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b39c2a57a0
When compiling perf tool code with gcc 4.4.7 I'm getting following error: CC util/session.o cc1: warnings being treated as errors util/session.c: In function ‘perf_session_deliver_event’: tools/perf/util/include/linux/bitops.h:109: error: dereferencing pointer ‘p’ does break strict-aliasing rules tools/perf/util/include/linux/bitops.h:101: error: dereferencing pointer ‘p’ does break strict-aliasing rules util/session.c:697: note: initialized from here tools/perf/util/include/linux/bitops.h:101: note: initialized from here make[1]: *** [util/session.o] Error 1 make: *** [util/session.o] Error 2 The aliased types here are u64 and unsigned long pointers, which is safe for the find_first_bit processing. This error shows up for me only for gcc 4.4 on 32bit x86, even for -Wstrict-aliasing=3, while newer gcc are quiet and scream here for -Wstrict-aliasing={2,1}. Looks like newer gcc changed the rules for strict alias warnings. The gcc documentation offers workaround for valid aliasing by using __may_alias__ attribute: http://gcc.gnu.org/onlinedocs/gcc-4.4.0/gcc/Type-Attributes.html Using this workaround for the find_first_bit function. Signed-off-by: Jiri Olsa <jolsa@redhat.com> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1393434867-20271-1-git-send-email-jolsa@redhat.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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.. | ||
arch | ||
bench | ||
config | ||
Documentation | ||
python | ||
scripts | ||
tests | ||
ui | ||
util | ||
.gitignore | ||
builtin-annotate.c | ||
builtin-bench.c | ||
builtin-buildid-cache.c | ||
builtin-buildid-list.c | ||
builtin-diff.c | ||
builtin-evlist.c | ||
builtin-help.c | ||
builtin-inject.c | ||
builtin-kmem.c | ||
builtin-kvm.c | ||
builtin-list.c | ||
builtin-lock.c | ||
builtin-mem.c | ||
builtin-probe.c | ||
builtin-record.c | ||
builtin-report.c | ||
builtin-sched.c | ||
builtin-script.c | ||
builtin-stat.c | ||
builtin-timechart.c | ||
builtin-top.c | ||
builtin-trace.c | ||
builtin.h | ||
command-list.txt | ||
CREDITS | ||
design.txt | ||
Makefile | ||
Makefile.perf | ||
MANIFEST | ||
perf-archive.sh | ||
perf-completion.sh | ||
perf.c | ||
perf.h |