On Fri, 26 Oct 2018, Jan Hubicka wrote:
> > On Fri, Oct 26, 2018 at 9:12 AM Jan Hubicka <hubi...@ucw.cz> wrote:
> > >
> > > Hi,
> > > this patch frees TYPE_DECL and alignment from TYPE_DECL and also preserves
> > > only those TYPE_DECL pointers that are actually used to build ODR type
> > > tree.
> > >
> > > It reduces number of TYPE_DECLs streamed from WPA to ltrans to about 20%
> > > and is important for the patch turning types to incomplete types. Without
> > > this change the TREE_TYPE of TYPE_DECL would still point back to complete
> > > type
> > > and duplicating TYPE_DECLs as well is somewhat laborious.
> >
> > So the following is the really important hunk, correct?
> >
> > > @@ -5174,7 +5174,7 @@ free_lang_data_in_type (tree type)
> > >
> > > /* Drop TYPE_DECLs in TYPE_NAME in favor of the identifier in the
> > > TYPE_DECL if the type doesn't have linkage. */
> > > - if (! type_with_linkage_p (type))
> > > + if (type != TYPE_MAIN_VARIANT (type) || ! type_with_linkage_p (type))
> > > {
> > > TYPE_NAME (type) = TYPE_IDENTIFIER (type);
> > > TYPE_STUB_DECL (type) = NULL;
> >
> > Can you explain why you "free" alignment of TYPE_DECLs? It's just some
> > bits... does the FE somehow re-use those for sth else? I wouldn't have
> > expected those to be set to anything meaningful.
>
> It is set to 1 for forward declarations and 8 for fully defined types.
> Once I start to turn complete types into incomplete they would not match
> becaue of this difference.
Bah ;)
> >
> > I'm not too comfortable with setting TREE_TYPE of a TYPE_DECL to NULL.
> > Can we instead use void_type_node? The tree-inline.c hunk should
> > probably test whether DECL_ORIGINAL_TYPE is non-null instead.
>
> void_type_node works too. I wanted to put in something that will make any
> code that relies on it to crash (so I am sure there is none).
>
> Does the following variant look OK?
> I am re-testing it.
Yes.
Thanks,
Richard.
> * tree.c (free_lang_data_in_decl): Clear alignment and TREE_TYPE
> of TYPE_DECL.
> Index: tree.c
> ===================================================================
> --- tree.c (revision 265522)
> +++ tree.c (working copy)
> @@ -5354,6 +5354,10 @@ free_lang_data_in_decl (tree decl)
> DECL_VISIBILITY_SPECIFIED (decl) = 0;
> DECL_INITIAL (decl) = NULL_TREE;
> DECL_ORIGINAL_TYPE (decl) = NULL_TREE;
> + /* Make sure that complete and incomplete types have same TYPE_DECL.
> + C++ produces different DECL_ALIGN for them. */
> + SET_DECL_ALIGN (decl, 0);
> + TREE_TYPE (decl) = void_type_node;
> }
> else if (TREE_CODE (decl) == FIELD_DECL)
> DECL_INITIAL (decl) = NULL_TREE;
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
