Re: [PATCH] ICF: move readonly decision for variables to the right place

[Jan Hubicka <hubicka@ucw.cz>]

> diff --git a/gcc/ipa-icf.c b/gcc/ipa-icf.c
> index 864a5d0..5b1fcff 100644
> --- a/gcc/ipa-icf.c
> +++ b/gcc/ipa-icf.c
> @@ -1410,10 +1410,6 @@ sem_variable::parse (varpool_node *node, bitmap_obstack *stack)
>    if (node->alias)
>      return NULL;
>  
> -  bool readonly = TYPE_P (decl) ? TYPE_READONLY (decl) : TREE_READONLY (decl);
> -  if (!readonly)
> -    return NULL;
> -
>    bool can_handle = DECL_VIRTUAL_P (decl)
>  		    || flag_merge_constants >= 2
>  		    || (!TREE_ADDRESSABLE (decl) && !node->externally_visible);

Please also drop can_handle and DECL_EXTERNAL check here.

can_handle seems to test if address matters. We already verify it at merging time
and at a time we consider REF_ADDR references. This is enough.
Moreover TREE_ADDRESSABLE and externally_visible flags are subject to change in between
analysis and WPA time.

Instead of this punt if THIS_VOLATILE is true.

Instead of ctor_for_folding bellow use DECL_INITIAL (ctor_for_folding may return
you NULL if it thinks the var is not safe)

> @@ -1900,7 +1896,14 @@ sem_item_optimizer::filter_removed_items (void)
>  	  if (!flag_ipa_icf_variables)
>  	    remove_item (item);
>  	  else
> -	    filtered.safe_push (item);
> +	    {
> +	      /* Filter out non-readonly variables.  */
> +	      tree decl = item->decl;
> +	      if (TYPE_P (decl) ? TYPE_READONLY (decl) : TREE_READONLY (decl))

Just test TREE_READONLY (decl).

OK with these changes.
Honza