREE_SSANAMES (fn));
> +      t = VEC_pop (tree, FREE_SSANAMES (fn));
>  #ifdef GATHER_STATISTICS
>       ssa_name_nodes_reused++;
>  #endif
> @@ -234,9 +233,8 @@ release_ssa_name (tree var)
>       /* Note this SSA_NAME is now in the first list.  */
>       SSA_NAME_IN_FREE_LIST (var) = 1;
>
> -      /* And finally link it into the free list.  */
> -      TREE_CHAIN (var) = FREE_SSANAMES (cfun);
> -      FREE_SSANAMES (cfun) = var;
> +      /* And finally put it on the free list.  */
> +      VEC_safe_push (tree, gc, FREE_SSANAMES (cfun), var);
>     }
>  }
>
> @@ -334,8 +332,8 @@ replace_ssa_name_symbol (tree ssa_name, tree sym)
>  static unsigned int
>  release_dead_ssa_names (void)
>  {
> -  tree t, next;
> -  int n = 0;
> +  tree t;
> +  int n = VEC_length (tree, FREE_SSANAMES (cfun));
>   referenced_var_iterator rvi;
>
>   /* Current defs point to various dead SSA names that in turn point to
> @@ -343,17 +341,7 @@ release_dead_ssa_names (void)
>   FOR_EACH_REFERENCED_VAR (cfun, t, rvi)
>     set_current_def (t, NULL);
>   /* Now release the freelist.  */
> -  for (t = FREE_SSANAMES (cfun); t; t = next)
> -    {
> -      next = TREE_CHAIN (t);
> -      /* Dangling pointers might make GGC to still see dead SSA names, so it is
> -        important to unlink the list and avoid GGC from seeing all subsequent
> -        SSA names.  In longer run we want to have all dangling pointers here
> -        removed (since they usually go through dead statements that consume
> -        considerable amounts of memory).  */
> -      TREE_CHAIN (t) = NULL_TREE;
> -      n++;
> -    }
> +  VEC_free (tree, gc, FREE_SSANAMES (cfun));
>   FREE_SSANAMES (cfun) = NULL;
>
>   statistics_counter_event (cfun, "SSA names released", n);
> diff --git a/gcc/tree.c b/gcc/tree.c
> index 7d73c74..072ff19 100644
> --- a/gcc/tree.c
> +++ b/gcc/tree.c
> @@ -376,6 +376,7 @@ initialize_tree_contains_struct (void)
>        case TS_VECTOR:
>        case TS_STRING:
>        case TS_COMPLEX:
> +       case TS_SSA_NAME:
>          MARK_TS_TYPED (code);
>          break;
>
> @@ -385,7 +386,6 @@ initialize_tree_contains_struct (void)
>        case TS_LIST:
>        case TS_VEC:
>        case TS_EXP:
> -       case TS_SSA_NAME:
>        case TS_BLOCK:
>        case TS_BINFO:
>        case TS_STATEMENT_LIST:
> diff --git a/gcc/tree.h b/gcc/tree.h
> index 11c2f83..80888bc 100644
> --- a/gcc/tree.h
> +++ b/gcc/tree.h
> @@ -1970,7 +1970,7 @@ typedef struct GTY(()) ssa_use_operand_d {
>  #define SSA_NAME_IMM_USE_NODE(NODE) SSA_NAME_CHECK (NODE)->ssa_name.imm_uses
>
>  struct GTY(()) tree_ssa_name {
> -  struct tree_common common;
> +  struct typed_tree typed;
>
>   /* _DECL wrapped by this SSA name.  */
>   tree var;
> --
> 1.7.0.4
>
>