diff mbox

Ensure count_scale is no larger than REG_BR_PROB_BASE

Message ID CAO2gOZVsnuEsNqJKMMj=cxbB4H6WB9o3j+twy=Ji2_poEz-Jow@mail.gmail.com
State New
Headers show

Commit Message

Dehao Chen May 19, 2014, 8:37 p.m. UTC
I've updated the patch. Shall I move the check inside cgraph_clone_node?

Thanks,
Dehao


On Fri, May 16, 2014 at 6:41 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> Do you mean adjusting bb->count? Because in
>> expand_call_inline(tree-inline.c), it will use bb->count to pass into
>> copy_body to calculate count_scale.
>
> What about taking here callee->count instead? For inline nodes without
> any capping hack, bb->count == edge->count = callee->count.
>
> When profile ends up being obviously inconsistent, I would say that
> inliner can cap callee->count during producing the clone...
>
> Honza
>>
>> Thanks,
>> Dehao
>>
>> On Fri, May 16, 2014 at 5:22 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> >> In AutoFDO, a basic block's count can be much larger than it's actual
>> >> count because debug info might be incorrect. In this case, a call edge
>> >> count (calculated from BB count) could be much larger than callee's
>> >> header count, making the count_scale incorrectly large.
>> >
>> > In this case I still think we should handle this when producing the clone:
>> > we do not want to have clone's count much larger as well, so i think inliner
>> > and ipa-cp needs to deal with capping here instead....
>> >
>> > Honza
>> >>
>> >> Dehao
>> >> >
>> >> >
>> >> > Honza

Comments

Jan Hubicka May 19, 2014, 8:40 p.m. UTC | #1
> I've updated the patch. Shall I move the check inside cgraph_clone_node?

Thanks,
I think it is OK as it is. I belive individual users should know what do to
in such cases themselves.
You may want to also check what ipa-cp is doing.

Patch is OK (with Changelog)
Honza
> 
> Thanks,
> Dehao
> 
> Index: gcc/ipa-inline-transform.c
> ===================================================================
> --- gcc/ipa-inline-transform.c (revision 210535)
> +++ gcc/ipa-inline-transform.c (working copy)
> @@ -183,8 +183,9 @@ clone_inlined_nodes (struct cgraph_edge *e, bool d
>    if (freq_scale == -1)
>      freq_scale = e->frequency;
>    n = cgraph_clone_node (e->callee, e->callee->decl,
> - e->count, freq_scale, update_original,
> - vNULL, true, inlining_into, NULL);
> + MIN (e->count, e->callee->count), freq_scale,
> + update_original, vNULL, true, inlining_into,
> + NULL);
>    cgraph_redirect_edge_callee (e, n);
>   }
>      }
> Index: gcc/tree-inline.c
> ===================================================================
> --- gcc/tree-inline.c (revision 210535)
> +++ gcc/tree-inline.c (working copy)
> @@ -4355,7 +4355,7 @@ expand_call_inline (basic_block bb, gimple stmt, c
>       function in any way before this point, as this CALL_EXPR may be
>       a self-referential call; if we're calling ourselves, we need to
>       duplicate our body before altering anything.  */
> -  copy_body (id, bb->count,
> +  copy_body (id, cg_edge->callee->count,
>         GCOV_COMPUTE_SCALE (cg_edge->frequency, CGRAPH_FREQ_BASE),
>       bb, return_block, NULL);
> 
> 
> On Fri, May 16, 2014 at 6:41 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
> >> Do you mean adjusting bb->count? Because in
> >> expand_call_inline(tree-inline.c), it will use bb->count to pass into
> >> copy_body to calculate count_scale.
> >
> > What about taking here callee->count instead? For inline nodes without
> > any capping hack, bb->count == edge->count = callee->count.
> >
> > When profile ends up being obviously inconsistent, I would say that
> > inliner can cap callee->count during producing the clone...
> >
> > Honza
> >>
> >> Thanks,
> >> Dehao
> >>
> >> On Fri, May 16, 2014 at 5:22 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
> >> >> In AutoFDO, a basic block's count can be much larger than it's actual
> >> >> count because debug info might be incorrect. In this case, a call edge
> >> >> count (calculated from BB count) could be much larger than callee's
> >> >> header count, making the count_scale incorrectly large.
> >> >
> >> > In this case I still think we should handle this when producing the clone:
> >> > we do not want to have clone's count much larger as well, so i think inliner
> >> > and ipa-cp needs to deal with capping here instead....
> >> >
> >> > Honza
> >> >>
> >> >> Dehao
> >> >> >
> >> >> >
> >> >> > Honza
Dehao Chen May 19, 2014, 9:15 p.m. UTC | #2
On Mon, May 19, 2014 at 1:40 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> I've updated the patch. Shall I move the check inside cgraph_clone_node?
>
> Thanks,
> I think it is OK as it is. I belive individual users should know what do to
> in such cases themselves.
> You may want to also check what ipa-cp is doing.

