[PATCH] Add option for dumping to stderr (issue6190057)

[Sharad Singhai]

Apologies for the spam. Attempting to resend the patch after shrinking it.

I have updated the attached patch to use a new dump message
classification system for the vectorizer. It currently uses four
classes, viz, MSG_OPTIMIZED_LOCATIONS, MSG_UNOPTIMIZED_LOCATION,
MSG_MISSING_OPTIMIZATION, and MSG_NOTE. I have gone through the
vectorizer passes and have converted each call to fprintf (dump_file,
....) to a message classification matching in spirit. Most often, it
is MSG_OPTIMIZED_LOCATIONS, but occasionally others as well.

For example, the following

if (vect_print_dump_info (REPORT_DETAILS))
  {
    fprintf (vect_dump, "niters for prolog loop: ");
    print_generic_expr (vect_dump, iters, TDF_SLIM);
  }

gets converted to

if (dump_kind (MSG_OPTIMIZED_LOCATIONS))
  {
     dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, vect_location,
                      "niters for prolog loop: ");
     dump_generic_expr (MSG_OPTIMIZED_LOCATIONS, TDF_SLIM, iters);
  }

The asymmetry between the first printf and the second is due to the
fact that 'vect_print_dump_info (xxx)' prints the location as a
"side-effect". To preserve the original intent somewhat, I have
converted the first call within a dump sequence to a dump_printf_loc
(xxx) which prints the location while the subsequence calls within the
same conditional get converted to the corresponding plain variants.

I considered removing the support for alternate dump file, but ended
up preserving it instead since it is needed for setting the alternate
dump file to stderr for the case when -fopt-info is given but no dump
file is available.

The following invocation
g++ ... -ftree-vectorize -fopt-info=4

dumps *all* available information to stderr. Currently, the opt-info
level is common to all passes, i.e., a pass can't specify if wants a
different level of diagnostic info. This can be added as an
enhancement with a suitable syntax for selecting passes.

I haven't fixed up the documentation/tests but wanted to get some
feedback about the current state of patch before doing that.

