On 10/26/2015 02:48 PM, Richard Biener wrote:
> On Thu, Oct 22, 2015 at 1:02 PM, Martin Liška <mli...@suse.cz> wrote:
>> On 10/21/2015 04:06 PM, Richard Biener wrote:
>>> On Wed, Oct 21, 2015 at 1:24 PM, Martin Liška <mli...@suse.cz> wrote:
>>>> On 10/21/2015 11:59 AM, Richard Biener wrote:
>>>>> On Wed, Oct 21, 2015 at 11:19 AM, Martin Liška <mli...@suse.cz> wrote:
>>>>>> On 10/20/2015 03:39 PM, Richard Biener wrote:
>>>>>>> On Tue, Oct 20, 2015 at 3:00 PM, Martin Liška <mli...@suse.cz> 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?
Thanks,
Martin
>
>> I'm attaching v3.
>>
>> Thanks,
>> Martin
>>
>>>
>>> Otherwise looks good to me.
>>>
>>> Richard.
>>>
>>>
>>>> Martin
>>>>
>>>>>
>>>>>> Thanks,
>>>>>> Martin
>>>>>>
>>>>>>>
>>>>>>> Richard.
>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Martin
>>>>>>
>>>>
>>
>From 4d02a44cef73dbdced230b8b3a80183b9bcca264 Mon Sep 17 00:00:00 2001
From: marxin <mli...@suse.cz>
Date: Thu, 22 Oct 2015 12:46:16 +0200
Subject: [PATCH] Version 4.
---
gcc/function.c | 7 +++++++
gcc/hsa-gen.c | 3 +--
gcc/passes.c | 26 +++++++++++++++++++++++++-
gcc/tree-pass.h | 3 +++
4 files changed, 36 insertions(+), 3 deletions(-)
diff --git a/gcc/function.c b/gcc/function.c
index db5bc1c..6878e9d 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -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;
+ }
+
struct function *new_cfun = cfun_stack.pop ();
/* When in_dummy_function, we do have a cfun but current_function_decl is
NULL. We also allow pushing NULL cfun and subsequently changing
diff --git a/gcc/passes.c b/gcc/passes.c
index 8b3fb2f..87dd25f 100644
--- a/gcc/passes.c
+++ b/gcc/passes.c
@@ -2378,6 +2378,26 @@ execute_one_pass (opt_pass *pass)
current_pass = NULL;
+ if (todo_after & TODO_discard_function)
+ {
+ gcc_assert (cfun);
+ /* As cgraph_node::release_body expects release dominators info,
+ we have to release it. */
+ if (dom_info_available_p (CDI_DOMINATORS))
+ free_dominance_info (CDI_DOMINATORS);
+
+ 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 ();
+ }
+
/* Signal this is a suitable GC collection point. */
if (!((todo_after | pass->todo_flags_finish) & TODO_do_not_ggc_collect))
ggc_collect ();
@@ -2392,6 +2412,9 @@ execute_pass_list_1 (opt_pass *pass)
{
gcc_assert (pass->type == GIMPLE_PASS
|| pass->type == RTL_PASS);
+
+ if (current_function_decl == NULL)
+ return;
if (execute_one_pass (pass) && pass->sub)
execute_pass_list_1 (pass->sub);
@@ -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 ();
}
diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
index 7a5f476..2627df3 100644
--- a/gcc/tree-pass.h
+++ b/gcc/tree-pass.h
@@ -296,6 +296,9 @@ protected:
/* Rebuild the callgraph edges. */
#define TODO_rebuild_cgraph_edges (1 << 22)
+/* Release function body and stop pass manager. */
+#define TODO_discard_function (1 << 23)
+
/* Internally used in execute_function_todo(). */
#define TODO_update_ssa_any \
(TODO_update_ssa \
--
2.6.2
