Re: Where to find global var declaration

[Cristina Georgiana Opriceana <cristina dot opriceana at gmail dot com>]

On Wed, Apr 27, 2016 at 4:54 PM, David Malcolm <dmalcolm@redhat.com> wrote:
> On Wed, 2016-04-27 at 12:34 +0300, Cristina Georgiana Opriceana wrote:
>> Hello,
>>
>> I tried to add a new global declaration of a pointer and I expected
>> to
>> see it in varpool nodes, but it does not appear there.
>>
>> ustackptr = build_decl (UNKNOWN_LOCATION,
>>                              VAR_DECL, get_identifier ("ustackptr"),
>>                              build_pointer_type(void_type_node));
>> TREE_ADDRESSABLE (ustackptr) = 1;
>> TREE_USED (ustackptr) = 1;
>> rest_of_decl_compilation (ustackptr, 1, 0);
>>
>> and
>>
>> struct varpool_node *node;
>> FOR_EACH_VARIABLE (node) {
>>         fprintf(stdout, "%s\n", get_name(node->decl));
>> }
>
> FWIW, in the the jit "frontend", I wasn't aware of
> rest_of_decl_compilation. Instead I have the following code for
> creating a global variable, which calls varpool_node::get_create and
> varpool_node::finalize_decl directly on the VAR_DECL instance.
>
> That said, maybe rest_of_decl_compilation is the best approach, but I'm
> not sure why it isn't working for you.  (I'm not an expert at this, I
> copied from the C frontend and hacked it up till it worked).
>
> This is from gcc/jit/jit-playback.c (which has a family of wrapper classes around "tree", but hopefully the idea is clear):
>
> /* Construct a playback::lvalue instance (wrapping a tree).  */
>
> playback::lvalue *
> playback::context::
> new_global (location *loc,
>             enum gcc_jit_global_kind kind,
>             type *type,
>             const char *name)
> {
>   gcc_assert (type);
>   gcc_assert (name);
>   tree inner = build_decl (UNKNOWN_LOCATION, VAR_DECL,
>                            get_identifier (name),
>                            type->as_tree ());
>   TREE_PUBLIC (inner) = (kind != GCC_JIT_GLOBAL_INTERNAL);
>   DECL_COMMON (inner) = 1;
>   switch (kind)
>     {
>     default:
>       gcc_unreachable ();
>
>     case GCC_JIT_GLOBAL_EXPORTED:
>       TREE_STATIC (inner) = 1;
>       break;
>
>     case GCC_JIT_GLOBAL_INTERNAL:
>       TREE_STATIC (inner) = 1;
>       break;
>
>     case GCC_JIT_GLOBAL_IMPORTED:
>       DECL_EXTERNAL (inner) = 1;
>       break;
>     }
>
>   if (loc)
>     set_tree_location (inner, loc);
>
>   varpool_node::get_create (inner);
>
>   varpool_node::finalize_decl (inner);
>
>   m_globals.safe_push (inner);
>
>   return new lvalue (this, inner);
> }
>
>
> Hope this is helpful

I've checked the rest_of_decl_compilation for your steps and
apparently I missed to set the storage to be static. I thought it
would be automatically set on 1 for global vars.

Thanks!
Cristina

> Dave