Thanks,
Sharad

On Fri, Jun 15, 2012 at 1:18 AM, Richard Guenther
<richard.guenther@gmail.com> wrote:
> On Fri, Jun 15, 2012 at 7:47 AM, Sharad Singhai <singhai@google.com> wrote:
>> On Wed, Jun 13, 2012 at 4:48 AM, Richard Guenther
>> <richard.guenther@gmail.com> wrote:
>>> On Fri, Jun 8, 2012 at 7:16 AM, Sharad Singhai <singhai@google.com> wrote:
>>>> Okay, I have updated the attached patch so that the output from
>>>> -ftree-vectorizer-verbose is considered diagnostic information and is
>>>> always
>>>> sent to stderr. Other functionality remains unchanged. Here is some
>>>> more context about this patch.
>>>>
>>>> This patch improves the dump infrastructure and public interfaces so
>>>> that the existing private pass-specific dump stream is separated from
>>>> the diagnostic dump stream (typically stderr).  The optimization
>>>> passes can output information on the two streams independently.
>>>>
>>>> The newly defined interfaces are:
>>>>
>>>> Individual passes do not need to access the dump file directly. Thus Instead
>>>> of doing
>>>>
>>>>   if (dump_file && (flags & dump_flags))
>>>>      fprintf (dump_file, ...);
>>>>
>>>> they can do
>>>>
>>>>     dump_printf (flags, ...);
>>>>
>>>> If the current pass has FLAGS enabled then the information gets
>>>> printed into the dump file otherwise not.
>>>>
>>>> Similar to the dump_printf (), another function is defined, called
>>>>
>>>>        diag_printf (dump_flags, ...)
>>>>
>>>> This prints information only onto the diagnostic stream, typically
>>>> standard error. It is useful for separating pass-specific dump
>>>> information from
>>>> the diagnostic information.
>>>>
>>>> Currently, as a proof of concept, I have converted vectorizer passes
>>>> to use the new dump format. For this, I have considered
>>>> information printed in vect_dump file as diagnostic. Thus 'fprintf'
>>>> calls are changed to 'diag_printf'. Some other information printed to
>>>> dump_file is sent to the regular dump file via 'dump_printf ()'. It
>>>> helps to separate the two streams because they might serve different
>>>> purposes and might have different formatting requirements.
>>>>
>>>> For example, using the trunk compiler, the following invocation
>>>>
>>>> g++ -S v.cc -ftree-vectorize -fdump-tree-vect -ftree-vectorizer-verbose=2
>>>>
>>>> prints tree vectorizer dump into a file named 'v.cc.113t.vect'.
>>>> However, the verbose diagnostic output is silently
>>>> ignored. This is not desirable as the two types of dump should not interfere.
>>>>
>>>> After this patch, the vectorizer dump is available in 'v.cc.113t.vect'
>>>> as before, but the verbose vectorizer diagnostic is additionally
>>>> printed on stderr. Thus both types of dump information are output.
>>>>
>>>> An additional feature of this patch is that individual passes can
>>>> print dump information into command-line named files instead of auto
>>>> numbered filename. For example,
>>>
>>> I'd wish you'd leave out this part for a followup.
>>>
>>>>
>>>> g++ -S -O2 v.cc -ftree-vectorize -fdump-tree-vect=foo.vect
>>>>     -ftree-vectorizer-verbose=2
>>>>     -fdump-tree-pre=foo.pre
>>>>
>>>> This prints the tree vectorizer dump into 'foo.vect', PRE dump into
>>>> 'foo.pre', and the vectorizer verbose diagnostic dump onto stderr.
>>>>
>>>> Please take another look.
>>>
>>> --- tree-vect-loop-manip.c      (revision 188325)
>>> +++ tree-vect-loop-manip.c      (working copy)
>>> @@ -789,14 +789,11 @@ slpeel_make_loop_iterate_ntimes (struct loop *loop
>>>   gsi_remove (&loop_cond_gsi, true);
>>>
>>>   loop_loc = find_loop_location (loop);
>>> -  if (dump_file && (dump_flags & TDF_DETAILS))
>>> -    {
>>> -      if (loop_loc != UNKNOWN_LOC)
>>> -        fprintf (dump_file, "\nloop at %s:%d: ",
>>> +  if (loop_loc != UNKNOWN_LOC)
>>> +    dump_printf (TDF_DETAILS, "\nloop at %s:%d: ",
>>>                  LOC_FILE (loop_loc), LOC_LINE (loop_loc));
>>> -      print_gimple_stmt (dump_file, cond_stmt, 0, TDF_SLIM);
>>> -    }
>>> -
>>> +  if (dump_flags & TDF_DETAILS)
>>> +    dump_gimple_stmt (TDF_SLIM, cond_stmt, 0);
>>>   loop->nb_iterations = niters;
>>>
>>> I'm confused by this.  Why is this not simply
>>>
>>>  if (loop_loc != UNKNOWN_LOC)
>>>    dump_printf (dump_flags, "\nloop at %s:%d: ",
>>>                       LOC_FILE (loop_loc), LOC_LINE (loop_loc));
>>>  dump_gimple_stmt (dump_flags | TDF_SLIM, cond_stmt, 0);
