Re: Processing global static (or const) variables

[Ehren Metcalfe <ehren.m@gmail.com>]

(Apologies to Richard for sending this twice -- I forgot to cc the list)

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

I've had some difficulty walking the DECL_INITIAL from within a
separate pass but I've added this code to the execute function of
pass_ipa_function_and_variable_visibility which should be about as
close to pass_build_cgraph_edges as I can get. Also the
record_references callback in cgraphbuild.c exhibits the same
behavior.

I get the same results with 4.3.4 and a recent checkout.

Is there a way to disable the optimizing away of qualified variants?
This seems to be a bug, especially with regard to
record_references_in_initializer and record_references in
cgraphbuild.c

On Mon, Apr 5, 2010 at 10:20 AM, Richard Guenther
<richard.guenther@gmail.com> wrote:
> 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) {
>>  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.
>
> 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
>>
>