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

[Sharad Singhai]

Ping.

Thanks,
Sharad

On Thu, Jun 7, 2012 at 10:16 PM, 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,
>
> 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.
>
> 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