where to insert a new Simple IPA [measuring] pass from a plugin ?

where to insert a new Simple IPA [measuring] pass from a plugin ?

[Basile Starynkevitch]

Hello,

I want to insert, thru a plugin, a new IPA pass which won't change any 
internal representation but will just count Gimples and functions at the IPA level.

(for what it is worth, the plugin is MELT http://gcc-melt.org/
and the IPA pass is coded in MELT; but  we can safely pretend 
all this is C++ code - which in fact it is, 
since MELT generates C++ code).


BTW, -fdump-passes show me notably:


   tree-cfg                                            :  ON
   *warn_function_return                               :  ON
   tree-ompexp                                         :  OFF
   *build_cgraph_edges                                 :  ON
   *free_lang_data                                     :  ON
   ipa-visibility                                      :  ON
   ipa-early_local_cleanups                            :  ON

I have some issues finding the right place for such a pass. I was thinking of passing 
as the reference_pass_name of some struct register_pass_info either the "ipa-visibility" string or the "visibility" string, but somehow that does not work.


It is a pity that, AFAIK, a plugin cannot insert its pass in front of 
the all_small_ipa_passes (the variable inside passes.c) - or of the 
all_regular_ipa_passes; it would be 
nice if we had some plugin API for such things. What do you think?

BTW, I also have a suggestion. We have some (relatively new) code 
(perhaps from 4.8) which suggest names in error messages when an 
identifier is misspelled.. 

Can't we use the same code (or at least same algorithm) to suggest 
a pass name when given a mispelled pass name from a plugin?


In general, I find that we are a bit lacking documentation about where 
and how a plugin can insert its own passes.

Regards.

PS. See also http://gcc.gnu.org/ml/gcc/2010-11/msg00638.html
-- 
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359
8, rue de la Faiencerie, 92340 Bourg La Reine, France
*** opinions {are only mines, sont seulement les miennes} ***

Re: where to insert a new Simple IPA [measuring] pass from a plugin ?

[David Malcolm]

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On Mon, 2013-09-30 at 15:49 +0200, Basile Starynkevitch wrote:
> Hello,
> 
> I want to insert, thru a plugin, a new IPA pass which won't change any 
> internal representation but will just count Gimples and functions at the IPA level.
> 
> (for what it is worth, the plugin is MELT http://gcc-melt.org/
> and the IPA pass is coded in MELT; but  we can safely pretend 
> all this is C++ code - which in fact it is, 
> since MELT generates C++ code).
> 
> 
> BTW, -fdump-passes show me notably:
> 
> 
>    tree-cfg                                            :  ON
>    *warn_function_return                               :  ON
>    tree-ompexp                                         :  OFF
>    *build_cgraph_edges                                 :  ON
>    *free_lang_data                                     :  ON
>    ipa-visibility                                      :  ON
>    ipa-early_local_cleanups                            :  ON
> 
> I have some issues finding the right place for such a pass. I was thinking of passing 
> as the reference_pass_name of some struct register_pass_info either the "ipa-visibility" string or the "visibility" string, but somehow that does not work.
> 
> It is a pity that, AFAIK, a plugin cannot insert its pass in front of 
> the all_small_ipa_passes (the variable inside passes.c) - or of the 
> all_regular_ipa_passes; it would be 
> nice if we had some plugin API for such things. What do you think?

I had a go at implementing this using the python plugin, and I was
successful:  it worked for me (with gcc 4.7.2 fwiw) as a
SIMPLE_IPA_PASS, registering before "*free_lang_data", or as an
IPA_PASS, registering before "whole-program".

I'm attaching the script I wrote, though obviously it will need
translating from Python to MELT.  Hope this is helpful.

Here's the output: it's tallying the kinds of gimple statements since,
by function, within "demo.c":

$ LD_LIBRARY_PATH=gcc-c-api ./gcc-with-python show-stats.py demo.c -I/usr/include/python2.7 -c
make_a_list_of_random_ints_badly: [(<type 'gcc.GimpleAssign'>, 6), (<type 'gcc.GimpleCall'>, 5), (<type 'gcc.GimpleCond'>, 2), (<type 'gcc.GimpleReturn'>, 1), (<type 'gcc.GimpleLabel'>, 1)]
buggy_converter: [(<type 'gcc.GimpleAssign'>, 6), (<type 'gcc.GimpleCall'>, 1), (<type 'gcc.GimpleCond'>, 1), (<type 'gcc.GimpleReturn'>, 1), (<type 'gcc.GimpleLabel'>, 1)]
kwargs_example: [(<type 'gcc.GimpleAssign'>, 10), (<type 'gcc.GimpleCall'>, 1), (<type 'gcc.GimpleCond'>, 1), (<type 'gcc.GimpleReturn'>, 1), (<type 'gcc.GimpleLabel'>, 1)]
too_many_varargs: [(<type 'gcc.GimpleAssign'>, 7), (<type 'gcc.GimpleCall'>, 1), (<type 'gcc.GimpleCond'>, 1), (<type 'gcc.GimpleReturn'>, 1), (<type 'gcc.GimpleLabel'>, 1)]
not_enough_varargs: [(<type 'gcc.GimpleAssign'>, 5), (<type 'gcc.GimpleCall'>, 1), (<type 'gcc.GimpleCond'>, 1), (<type 'gcc.GimpleReturn'>, 1), (<type 'gcc.GimpleLabel'>, 1)]
socket_htons: [(<type 'gcc.GimpleAssign'>, 7), (<type 'gcc.GimpleCall'>, 3), (<type 'gcc.GimpleCond'>, 1), (<type 'gcc.GimpleReturn'>, 1), (<type 'gcc.GimpleLabel'>, 1)]



> BTW, I also have a suggestion. We have some (relatively new) code 
> (perhaps from 4.8) which suggest names in error messages when an 
> identifier is misspelled.. 
> 
> Can't we use the same code (or at least same algorithm) to suggest 
> a pass name when given a mispelled pass name from a plugin?
> 
> 
> In general, I find that we are a bit lacking documentation about where 
> and how a plugin can insert its own passes.

Agreed.   FWIW I find this map very helpful for this kind of thing:
https://gcc-python-plugin.readthedocs.org/en/latest/tables-of-passes.html
Perhaps it can somehow be integrated into GCC's own documentation.


> Regards.
> 
> PS. See also http://gcc.gnu.org/ml/gcc/2010-11/msg00638.html

Hope this is constructive
Dave

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from collections import Counter
import gcc

# We'll implement this as a custom pass, to be called directly before
# 'whole-program'
# See https://gcc-python-plugin.readthedocs.org/en/latest/tables-of-passes.html
# for a map showing how GCC's passes (actually for GCC 4.6)

class CountingPass(gcc.SimpleIpaPass):
    def execute(self):
        for node in gcc.get_callgraph_nodes():
            # Tally gimple statements by type:
            stmt_kinds = Counter()
            fun = node.decl.function
            if fun:
                for bb in fun.cfg.basic_blocks:
                    if bb.gimple:
                        for stmt in bb.gimple:
                            stmt_kinds[type(stmt)] += 1
                print('%s: %s' % (fun.decl.name, stmt_kinds.most_common(5)))

ps = CountingPass(name='counting-pass')
ps.register_before('*free_lang_data')

# This also works registering before "whole-program", but one has to change the
# base class to a gcc.IpaPass, rather than a gcc.SimpleIpaPass