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 <
marc@nieper-wisskirchen.de>:

> Am Sa., 15. Jan. 2022 um 14:56 Uhr schrieb Marc Nieper-Wißkirchen
> <marc@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 <
> jeffreyalaw@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
> > >
>