On Tue, Oct 27, 2015 at 4:30 PM, Martin Liška <[email protected]> wrote:
> On 10/27/2015 03:49 PM, Richard Biener wrote:
>> On Tue, Oct 27, 2015 at 1:36 PM, Martin Liška <[email protected]> wrote:
>>> On 10/26/2015 02:48 PM, Richard Biener wrote:
>>>> On Thu, Oct 22, 2015 at 1:02 PM, Martin Liška <[email protected]> wrote:
>>>>> On 10/21/2015 04:06 PM, Richard Biener wrote:
>>>>>> On Wed, Oct 21, 2015 at 1:24 PM, Martin Liška <[email protected]> wrote:
>>>>>>> On 10/21/2015 11:59 AM, Richard Biener wrote:
>>>>>>>> On Wed, Oct 21, 2015 at 11:19 AM, Martin Liška <[email protected]> wrote:
>>>>>>>>> On 10/20/2015 03:39 PM, Richard Biener wrote:
>>>>>>>>>> On Tue, Oct 20, 2015 at 3:00 PM, Martin Liška <[email protected]> wrote:
>>>>>>>>>>> Hello.
>>>>>>>>>>>
>>>>>>>>>>> As part of upcoming merge of HSA branch, we would like to have
>>>>>>>>>>> possibility to terminate
>>>>>>>>>>> pass manager after execution of the HSA generation pass. The HSA
>>>>>>>>>>> back-end is implemented
>>>>>>>>>>> as a tree pass that directly emits HSAIL from gimple tree
>>>>>>>>>>> representation. The pass operates
>>>>>>>>>>> on clones created by HSA IPA pass and the pass manager should stop
>>>>>>>>>>> execution of further
>>>>>>>>>>> RTL passes.
>>>>>>>>>>>
>>>>>>>>>>> Suggested patch survives bootstrap and regression tests on
>>>>>>>>>>> x86_64-linux-pc.
>>>>>>>>>>>
>>>>>>>>>>> What do you think about it?
>>>>>>>>>>
>>>>>>>>>> Are you sure it works this way?
>>>>>>>>>>
>>>>>>>>>> Btw, you will miss executing of all the cleanup passes that will
>>>>>>>>>> eventually free memory
>>>>>>>>>> associated with the function. So I'd rather support a
>>>>>>>>>> TODO_discard_function which
>>>>>>>>>> should basically release the body from the cgraph.
>>>>>>>>>
>>>>>>>>> Hi.
>>>>>>>>>
>>>>>>>>> Agree with you that I should execute all TODOs, which can be easily
>>>>>>>>> done.
>>>>>>>>> However, if I just try to introduce the suggested TODO and handle it
>>>>>>>>> properly
>>>>>>>>> by calling cgraph_node::release_body, then for instance
>>>>>>>>> fn->gimple_df, fn->cfg are
>>>>>>>>> released and I hit ICEs on many places.
>>>>>>>>>
>>>>>>>>> Stopping the pass manager looks necessary, or do I miss something?
>>>>>>>>
>>>>>>>> "Stopping the pass manager" is necessary after TODO_discard_function,
>>>>>>>> yes.
>>>>>>>> But that may be simply done via a has_body () check then?
>>>>>>>
>>>>>>> Thanks, there's second version of the patch. I'm going to start
>>>>>>> regression tests.
>>>>>>
>>>>>> As release_body () will free cfun you should pop_cfun () before
>>>>>> calling it (and thus
>>>>>
>>>>> Well, release_function_body calls both push & pop, so I think calling pop
>>>>> before cgraph_node::release_body is not necessary.
>>>>
>>>> (ugh).
>>>>
>>>>> If tried to call pop_cfun before cgraph_node::release_body, I have cfun
>>>>> still
>>>>> pointing to the same (function *) (which is gcc_freed, but cfun != NULL).
>>>>
>>>> Hmm, I meant to call pop_cfun then after it (unless you want to fix the
>>>> above,
>>>> none of the freeing functions should techincally need 'cfun', just add
>>>> 'fn' parameters ...).
>>>>
>>>> I expected pop_cfun to eventually set cfun to NULL if it popped the
>>>> "last" cfun. Why
>>>> doesn't it do that?
>>>>
>>>>>> drop its modification). Also TODO_discard_functiuon should be only set
>>>>>> for
>>>>>> local passes thus you should probably add a gcc_assert (cfun).
>>>>>> I'd move its handling earlier, definitely before the ggc_collect,
>>>>>> eventually
>>>>>> before the pass_fini_dump_file () (do we want a last dump of the
>>>>>> function or not?).
>>>>>
>>>>> Fully agree, moved here.
>>>>>
>>>>>>
>>>>>> @@ -2397,6 +2410,10 @@ execute_pass_list_1 (opt_pass *pass)
>>>>>> {
>>>>>> gcc_assert (pass->type == GIMPLE_PASS
>>>>>> || pass->type == RTL_PASS);
>>>>>> +
>>>>>> +
>>>>>> + if (!gimple_has_body_p (current_function_decl))
>>>>>> + return;
>>>>>>
>>>>>> too much vertical space. With popping cfun before releasing the body
>>>>>> the check
>>>>>> might just become if (!cfun) and
>>>>>
>>>>> As mentioned above, as release body is symmetric (calling push & pop),
>>>>> the suggested
>>>>> guard will not work.
