Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Oct 18, 2016 at 11:29:53AM -0400, Steven Rostedt escreveu:
> On Tue, 18 Oct 2016 11:01:09 +0900
> Namhyung Kim <namhyung@kernel.org> wrote:
> 
> > Hi Honggyu,
> > 
> > You need to CC relevant maintainers when you send patches to LKML.
> > For the libtraceevent, they are Arnaldo and Steven.  You can use
> > scripts/get_maintainer.pl for this job later.  In addition running
> > scripts/checkpatch.pl before sending patches is a good habit.
> > 
> > Arnaldo and Steve,
> > 
> > This is from uftrace building libtraceevent with the optimization flag
> > and we want to fix the upstream as well.
> > 
> 
> Acked-by: Steven Rostedt <rostedt@goodmis.org>

So right after applying this patch I get these new warnings, investigating...

[acme@jouet linux]$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/6.2.1/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,objc,obj-c++,fortran,ada,go,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --disable-libgcj --with-isl --enable-libmpx --enable-gnu-indirect-function --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 6.2.1 20160916 (Red Hat 6.2.1-2) (GCC) 
[acme@jouet linux]$ 

  LD       /tmp/build/perf/plugin_mac80211-in.o
kbuffer-parse.c: In function ‘__old_next_event’:
kbuffer-parse.c:339:27: warning: ‘length’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  kbuf->next = kbuf->index + length;
               ~~~~~~~~~~~~^~~~~~~~
kbuffer-parse.c:297:15: note: ‘length’ was declared here
  unsigned int length;
               ^~~~~~
  CC       /tmp/build/perf/plugin_sched_switch.o
  CC       /tmp/build/perf/run-command.o
event-parse.c: In function ‘pevent_find_event_by_name’:
event-parse.c:3513:21: warning: ‘event’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  pevent->last_event = event;
  ~~~~~~~~~~~~~~~~~~~^~~~~~~
  CC       /tmp/build/perf/sigchain.o
  LD       /tmp/build/perf/plugin_sched_switch-in.o
  CC       /tmp/build/perf/plugin_function.o
event-parse.c: In function ‘pevent_data_lat_fmt’:
event-parse.c:5156:4: warning: ‘migrate_disable’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    trace_seq_printf(s, "%d", migrate_disable);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
event-parse.c:5163:4: warning: ‘lock_depth’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    trace_seq_printf(s, "%d", lock_depth);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
plugin_function.c: In function ‘function_handler’:
plugin_function.c:133:6: warning: ‘index’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  int index;
      ^~~~~
  CC       /tmp/build/perf/subcmd-config.o
  GEN      perf-archive
  LD       /tmp/build/perf/plugin_function-in.o
  GEN      perf-with-kcore
  CC       /tmp/build/perf/plugin_xen.o
event-parse.c: In function ‘pevent_event_info’:
event-parse.c:5003:7: warning: ‘len_arg’ may be used uninitialized in this function [-Wmaybe-uninitialized]
       trace_seq_printf(s, format, len_arg, (char)val);
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
event-parse.c:4846:6: note: ‘len_arg’ was declared here
  int len_arg;
      ^~~~~~~
  MKDIR    /tmp/build/perf/util/