Re: libtracevent build warnings on Clear Linux (gcc 8.2.0)

From: Steven Rostedt
Date: Fri Aug 24 2018 - 09:43:05 EST

On Mon, 20 Aug 2018 10:39:43 -0300
Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:

> Hi guys,
>
> I noticed this while working on a new perf build container for the Clear
> Linux distro, can you take a look at it so that we get the build clean on Clear?

These all look like the compiler is being stupid. Do you think we
really need to address it?

-- Steve

>
> - Arnaldo
>
> root@28864dcfe31b /git/perf # gcc -v
> Using built-in specs.
> COLLECT_GCC=gcc
> COLLECT_LTO_WRAPPER=/usr/lib64/gcc/x86_64-generic-linux/8.2.0/lto-wrapper
> Target: x86_64-generic-linux
> Configured with: ../gcc-8.2.0/configure --prefix=/usr --with-pkgversion='Clear Linux OS for Intel Architecture' --libdir=/usr/lib64 --enable-libstdcxx-pch --libexecdir=/usr/lib64 --with-system-zlib --enable-shared --enable-gnu-indirect-function --disable-vtable-verify --enable-threads=posix --enable-__cxa_atexit --enable-plugin --enable-ld=default --enable-clocale=gnu --disable-multiarch --enable-multilib --enable-lto --enable-linker-build-id --build=x86_64-generic-linux --target=x86_64-generic-linux --enable-languages=c,c++,fortran,go --enable-bootstrap --with-ppl=yes --with-isl --includedir=/usr/include --with-gxx-include-dir=/usr/include/c++/ --exec-prefix=/usr --with-glibc-version=2.19 --disable-libunwind-exceptions --with-gnu-ld --with-tune=haswell --with-arch=westmere --disable-libmpx
> Thread model: posix
> gcc version 8.2.0 (Clear Linux OS for Intel Architecture)
> root@28864dcfe31b /git/perf #
>
> root@28864dcfe31b /git # swupd bundle-add c-basic
> Downloading packs...
>
> Extracting c-basic pack for version 24500
> ...50%
> Extracting perl-basic pack for version 24430
> ...100%
> Starting download of remaining update content. This may take a while...
> ...100%
> Finishing download of update content...
> Installing bundle(s) files...
> ...100%
> Calling post-update helper scripts.
> Successfully installed 1 bundle
> root@28864dcfe31b /git #
> root@28864dcfe31b /git/perf # make -C tools/perf O=/tmp/build/perf
> make: Entering directory '/git/perf/tools/perf'
> BUILD: Doing 'make -j4' parallel build
> HOSTCC /tmp/build/perf/fixdep.o
> HOSTLD /tmp/build/perf/fixdep-in.o
> LINK /tmp/build/perf/fixdep
>
> Auto-detecting system features:
> ... dwarf: [ OFF ]
> ... dwarf_getlocations: [ OFF ]
> ... glibc: [ on ]
> ... gtk2: [ OFF ]
> ... libaudit: [ OFF ]
> ... libbfd: [ on ]
> ... libelf: [ OFF ]
> ... libnuma: [ OFF ]
> ... numa_num_possible_cpus: [ OFF ]
> ... libperl: [ on ]
> ... libpython: [ OFF ]
> ... libslang: [ OFF ]
> ... libcrypto: [ OFF ]
> ... libunwind: [ OFF ]
> ... libdw-dwarf-unwind: [ OFF ]
> ... zlib: [ on ]
> ... lzma: [ OFF ]
> ... get_cpuid: [ on ]
> ... bpf: [ on ]
>
> Makefile.config:318: No libelf found. Disables 'probe' tool, jvmti and BPF support in 'perf record'. Please install libelf-dev, libelf-devel or elfutils-libelf-devel
> Makefile.config:445: No sys/sdt.h found, no SDT events are defined, please install systemtap-sdt-devel or systemtap-sdt-dev
> Makefile.config:518: Disabling post unwind, no support found.
> Makefile.config:583: No libcrypto.h found, disables jitted code injection, please install libssl-devel or libssl-dev
> Makefile.config:598: slang not found, disables TUI support. Please install slang-devel, libslang-dev or libslang2-dev
> Makefile.config:612: GTK2 not found, disables GTK2 support. Please install gtk2-devel or libgtk2.0-dev
> Makefile.config:666: No python interpreter was found: disables Python support - please install python-devel/python-dev
> Makefile.config:750: No liblzma found, disables xz kernel module decompression, please install xz-devel/liblzma-dev
> Makefile.config:763: No numa.h found, disables 'perf bench numa mem' benchmark, please install numactl-devel/libnuma-devel/libnuma-dev
> Makefile.config:814: No libbabeltrace found, disables 'perf data' CTF format support, please install libbabeltrace-dev[el]/libbabeltrace-ctf-dev
> GEN /tmp/build/perf/common-cmds.h
> MKDIR /tmp/build/perf/fd/
> CC /tmp/build/perf/fd/array.o
> CC /tmp/build/perf/event-parse.o
> LD /tmp/build/perf/fd/libapi-in.o
> MKDIR /tmp/build/perf/fs/
> CC /tmp/build/perf/fs/fs.o
> MKDIR /tmp/build/perf/fs/
> CC /tmp/build/perf/fs/tracing_path.o
> LD /tmp/build/perf/fs/libapi-in.o
> CC /tmp/build/perf/cpu.o
> CC /tmp/build/perf/debug.o
> CC /tmp/build/perf/str_error_r.o
> LD /tmp/build/perf/libapi-in.o
> AR /tmp/build/perf/libapi.a
> CC /tmp/build/perf/exec-cmd.o
> MKDIR /tmp/build/perf/pmu-events/
> HOSTCC /tmp/build/perf/pmu-events/json.o
> event-parse.c: In function âtep_find_event_by_nameâ:
> event-parse.c:3519:21: warning: âeventâ may be used uninitialized in this function [-Wmaybe-uninitialized]
> pevent->last_event = event;
> ~~~~~~~~~~~~~~~~~~~^~~~~~~
> MKDIR /tmp/build/perf/pmu-events/
> event-parse.c: In function âtep_data_lat_fmtâ:
> event-parse.c:5198:4: warning: âmigrate_disableâ may be used uninitialized in this function [-Wmaybe-uninitialized]
> trace_seq_printf(s, "%d", migrate_disable);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> event-parse.c:5205:4: warning: âlock_depthâ may be used uninitialized in this function [-Wmaybe-uninitialized]
> trace_seq_printf(s, "%d", lock_depth);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> HOSTCC /tmp/build/perf/pmu-events/jsmn.o
> event-parse.c: In function âtep_event_infoâ:
> event-parse.c:5045:7: warning: âlen_argâ may be used uninitialized in this function [-Wmaybe-uninitialized]
> trace_seq_printf(s, format, len_arg, (char)val);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> event-parse.c:4882:6: note: âlen_argâ was declared here
> int len_arg;
> ^~~~~~~
> event-parse.c:4336:11: warning: âvsizeâ may be used uninitialized in this function [-Wmaybe-uninitialized]
> val = tep_read_number(pevent, bptr, vsize);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> event-parse.c:4222:6: note: âvsizeâ was declared here
> int vsize;
> ^~~~~
> CC /tmp/build/perf/help.o
>