>>>
>>> for example.  I notice that you maybe mis-understood the message classification
>>> I asked you to add (maybe I confused you by mentioning to eventually re-use
>>> the TDF_* flags).  I think you basically provided this message classification
>>> by adding two classes by providing both dump_gimple_stmt and diag_gimple_stmt.
>>> But still in the above you keep a dump_flags test _and_ you pass in
>>> (altered) dump_flags to the dump/diag_gimple_stmt routines.  Let me quote them:
>>>
>>> +void
>>> +dump_gimple_stmt (int flags, gimple gs, int spc)
>>> +{
>>> +  if (dump_file)
>>> +    print_gimple_stmt (dump_file, gs, spc, flags);
>>> +}
>>>
>>> +void
>>> +diag_gimple_stmt (int flags, gimple gs, int spc)
>>> +{
>>> +  if (alt_dump_file)
>>> +    print_gimple_stmt (alt_dump_file, gs, spc, flags);
>>> +}
>>>
>>> I'd say it should have been a single function:
>>>
>>> void
>>> dump_gimple_stmt (enum msg_classification, int additional_flags,
>>> gimple gs, int spc)
>>> {
>>>  if (msg_classification & go-to-dumpfile
>>>      && dump_file)
>>>    print_gimple_stmt (dump_file, gs, spc, dump_flags | additional_flags);
>>>  if (msg_classification & go-to-alt-dump-file
>>>      && alt_dump_file && (alt_dump_flags & msg_classification))
>>>    print_gimple_stmt (alt_dump_file, gs, spc, alt_dump_flags |
>>> additional_flags);
>>> }
>>
>> Yes,  I can make the single function work for both regular (dump_file)
>> and diagnostic (stderr for now) dump streams. In fact, my original
>> patch did just that. However, it duplicated output on *both* the
>> streams. For example,
>>
>> gcc -O2 -ftree-vectorize -fdump-tree-vect=foo.vect
>> -ftree-vectorizer-verbose=2 foo.c
>>
>> Since both streams are enabled in this case, a call to dump_printf ()
>> would duplicate the information to both files, i.e., the dump and
>> diagnostic will be intermixed. Is that intended? My first thought was
>> to keep them separated via dump_*() and diag_* () methods.
>
> No, I think that's intended.  The regular dump-files should contain
> everything, the secondary stream (eventually enabled by -fopt-info)
> should be a filtered regular dump-file.
>
> Thanks,
> Richard.
>
>> Thanks,
>> Sharad
>>
>>> where msg_classification would include things to suitably classify messages
>>> for -fopt-info, like MSG_MISSED_OPTIMIZATION, MSG_OPTIMIZED, MSG_NOTE.
>>>
>>> In another place we have
>>>
>>> @@ -1648,7 +1642,7 @@ vect_can_advance_ivs_p (loop_vec_info loop_vinfo)
>>>   /* Analyze phi functions of the loop header.  */
>>>
>>>   if (vect_print_dump_info (REPORT_DETAILS))
>>> -    fprintf (vect_dump, "vect_can_advance_ivs_p:");
>>> +    diag_printf (TDF_TREE, "vect_can_advance_ivs_p:");
>>>
>>> so why's that diag_printf and why TDF_TREE?  I suppose you made all
>>> dumps to vect_dump diag_* and all dumps to dump_file dump_*?  I
>>> think it should have been
>>>
>>>   dump_printf (REPORT_DETAILS, "vect_can_advance_ivs_p:");
>>>
>>> thus dump_printf only gets the msg-classification and the printf args
>>> (dump-flags
>>> are only meaningful when passed down to pretty-printers).  Thus
>>>
>>> @@ -1658,8 +1652,8 @@ vect_can_advance_ivs_p (loop_vec_info loop_vinfo)
>>>       phi = gsi_stmt (gsi);
>>>       if (vect_print_dump_info (REPORT_DETAILS))
>>>        {
>>> -          fprintf (vect_dump, "Analyze phi: ");
>>> -          print_gimple_stmt (vect_dump, phi, 0, TDF_SLIM);
>>> +          diag_printf (TDF_TREE, "Analyze phi: ");
>>> +          diag_gimple_stmt (TDF_SLIM, phi, 0);
>>>        }
>>>
>>> should be
>>>
>>>  dump_printf (REPORT_DETAILS, "Analyze phi: ");
>>>  dump_gimple_stmt (REPORT_DETAILS, TDF_SLIM, phi, 0);
>>>
>>> and the if (vect_print_dump_info (REPORT_DETAILS)) should be what
>>> the dump infrastructure provides and thus hidden.  Eventually we should
>>> have a dump_kind (msg-classification) so we can replace it with
>>>
>>>   if (dump_kind (REPORT_DETAILS))
>>>     {
>>>       dump_printf (REPORT_DETAILS, "Analyze phi: ");
>>>       dump_gimple_stmt (REPORT_DETAILS, TDF_SLIM, phi, 0);
>>>     }
>>>
>>> to reduce the runtime overhead when not diagnosing/dumping.
>>>
>>> @@ -2464,8 +2458,8 @@ vect_create_cond_for_alias_checks (loop_vec_info l
>>>     }
>>>
>>>   if (vect_print_dump_info (REPORT_VECTORIZED_LOCATIONS))
>>> -    fprintf (vect_dump, "created %u versioning for alias checks.\n",
