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Subject: Re: Processing global static (or const) variables
From: Richard Guenther <richard.guenther@gmail.com>
To: Ehren Metcalfe <ehren.m@gmail.com>
Cc: gcc@gcc.gnu.org, tglek@mozilla.com, jason@redhat.com
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On Mon, Apr 5, 2010 at 3:50 PM, Ehren Metcalfe <ehren.m@gmail.com> wrote:
> 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)=
 {
> =A0tree t =3D *tp;
>
> =A0if (TREE_CODE(t) =3D=3D FUNCTION_DECL) {
> =A0 =A0// dump function
> =A0}
>
> =A0return NULL_TREE;
> }
>
> static void find_funcs(tree decl) {
> =A0walk_tree(&decl, find_funcs_callback, NULL, NULL);
> }
>
> // elsewhere
> struct varpool_node *vnode;
> FOR_EACH_STATIC_VARIABLE(vnode)
> =A0find_funcs(DECL_INITIAL(vnode->decl));
>
> -----
>
> Unfortunately this doesn't work for code like this:
>
> -----
>
> int foo() {
> =A0return 0;
> }
>
> typedef struct {
> =A0int (*p) ();
> } Table;
>
> const /* or static, or const static */ Table t[] =3D {
> =A0{ 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.

At which point during the compilation does it not work?  I suppose
at the point where the qualified variants are already optimized away.

Richard.

> Thanks,
>
> Ehren
>