Re: whereis PLUGIN_REGISTER_GGC_CACHES? how to migrate it for GCC v6.x?

[Leslie Zhai <lesliezhai at llvm dot org dot cn>]

在 2017年07月10日 22:16, David Malcolm 写道:
> On Sat, 2017-07-08 at 15:50 +0800, Leslie Zhai wrote:
> > Hi GCC developers,
> >
> > There was
> >
> > PLUGIN_REGISTER_GGC_CACHES
> >
> > pseudo-events for register_callback in GCC v4.x, but how to migrate
> > it
> > for GCC v6.x? there is no  PLUGIN_REGISTER_GGC_CACHES deprecated log
> > in
> > ChangeLog-201X nor git log plugin.h... please give me some hint,
> > thanks
> > a lot!
> Trevor [CCed] removed it 2014-12-10 in r218558
> (eb06b2519a361b7784b1807115fcb3dea0226035) in the commit:
> "remove gengtype support for param_is use_param, if_marked and splay
> tree allocators"
>
> The patch was here:
>    https://gcc.gnu.org/ml/gcc-patches/2014-11/msg02965.html
>
> where he talks about plugin migration.
 Some plugins may need to add extra GGC root tables, e.g. to handle 
their own
 @code{GTY}-ed data. This can be done with the 
@code{PLUGIN_REGISTER_GGC_ROOTS}
 pseudo-event with a null callback and the extra root table (of type 
@code{struct
-ggc_root_tab*}) as @code{user_data}.  Plugins that want to use the
-@code{if_marked} hash table option can add the extra GGC cache tables 
generated
-by @code{gengtype} using the @code{PLUGIN_REGISTER_GGC_CACHES} 
pseudo-event with
-a null callback and the extra cache table (of type @code{struct 
ggc_cache_tab*})
-as @code{user_data}.  Running the @code{gengtype -p @var{source-dir}
-@var{file-list} @var{plugin*.c} ...} utility generates these extra root 
tables.
+ggc_root_tab*}) as @code{user_data}.  Running the
+ @code{gengtype -p @var{source-dir} @var{file-list} @var{plugin*.c} ...}
+utility generates these extra root tables.


After diff gcc-6.3.0/gcc/testsuite/gcc.dg/plugin and 
gcc-4.8.0/gcc/testsuite/gcc.dg/plugin
then migrate to GCC v6.x like this:


// Register our garbage collector roots.
#if GCC_MAJOR < 6
  register_callback(plugin_name, PLUGIN_REGISTER_GGC_CACHES, NULL,
#else
  register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, NULL,
#endif
                    const_cast<ggc_cache_tab *>(gt_ggc_rc__gt_cache_h));


and Trevor talks more about GTY((if_marked(XXX), param_is(XXX))) htab_t 
migrate to GTY((cache)) hash_table<MyHasher> such as:


#if (GCC_MAJOR < 6)
// FIXME: gengtype not support macro?
static GTY((if_marked("tree2int_marked_p"), param_is(struct tree2int)))
    htab_t intCache;
#else
struct intCacheHasher : ggc_cache_ptr_hash<tree2int> {
  static inline hashval_t hash(tree2int *t2i) {
    return tree_map_base_hash(&t2i->base);
}

  static inline bool equal(tree2int *a, tree2int *b) {
    return a->base.from == b->base.from;
}
};
static GTY((cache))
    hash_table<intCacheHasher> *intCache;
#endif


But I have no idea why gengtype does not support macro? 
https://gcc.gnu.org/ml/gcc/2017-07/msg00045.html it just ignored #if 
(GCC_MAJOR < 6) still parse GTY((if_marked(XXX), param_is(XXX))) htab_t 
but not GTY((cache)) hash_table<MyHasher>... please give me some hint, 
thanks a lot!

> Hope this is helpful
> Dave

--
Regards,
Leslie Zhai - a LLVM developer https://reviews.llvm.org/p/xiangzhai/