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From: "matt at use dot net" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug bootstrap/50148] GCC fails to bootstrap with -O3 due to "may be used uninitialized" errors Date: Tue, 18 Dec 2012 17:27:00 -0000 [thread overview] Message-ID: <bug-50148-4-xKSRXHp7i0@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-50148-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50148 --- Comment #6 from Matt Hargett <matt at use dot net> 2012-12-18 17:26:54 UTC --- Applying the supplied patch reveals another issue underneath, which is a false positive: /work/mhargett/gcc-trunk-obj/./prev-gcc/xg++ -B/work/mhargett/gcc-trunk-obj/./prev-gcc/ -B/u/mhargett/x86_64-unknown-linux-gnu/bin/ -nostdinc++ -B/work/mhargett/gcc-trunk-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs -B/work/mhargett/gcc-trunk-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/libsupc++/.libs -I/work/mhargett/gcc-trunk-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/include/x86_64-unknown-linux-gnu -I/work/mhargett/gcc-trunk-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/include -I/work/mhargett/gcc-trunk/libstdc++-v3/libsupc++ -L/work/mhargett/gcc-trunk-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs -L/work/mhargett/gcc-trunk-obj/prev-x86_64-unknown-linux-gnu/libstdc++-v3/libsupc++/.libs -g -O2 -O3 -march=nocona -mtune=core2 -floop-block -floop-interchange -floop-strip-mine -flto=jobserver -frandom-seed=1 -DIN_GCC -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wmissing-format-attribute -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -Werror -fno-common -DHAVE_CONFIG_H -static-libstdc++ -static-libgcc -o gengtype \ gengtype.o gengtype-lex.o gengtype-parse.o gengtype-state.o version.o errors.o libcommon.a ../libcpp/libcpp.a ../libiberty/libiberty.a ../libdecnumber/libdecnumber.a ../libbacktrace/.libs/libbacktrace.a libcommon.a ../libcpp/libcpp.a ../libbacktrace/.libs/libbacktrace.a ../libiberty/libiberty.a ../libdecnumber/libdecnumber.a In file included from ../../gcc-trunk/libiberty/cp-demangle.c:876:0, from :51: ../../gcc-trunk/libbacktrace/elf.c: In function ‘elf_add’: ../../gcc-trunk/libbacktrace/mmapio.c:98:14: error: ‘ehdr_view.len’ may be used uninitialized in this function [-Werror=maybe-uninitialized] if (munmap (const_cast.v, view->len) < 0) ^ In file included from ../../gcc-trunk/libiberty/cp-demangle.c:879:0, from :51: ../../gcc-trunk/libbacktrace/elf.c:476:25: note: ‘ehdr_view.len’ was declared here struct backtrace_view ehdr_view; ^ In file included from ../../gcc-trunk/libiberty/cp-demangle.c:876:0, from :51: ../../gcc-trunk/libbacktrace/mmapio.c:98:14: error: ‘ehdr_view.base’ may be used uninitialized in this function [-Werror=maybe-uninitialized] if (munmap (const_cast.v, view->len) < 0) ^ In file included from ../../gcc-trunk/libiberty/cp-demangle.c:879:0, from :51: ../../gcc-trunk/libbacktrace/elf.c:476:25: note: ‘ehdr_view.base’ was declared here struct backtrace_view ehdr_view; ^ In file included from ../../gcc-trunk/libiberty/cp-demangle.c:879:0, from :51: ../../gcc-trunk/libbacktrace/elf.c:516:10: error: ‘ehdr_view.data’ may be used uninitialized in this function [-Werror=maybe-uninitialized] memcpy (&ehdr, ehdr_view.data, sizeof ehdr); ^ In file included from ../../gcc-trunk/libiberty/cp-demangle.c:879:0, from :51: ../../gcc-trunk/libbacktrace/elf.c:476:25: note: ‘ehdr_view.data’ was declared here struct backtrace_view ehdr_view; ^ lto1: all warnings being treated as errors make[4]: *** [/tmp/ccQGEpYR.ltrans15.ltrans.o] Error 1 in libbacktrace/elf.c, elf_add() calls backtrace_get_view(..., &ehdr_view). ehdr_view isn't initialized. backtrace_get_view() will return 1 and leave edhr_view uninitialized, but the potential uninitialized use of ehdr_view is guarded in get_elf() with a 'goto fail'. Therefore, the uninitialized ehdr_view would never get to backtrace_release_view(). Let me know if I should file a separate bug for this.
next prev parent reply other threads:[~2012-12-18 17:27 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-08-21 21:12 [Bug bootstrap/50148] New: " d.g.gorbachev at gmail dot com 2011-08-21 21:15 ` [Bug bootstrap/50148] " d.g.gorbachev at gmail dot com 2011-08-24 21:23 ` pinskia at gcc dot gnu.org 2011-08-24 22:10 ` pinskia at gcc dot gnu.org 2011-12-14 21:23 ` matt at use dot net 2012-12-17 19:12 ` matt at use dot net 2012-12-18 17:27 ` matt at use dot net [this message] 2013-01-07 22:15 ` matt at use dot net 2013-01-08 9:45 ` rguenth at gcc dot gnu.org
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