I checked ipa-cp, but didn't see count propagation anywhere. Could you
point me to the function?

Thanks,
Dehao

>
> Patch is OK (with Changelog)
> Honza
>>
>> Thanks,
>> Dehao
>>
>> Index: gcc/ipa-inline-transform.c
>> ===================================================================
>> --- gcc/ipa-inline-transform.c (revision 210535)
>> +++ gcc/ipa-inline-transform.c (working copy)
>> @@ -183,8 +183,9 @@ clone_inlined_nodes (struct cgraph_edge *e, bool d
>>    if (freq_scale == -1)
>>      freq_scale = e->frequency;
>>    n = cgraph_clone_node (e->callee, e->callee->decl,
>> - e->count, freq_scale, update_original,
>> - vNULL, true, inlining_into, NULL);
>> + MIN (e->count, e->callee->count), freq_scale,
>> + update_original, vNULL, true, inlining_into,
>> + NULL);
>>    cgraph_redirect_edge_callee (e, n);
>>   }
>>      }
>> Index: gcc/tree-inline.c
>> ===================================================================
>> --- gcc/tree-inline.c (revision 210535)
>> +++ gcc/tree-inline.c (working copy)
>> @@ -4355,7 +4355,7 @@ expand_call_inline (basic_block bb, gimple stmt, c
>>       function in any way before this point, as this CALL_EXPR may be
>>       a self-referential call; if we're calling ourselves, we need to
>>       duplicate our body before altering anything.  */
>> -  copy_body (id, bb->count,
>> +  copy_body (id, cg_edge->callee->count,
>>         GCOV_COMPUTE_SCALE (cg_edge->frequency, CGRAPH_FREQ_BASE),
>>       bb, return_block, NULL);
>>
>>
>> On Fri, May 16, 2014 at 6:41 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> >> Do you mean adjusting bb->count? Because in
>> >> expand_call_inline(tree-inline.c), it will use bb->count to pass into
>> >> copy_body to calculate count_scale.
>> >
>> > What about taking here callee->count instead? For inline nodes without
>> > any capping hack, bb->count == edge->count = callee->count.
>> >
>> > When profile ends up being obviously inconsistent, I would say that
>> > inliner can cap callee->count during producing the clone...
>> >
>> > Honza
>> >>
>> >> Thanks,
>> >> Dehao
>> >>
>> >> On Fri, May 16, 2014 at 5:22 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> >> >> In AutoFDO, a basic block's count can be much larger than it's actual
>> >> >> count because debug info might be incorrect. In this case, a call edge
>> >> >> count (calculated from BB count) could be much larger than callee's
>> >> >> header count, making the count_scale incorrectly large.
>> >> >
>> >> > In this case I still think we should handle this when producing the clone:
>> >> > we do not want to have clone's count much larger as well, so i think inliner
>> >> > and ipa-cp needs to deal with capping here instead....
>> >> >
>> >> > Honza
>> >> >>
>> >> >> Dehao
>> >> >> >
>> >> >> >
>> >> >> > Honza
Jan Hubicka May 19, 2014, 10:11 p.m. UTC | #3
> On Mon, May 19, 2014 at 1:40 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
> >> I've updated the patch. Shall I move the check inside cgraph_clone_node?
> >
> > Thanks,
> > I think it is OK as it is. I belive individual users should know what do to
> > in such cases themselves.
> > You may want to also check what ipa-cp is doing.
> 
> I checked ipa-cp, but didn't see count propagation anywhere. Could you
> point me to the function?

I believe it is done in update_specialized_profile and also via cgraph_create_virtual_clone

honza
diff mbox

Patch

Index: gcc/ipa-inline-transform.c
===================================================================
--- gcc/ipa-inline-transform.c (revision 210535)
+++ gcc/ipa-inline-transform.c (working copy)
@@ -183,8 +183,9 @@  clone_inlined_nodes (struct cgraph_edge *e, bool d
   if (freq_scale == -1)
     freq_scale = e->frequency;
   n = cgraph_clone_node (e->callee, e->callee->decl,
- e->count, freq_scale, update_original,
- vNULL, true, inlining_into, NULL);
+ MIN (e->count, e->callee->count), freq_scale,
+ update_original, vNULL, true, inlining_into,
+ NULL);
   cgraph_redirect_edge_callee (e, n);
  }
     }
Index: gcc/tree-inline.c
===================================================================
--- gcc/tree-inline.c (revision 210535)
+++ gcc/tree-inline.c (working copy)
@@ -4355,7 +4355,7 @@  expand_call_inline (basic_block bb, gimple stmt, c
      function in any way before this point, as this CALL_EXPR may be
      a self-referential call; if we're calling ourselves, we need to
      duplicate our body before altering anything.  */
-  copy_body (id, bb->count,
+  copy_body (id, cg_edge->callee->count,
        GCOV_COMPUTE_SCALE (cg_edge->frequency, CGRAPH_FREQ_BASE),
      bb, return_block, NULL);