On Thu, May 04, 2017 at 05:54:47PM +0200, Richard Biener wrote: > >2017-05-04 Jakub Jelinek <ja...@redhat.com> > > > > * tree.c (next_type_uid): Change type to unsigned. > > (type_hash_canon): Decrement back next_type_uid if > > freeing a type node with the highest TYPE_UID. For INTEGER_TYPEs > > also ggc_free TYPE_MIN_VALUE, TYPE_MAX_VALUE and TYPE_CACHED_VALUES > > if possible. > > > >--- gcc/tree.c.jj 2017-05-03 16:55:39.688052581 +0200 > >+++ gcc/tree.c 2017-05-03 18:49:30.662185944 +0200 > >@@ -151,7 +151,7 @@ static const char * const tree_node_kind > > /* Unique id for next decl created. */ > > static GTY(()) int next_decl_uid; > > /* Unique id for next type created. */ > >-static GTY(()) int next_type_uid = 1; > >+static GTY(()) unsigned next_type_uid = 1; > > /* Unique id for next debug decl created. Use negative numbers, > > to catch erroneous uses. */ > > static GTY(()) int next_debug_decl_uid; > >@@ -7188,6 +7188,19 @@ type_hash_canon (unsigned int hashcode, > > { > > tree t1 = ((type_hash *) *loc)->type; > > gcc_assert (TYPE_MAIN_VARIANT (t1) == t1); > >+ if (TYPE_UID (type) + 1 == next_type_uid) > >+ --next_type_uid; > >+ if (TREE_CODE (type) == INTEGER_TYPE) > >+ { > >+ if (TYPE_MIN_VALUE (type) > >+ && TREE_TYPE (TYPE_MIN_VALUE (type)) == type) > >+ ggc_free (TYPE_MIN_VALUE (type)); > >+ if (TYPE_MAX_VALUE (type) > >+ && TREE_TYPE (TYPE_MAX_VALUE (type)) == type) > >+ ggc_free (TYPE_MAX_VALUE (type)); > >+ if (TYPE_CACHED_VALUES_P (type)) > >+ ggc_free (TYPE_CACHED_VALUES (type)); > >+ } > > free_node (type); > > Shouldn't free_node handle this? That said, is freeing min/max safe? The > constants are shared after all.
The next_type_uid handling, I think it is better in type_hash_canon, the only other user after all calls free_node in a loop, so it is highly unlikely it would do anything there. If you mean the INTEGER_TYPE handling, then yes, I guess it could be done in free_node too and can move it there. If it was without the && TREE_TYPE (TYPE_M*_VALUE (type)) == type extra checks, then it is certainly unsafe and breaks bootstrap even, e.g. build_range_type and other spots happily create INTEGER_TYPEs with min/max value that have some other type. But when the type of the INTEGER_CSTs is the type we are ggc_freeing, anything that would refer to those constants afterwards would be necessarily broken (as their TREE_TYPE would be ggc_freed, possibly reused for something completely unrelated). Thus I think it should be safe even in the LTO case and thus doable in free_node. Jakub