Re: add dbgcnt and opt-info support for devirtualization

[Richard Biener <richard dot guenther at gmail dot com>]

On Mon, May 19, 2014 at 5:24 PM, Xinliang David Li <davidxl@google.com> wrote:
> Sorry about it. Here is the patch.  There is one remaining case where
> cgraph_dump_file and dump_enable_p are checked separately --
> cgraph_dump_file is set up differently from 'dump_file'.

But there you check with an else if, so if you do -fdump-ipa-cgraph
then suddenly -fopt-info will stop reporting?  At least in the cgraphunit.c
part of the patch.

I'm ok with the rest of the patch.

Thanks,
Richard.

> David
>
>
>
> On Mon, May 19, 2014 at 2:21 AM, Richard Biener
> <richard.guenther@gmail.com> wrote:
>> On Fri, May 16, 2014 at 11:19 PM, Xinliang David Li <davidxl@google.com> wrote:
>>> Modified the patch according to yours and Richard's feedback. PTAL.
>>
>> ENOPATCH.
>>
>> Btw, I don't see any issue with leaking node order to opt-report.
>>
>> Richard.
>>
>>> thanks,
>>>
>>> David
>>>
>>> On Fri, May 16, 2014 at 9:03 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>>>>> Hi, debugging runtime bugs due to devirtualization can be hard for
>>>>> very large C++ programs with complicated class hierarchy. This patch
>>>>> adds the support to report this high level transformation via
>>>>> -fopt-info (not hidden inside dump file) and the ability the do binary
>>>>> search with cutoff.
>>>>>
>>>>> Ok for trunk after build and test?
>>>>
>>>> Seems resonable to me.
>>>>>
>>>>> thanks,
>>>>>
>>>>> David
>>>>
>>>>> Index: ChangeLog
>>>>> ===================================================================
>>>>> --- ChangeLog (revision 210479)
>>>>> +++ ChangeLog (working copy)
>>>>> @@ -1,3 +1,18 @@
>>>>> +2014-05-15  Xinliang David Li  <davidxl@google.com>
>>>>> +
>>>>> +     * cgraphunit.c (walk_polymorphic_call_targets): Add
>>>>> +     dbgcnt and fopt-info support.
>>>>> +     2014-05-15  Xinliang David Li  <davidxl@google.com>
>>>>> +
>>>>> +             * cgraphunit.c (walk_polymorphic_call_targets): Add
>>>>> +             dbgcnt and fopt-info support.
>>>>> +             * ipa-prop.c (ipa_make_edge_direct_to_target): Ditto.
>>>>> +             * ipa-devirt.c (ipa_devirt): Ditto.
>>>>> +             * ipa.c (walk_polymorphic_call_targets): Ditto.
>>>>> +             * gimple-fold.c (fold_gimple_assign): Ditto.
>>>>> +             (gimple_fold_call): Ditto.
>>>>> +             * dbgcnt.def: New counter.
>>>>> +
>>>>>  2014-05-15  Martin Jambor  <mjambor@suse.cz>
>>>>>
>>>>>       PR ipa/61085
>>>>> Index: ipa-prop.c
>>>>> ===================================================================
>>>>> --- ipa-prop.c        (revision 210479)
>>>>> +++ ipa-prop.c        (working copy)
>>>>> @@ -59,6 +59,7 @@ along with GCC; see the file COPYING3.
>>>>>  #include "ipa-utils.h"
>>>>>  #include "stringpool.h"
>>>>>  #include "tree-ssanames.h"
>>>>> +#include "dbgcnt.h"
>>>>>
>>>>>  /* Intermediate information about a parameter that is only useful during the
>>>>>     run of ipa_analyze_node and is not kept afterwards.  */
>>>>> @@ -2494,6 +2495,13 @@ ipa_make_edge_direct_to_target (struct c
>>>>>           fprintf (dump_file, "ipa-prop: Discovered direct call to non-function"
>>>>>                               " in %s/%i, making it unreachable.\n",
>>>>>                    ie->caller->name (), ie->caller->order);
>>>>> +          else if (dump_enabled_p ())
>>>>> +         {
>>>>> +           location_t loc = gimple_location (ie->call_stmt);
>>>>> +           dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, loc,
>>>>> +                            "Discovered direct call to non-function in %s, "
>>>>> +                            "making it unreachable\n", ie->caller->name ());
>>>>
>>>> Perhaps "turning it to __builtin_unreachable call" and similarly in the other cases
>>>> we introduce __builtin_unreachable? I think that could be easier for user to work
>>>> out.
>>>>
>>>> What king of problems in devirtualizatoin you are seeing?
>>>>
>>>>
>>>> Honza