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Subject: Processing global static (or const) variables
From: Ehren Metcalfe <ehren.m@gmail.com>
To: gcc@gcc.gnu.org
Cc: tglek@mozilla.com, jason@redhat.com
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Hello,

I'm trying to develop a dead code finder using gcc and mozilla's
treehydra but I've hit a wall processing certain initializations of
global variables.

In order to mark a function declaration whenever its address is held
in a file scope variable/table/structure I use code like this:

-----

static tree find_funcs_callback(tree *tp, int *walk_subtrees, void *data) {
  tree t = *tp;

  if (TREE_CODE(t) == FUNCTION_DECL) {
    // dump function
  }

  return NULL_TREE;
}

static void find_funcs(tree decl) {
  walk_tree(&decl, find_funcs_callback, NULL, NULL);
}

// elsewhere
struct varpool_node *vnode;
FOR_EACH_STATIC_VARIABLE(vnode)
  find_funcs(DECL_INITIAL(vnode->decl));

-----

Unfortunately this doesn't work for code like this:

-----

int foo() {
  return 0;
}

typedef struct {
  int (*p) ();
} Table;

const /* or static, or const static */ Table t[] = {
  { foo }
};

-----

If I remove the qualifiers from my table the initialization is
detected. Is this a bug or is there some other way of recovering the
FUNCTION_DECL? It doesn't need to be modular, I just have to find a
way to dump the function.

Thanks,

Ehren