* Processing global static (or const) variables
@ 2010-04-05 13:50 Ehren Metcalfe
2010-04-05 14:20 ` Richard Guenther
0 siblings, 1 reply; 4+ messages in thread
From: Ehren Metcalfe @ 2010-04-05 13:50 UTC (permalink / raw)
To: gcc; +Cc: tglek, jason
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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Processing global static (or const) variables
2010-04-05 13:50 Processing global static (or const) variables Ehren Metcalfe
@ 2010-04-05 14:20 ` Richard Guenther
2010-04-06 3:50 ` Ehren Metcalfe
0 siblings, 1 reply; 4+ messages in thread
From: Richard Guenther @ 2010-04-05 14:20 UTC (permalink / raw)
To: Ehren Metcalfe; +Cc: gcc, tglek, jason
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
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Processing global static (or const) variables
2010-04-05 14:20 ` Richard Guenther
@ 2010-04-06 3:50 ` Ehren Metcalfe
2010-04-06 8:49 ` Richard Guenther
0 siblings, 1 reply; 4+ messages in thread
From: Ehren Metcalfe @ 2010-04-06 3:50 UTC (permalink / raw)
To: Richard Guenther; +Cc: gcc
(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
>>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Processing global static (or const) variables
2010-04-06 3:50 ` Ehren Metcalfe
@ 2010-04-06 8:49 ` Richard Guenther
0 siblings, 0 replies; 4+ messages in thread
From: Richard Guenther @ 2010-04-06 8:49 UTC (permalink / raw)
To: Ehren Metcalfe; +Cc: gcc
On Tue, Apr 6, 2010 at 5:50 AM, Ehren Metcalfe <ehren.m@gmail.com> wrote:
> (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.
It should work there.
> 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
>>>
>>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2010-04-05 13:50 Processing global static (or const) variables Ehren Metcalfe
2010-04-05 14:20 ` Richard Guenther
2010-04-06 3:50 ` Ehren Metcalfe
2010-04-06 8:49 ` Richard Guenther
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