>>>>
>>>> I suggest to fix it. If it calls push/pop it should leave with the
>>>> original cfun, popping again
>>>> should make it NULL?
>>>>
>>>>>>
>>>>>> @@ -2409,7 +2426,7 @@ execute_pass_list (function *fn, opt_pass *pass)
>>>>>> {
>>>>>> push_cfun (fn);
>>>>>> execute_pass_list_1 (pass);
>>>>>> - if (fn->cfg)
>>>>>> + if (gimple_has_body_p (current_function_decl) && fn->cfg)
>>>>>> {
>>>>>> free_dominance_info (CDI_DOMINATORS);
>>>>>> free_dominance_info (CDI_POST_DOMINATORS);
>>>>>>
>>>>>> here you'd need to guard the pop_cfun call on cfun != NULL. IMHO it's
>>>>>> better
>>>>>> to not let cfun point to deallocated data.
>>>>>
>>>>> As I've read the code, since we gcc_free 'struct function', one can just
>>>>> rely on
>>>>> gimple_has_body_p (current_function_decl) as it correctly realizes that
>>>>> DECL_STRUCT_FUNCTION (current_function_decl) == NULL.
>>>>
>>>> I'm sure that with some GC checking ggc_free makes them #deadbeef or so:
>>>>
>>>> void
>>>> ggc_free (void *p)
>>>> {
>>>> ...
>>>> #ifdef ENABLE_GC_CHECKING
>>>> /* Poison the data, to indicate the data is garbage. */
>>>> VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (p, size));
>>>> memset (p, 0xa5, size);
>>>> #endif
>>>>
>>>> so I don't think that's a good thing to rely on ;)
>>>>
>>>> Richard.
>>>
>>> Hi Richi, fully agree that relying of 0xdeadbeaf is not good.
>>> I'm sending quite simple patch v4 where I enable popping up
>>> the stack to eventually set cfun = current_function_decl = NULL.
>>>
>>> Question of using push & pop in cgraph_node::release_body should
>>> be orthogonal as there are other places where the function is used.
>>>
>>> What do you think about the patch?
>>
>> @@ -4763,6 +4763,13 @@ push_cfun (struct function *new_cfun)
>> void
>> pop_cfun (void)
>> {
>> + if (cfun_stack.is_empty ())
>> + {
>> + set_cfun (NULL);
>> + current_function_decl = NULL_TREE;
>> + return;
>> + }
>> +
>>
>> I'd like to avoid this by...
>>
>> @@ -2405,11 +2428,12 @@ execute_pass_list (function *fn, opt_pass *pass)
>> {
>> push_cfun (fn);
>> execute_pass_list_1 (pass);
>> - if (fn->cfg)
>> + if (current_function_decl && fn->cfg)
>> {
>> free_dominance_info (CDI_DOMINATORS);
>> free_dominance_info (CDI_POST_DOMINATORS);
>> }
>> +
>> pop_cfun ();
>>
>> making this conditional on if (cfun). Btw, please check cfun against NULL,
>> not current_function_decl.
>
> Done.
>
>>
>> + if (dom_info_available_p (CDI_POST_DOMINATORS))
>> + free_dominance_info (CDI_POST_DOMINATORS);
>> +
>> + /* Pop function inserted in execute_pass_list. */
>> + pop_cfun ();
>> +
>> + cgraph_node::get (cfun->decl)->release_body ();
>> +
>> + /* Set cfun and current_function_decl to be NULL. */
>> + pop_cfun ();
>> + }
>>
>> this also looks weird. Because you pop_cfun and then access cfun and
>> then you pop cfun again? I'd say most clean would be
>>
>> + if (dom_info_available_p (CDI_POST_DOMINATORS))
>> + free_dominance_info (CDI_POST_DOMINATORS);
>> + tree fn = cfun->decl;
>> pop_cfun ();
>> cgraph_node::get (fn)->release_body ();
>> }
>>
>> or does the comment say that the current function is on the stack
>> twice somehow? How can that happen?
>
> You are right, your change applied.
>
> Sending V5. If OK, I'll create corresponding changelog entry
> and run regression tests.
You still have
@@ -4763,6 +4763,13 @@ push_cfun (struct function *new_cfun)
void
pop_cfun (void)
{
+ if (cfun_stack.is_empty ())
+ {
+ set_cfun (NULL);
+ current_function_decl = NULL_TREE;
+ return;
+ }
and popping of cfun twice in execute_one_pass.
Richard.
> Thanks,
> Martin
>
>>
>> Richard.
>>
>>
>>> Thanks,
>>> Martin
>>>
>>>>
>>>>> I'm attaching v3.
>>>>>
>>>>> Thanks,
>>>>> Martin
>>>>>
>>>>>>
>>>>>> Otherwise looks good to me.
>>>>>>
>>>>>> Richard.
>>>>>>
>>>>>>
>>>>>>> Martin
>>>>>>>
>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>> Martin
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Richard.
>>>>>>>>>>
>>>>>>>>>>> Thanks,
>>>>>>>>>>> Martin
>>>>>>>>>
>>>>>>>
>>>>>
>>>
>
