Hi Jeff and David, any news on this fix?
Thanks, Marc Am Mo., 31. Jan. 2022 um 12:42 Uhr schrieb Marc Nieper-Wißkirchen <m...@nieper-wisskirchen.de>: > > Attached to this email is the patch updated to the recent renaming from *.c > to *.cc. > > > Am So., 23. Jan. 2022 um 14:18 Uhr schrieb Marc Nieper-Wißkirchen > <m...@nieper-wisskirchen.de>: >> >> Am Sa., 15. Jan. 2022 um 14:56 Uhr schrieb Marc Nieper-Wißkirchen >> <m...@nieper-wisskirchen.de>: >> > >> > Jeff, David, do you need any more input from my side? >> > >> > -- Marc >> > >> > Am Sa., 8. Jan. 2022 um 17:32 Uhr schrieb Jeff Law <jeffreya...@gmail.com>: >> > > >> > > >> > > >> > > On 1/6/2022 6:53 AM, David Malcolm via Gcc-patches wrote: >> > > > On Sun, 2021-12-19 at 22:30 +0100, Marc Nieper-Wißkirchen wrote: >> > > >> This patch fixes a memory leak in the pass manager. In the existing >> > > >> code, >> > > >> the m_name_to_pass_map is allocated in >> > > >> pass_manager::register_pass_name, but >> > > >> never deallocated. This is fixed by adding a deletion in >> > > >> pass_manager::~pass_manager. Moreover the string keys in >> > > >> m_name_to_pass_map are >> > > >> all dynamically allocated. To free them, this patch adds a new hash >> > > >> trait for >> > > >> string hashes that are to be freed when the corresponding hash entry >> > > >> is removed. >> > > >> >> > > >> This fix is particularly relevant for using GCC as a library through >> > > >> libgccjit. >> > > >> The memory leak also occurs when libgccjit is instructed to use an >> > > >> external >> > > >> driver. >> > > >> >> > > >> Before the patch, compiling the hello world example of libgccjit with >> > > >> the external driver under Valgrind shows a loss of 12,611 (48 direct) >> > > >> bytes. After the patch, no memory leaks are reported anymore. >> > > >> (Memory leaks occurring when using the internal driver are mostly in >> > > >> the driver code in gcc/gcc.c and have to be fixed separately.) >> > > >> >> > > >> The patch has been tested by fully bootstrapping the compiler with >> > > >> the >> > > >> frontends C, C++, Fortran, LTO, ObjC, JIT and running the test suite >> > > >> under a x86_64-pc-linux-gnu host. >> > > > Thanks for the patch. >> > > > >> > > > It looks correct to me, given that pass_manager::register_pass_name >> > > > does an xstrdup and puts the result in the map. >> > > > >> > > > That said: >> > > > - I'm not officially a reviewer for this part of gcc (though I probably >> > > > touched this code last) >> > > > - is it cleaner to instead change m_name_to_pass_map's key type from >> > > > const char * to char *, to convey that the map "owns" the name? That >> > > > way we probably wouldn't need struct typed_const_free_remove, and (I >> > > > hope) works better with the type system. >> > > > >> > > > Dave >> > > > >> > > >> gcc/ChangeLog: >> > > >> >> > > >> PR jit/63854 >> > > >> * hash-traits.h (struct typed_const_free_remove): New. >> > > >> (struct free_string_hash): New. >> > > >> * pass_manager.h: Use free_string_hash. >> > > >> * passes.c (pass_manager::register_pass_name): Use >> > > >> free_string_hash. >> > > >> (pass_manager::~pass_manager): Delete allocated >> > > >> m_name_to_pass_map. >> > > My concern (and what I hadn't had time to dig into) was we initially >> > > used nofree_string_hash -- I wanted to make sure there wasn't any path >> > > where the name came from the stack (can't be free'd), was saved >> > > elsewhere (danging pointer) and the like. ie, why were we using >> > > nofree_string_hash to begin with? I've never really mucked around with >> > > these bits, so the analysis side kept falling off the daily todo list. >> >> The only occurrences of m_name_to_pass_map are in pass-manager.h >> (where it is defined as a private field of the class pass_manager) and >> in passes.cc. There is just one instance where a name is added to the >> map in passes.cc, namely through the put method. There, the name has >> been xstrdup'ed. >> >> The name (as a const char *) escapes the pass map in >> pass_manager::create_pass_tab through the call to >> m_name_pass_map->traverse. This inserts the name into the pass_tab, >> which is a static vec of const char *s. The pass_tab does not escape >> the translation unit of passes.c. It is used in dump_one_pass where >> the name is used as an argument to fprintf. The important point is >> that it is not freed and not further copied. >> >> > > >> > > If/once you're comfortable with the patch David, then go ahead and apply >> > > it on Marc's behalf. >> > > >> > > jeff >> > >
