On Wed, 2019-04-10 at 17:53 +0200, Basile Starynkevitch wrote: > Hello All, > > This is work done for the CHARIOT H2020 project (see > https://www.chariotproject.eu/ for more context) in relation with my > BISMON project (see http://github.com/bstarynk/bismon/ for more, and, > if > you want more context, read the draft report on > http://starynkevitch.net/Basile/bismon-chariot-doc.pdf but skip the > few > first pages for H2020 managers). > > I have to make a preliminary proof-of-concept that my BISMON project > could be useful, with some ad-hoc GCC 8.3 plugin, to compute a crude > approximation of the call stack of a tiny freestanding kernel (for > x86 > in 32 bits, so compiled with: gcc-8 -ffreestanding -m32 -O2 -Wall > -fstack-usage and my plugin). > > I am working right now on that hand-written GCC 8.3 plugin. It > inserts > two GCC passes, and both passes are only analyzing passes (they > don't > change a single bit of GIMPLE or RTL representations). > > The first pass, named chariot_callgraph, is (oversimplifying) > printing > the call graph (and I will improve later that pass to communicate > with > BISMON). It is a pass of kind GIMPLE_PASS successfully inserted > after > the reference_pass_name "sra" and it works well enough. > > The second pass, named chariot_framesize, is (oversimplifying) > expected > to run with the printing the call frame size (and I will improve > later > that pass to communicate with BISMON). > > I want to insert that second pass following this explanation (in a > comment of mine). > > /* the fun->su exists as soon as -fstack-usage is passed, but it > is > filled much later, by the RTL pass named "pro_and_epilogue" at > gcc-8.3.0/gcc/config/i386/i386.c:13930 in function > ix86_expand_prologue; that pass is > pass_data_thread_prologue_and_epilogue defined in > gcc/function.c > line 6553 ... */ > > > To insert that second pass, I tried many things and failed. I was > expecting that an rtl- prefix is needed for an RTL pass. My > plugin_init > contains > > > struct register_pass_info my_framesize_pass_info; > my_framesize_pass_info.pass = make_pass_chariot_framesize (g); > //#warning the below reference pass name is wrong for > my_framesize_pass_info > my_framesize_pass_info.reference_pass_name = "rtl- > pro_and_epilogue"; > my_framesize_pass_info.ref_pass_instance_number = 1; > my_framesize_pass_info.pos_op = PASS_POS_INSERT_AFTER; > register_callback (plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, > &my_framesize_pass_info); > > But for some reason I cannot understand the reference_pass_name is > wrong. Using "rtl-pro_and_epilogue" don't work. And I tried many > variants without any success during several hours. > > > So what is the reference_pass_name to use with register_callback > like > above to mention that pass_data_thread_prologue_and_epilogue defined > in > gcc/function.c line 6553 ?
It's been a long time since I touched this code, but the gcc-python- plugin has an example of an RTL pass in a plugin (albeit in Python) https://github.com/davidmalcolm/gcc-python-plugin/blob/master/tests/plugin/new-passes/script.py#L97 I just smoketested it and the pass appears to get run. Specifically, my example registers the plugin pass after "expand" (so I don't think you need the "rtl-" prefix there; I think these prefixes are for dump names rather than pass names). Hope this is helpful Dave > > The entire code (of that proof-of-concept work in progress) is > temporarily available on > http://starynkevitch.net/Basile/chariotdemo-2019-Apr-10-5414f7e3a173. > tar.bz2 > which is a small archive of 14340 bytes. Please notice that the code > I > have written in collaboration with my colleagues Franck Védrine (in > BCC) > and Yves Lhuillier at CEA LIST is under GPLv3+ license. But that > example > also contains some third-party tiny code taken from > https://wiki.osdev.org/Bare_Bones and in good faith we don't know > what > license is that code (files kernel.c etc...) but we guess it is > morally > in the public domain or open source (but we are not lawyers) since > given > as an example on some wiki page. > > Regards > >
