Re: [PATCH] Pass manager: add support for termination of pass list

[Martin LiÅka <mliska at suse dot cz>]

On 10/21/2015 11:59 AM, Richard Biener wrote:
> On Wed, Oct 21, 2015 at 11:19 AM, Martin LiÅka <mliska@suse.cz> wrote:
>> On 10/20/2015 03:39 PM, Richard Biener wrote:
>>> On Tue, Oct 20, 2015 at 3:00 PM, Martin LiÅka <mliska@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.

Martin

> 
>> Thanks,
>> Martin
>>
>>>
>>> Richard.
>>>
>>>> Thanks,
>>>> Martin
>>

>From 3c969ee1257f88d9efaf6a55cf37705b847fa7ed Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Wed, 21 Oct 2015 13:18:29 +0200
Subject: [PATCH] Pass manager: add support for termination of pass list

gcc/ChangeLog:

2015-10-21  Martin Liska  <mliska@suse.cz>

	* function.c (pop_cfun): Add new condition to checking assert.
	* passes.c (execute_one_pass): Handle TODO_discard_function.
	(execute_pass_list_1): Stop pass manager if a function
	has release body.
	(execute_pass_list): Free dominators info just for functions
	that have gimple body.
	* tree-pass.h (TODO_discard_function): Introduce new TODO.
---
 gcc/function.c  |  1 +
 gcc/passes.c    | 19 ++++++++++++++++++-
 gcc/tree-pass.h |  3 +++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/gcc/function.c b/gcc/function.c
index f774214..a829d71 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -4770,6 +4770,7 @@ pop_cfun (void)
      pop_cfun.  */
   gcc_checking_assert (in_dummy_function
 		       || !cfun
+		       || !gimple_has_body_p (current_function_decl)
 		       || current_function_decl == cfun->decl);
   set_cfun (new_cfun);
   current_function_decl = new_cfun ? new_cfun->decl : NULL_TREE;
diff --git a/gcc/passes.c b/gcc/passes.c
index 6ef6d2e..a4b2a68 100644
--- a/gcc/passes.c
+++ b/gcc/passes.c
@@ -2387,6 +2387,19 @@ execute_one_pass (opt_pass *pass)
   if (!((todo_after | pass->todo_flags_finish) & TODO_do_not_ggc_collect))
     ggc_collect ();
 
+  if (todo_after & TODO_discard_function)
+    {
+      /* 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);
+
+      cgraph_node::get (cfun->decl)->release_body ();
+    }
+
   return true;
 }
 
@@ -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;
       if (execute_one_pass (pass) && pass->sub)
         execute_pass_list_1 (pass->sub);
       pass = pass->next;
@@ -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);
diff --git a/gcc/tree-pass.h b/gcc/tree-pass.h
index c37e4b2..fd6d8ba 100644
--- a/gcc/tree-pass.h
+++ b/gcc/tree-pass.h
@@ -300,6 +300,9 @@ 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			\
-- 
2.6.0