>>> -             VEC_length (ddr_p, may_alias_ddrs));
>>> +    diag_printf (TDF_TREE, "created %u versioning for alias checks.\n",
>>> +                 VEC_length (ddr_p, may_alias_ddrs));
>>>  }
>>>
>>> so here we have a different msg-classification,
>>> REPORT_VECTORIZED_LOCATIONS.  As we eventually want a central
>>> -fopt-report=... we do not want to leave this implementation detail to
>>> individual passes but gather them in a central place.
>>>
>>> Thanks,
>>> Richard.
>>>
>>>> Thanks,
>>>> Sharad
>>>>
>>>>
>>>> On Thu, Jun 7, 2012 at 12:19 AM, Xinliang David Li <davidxl@google.com> wrote:
>>>>> On Wed, Jun 6, 2012 at 10:58 PM, Sharad Singhai <singhai@google.com> wrote:
>>>>>> Sorry about the delay. I have finally incorporated all the suggestions
>>>>>> and reorganized the dump infrastructure a bit. The attached patch
>>>>>> updates vectorizer passes so that instead of accessing global
>>>>>> dump_file directly, these passes call dump_printf (FLAG, format, ...).
>>>>>> The dump_printf can choose between two streams, one regular pass dump
>>>>>> file, and another optional command line provided file. Currently, it
>>>>>> doesn't discriminate and all the dump information goes to both the
>>>>>> streams.
>>>>>>
>>>>>> Thus, for example,
>>>>>>
>>>>>> g++ -O2 v.cc -ftree-vectorize -fdump-tree-vect=foo.v -ftree-vectorizer-verbose=3
>>>>>
>>>>> But the default form of dump option (-fdump-tree-vect) no longer
>>>>> interferes with -ftree-vectorize-verbose=xxx output right? (this is
>>>>> one of the main requirements). One dumped to the primary stream (named
>>>>> dump file) and the other to the stderr -- the default diagnostic (alt)
>>>>> stream.
>>>>>
>>>>> David
>>>>>
>>>>>>
>>>>>> will output the verbose vectorizer information in both *.vect file and
>>>>>> foo.v file. However, as I have converted only vectorizer passes so
>>>>>> far, there is additional information in *.vect file which is not
>>>>>> present in foo.v file. Once other passes are converted to use this
>>>>>> scheme, then these two dump files should have identical output.
>>>>>>
>>>>>> Also note that in this patch -fdump-xxx=yyy format does not override
>>>>>> any auto named dump files as in my earlier patches. Instead the dump
>>>>>> information is output to both places when a command line dump file
>>>>>> option is provided.
>>>>>>
>>>>>> To summarize:
>>>>>> - instead of using dump_begin () / dump_end (), the passes should use
>>>>>> dump_start ()/dump_finish (). These new variants do not return the
>>>>>> dump_file. However, they still set the global dump_file/dump_flags for
>>>>>> the benefit of other passes during the transition.
>>>>>> - instead of directly printing to the dump_file, as in
>>>>>> if (dump_file)
>>>>>>  fprintf (dump_file, ...);
>>>>>>
>>>>>> The passes should do
>>>>>>
>>>>>> dump_printf (dump_flag, ...);
>>>>>> This will output to dump file(s) only when dump_flag is enabled for a
>>>>>> given pass.
>>>>>>
>>>>>> I have bootstrapped and tested it on x86_64. Does it look okay?
>>>>>>
>>>>>> Thanks,
>>>>>> Sharad
>>>>>>
>>>>>>
>>>>>> On Mon, May 14, 2012 at 12:26 AM, Richard Guenther
>>>>>> <richard.guenther@gmail.com> wrote:
>>>>>>> On Sat, May 12, 2012 at 6:39 PM, Xinliang David Li <davidxl@google.com> wrote:
>>>>>>>> On Sat, May 12, 2012 at 9:26 AM, Gabriel Dos Reis
>>>>>>>> <gdr@integrable-solutions.net> wrote:
>>>>>>>>> On Sat, May 12, 2012 at 11:05 AM, Xinliang David Li <davidxl@google.com> wrote:
>>>>>>>>>
>>>>>>>>>> The downside is that the dump file format will look different from the
>>>>>>>>>> stderr output which is less than ideal.
>>>>>>>>>
>>>>>>>>> BTW, why do people want to use stderr for dumping internal IRs,
>>>>>>>>> as opposed to stdout or other files?  That does not sound right.
>>>>>>>>>
>>>>>>>>
>>>>>>>> I was talking about the transformation information difference. In
>>>>>>>> stderr (where diagnostics go to), we may have
>>>>>>>>
>>>>>>>> foo.c: in function 'foo':
>>>>>>>> foo.c:5:6: note: loop was vectorized
>>>>>>>>
>>>>>>>> but in dump file the format for the information may be different,
>>>>>>>> unless we want to duplicate the machinery in diagnostics.
>>>>>>>
>>>>>>> So?  What's the problem with that ("different" diagnostics)?
>>>>>>>
>>>>>>> Richard.
>>>>>>>
>>>>>>>> David
>>>>>>>>
>>>>>>>>> -- Gaby
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