https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108402
Bug ID: 108402
Summary: False positive Wuninitialized with
ftrivial-auto-var-init=pattern
Product: gcc
Version: 12.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: pefoley2 at pefoley dot com
Target Milestone: ---
Created attachment 54271
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54271&action=edit
Reduced test case
This error showed up when compiling the upstream Linux kernel with ARCH=um
allyesconfig.
It appears to be specific to the -ftrivial-auto-var-init=pattern option.
Reduced test case attached, extracted from
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/spi/spi-stm32-qspi.c#n519
e.g.
gcc -v -O2 -ftrivial-auto-var-init=pattern -Werror=uninitialized -c qspi.i -o
/dev/null
Using built-in specs.
COLLECT_GCC=gcc
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-12.2.1_p20221231/work/gcc-12-20221231/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/12
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/12/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/12
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/12/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/12/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/12/include/g++-v12
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/12/python
--enable-languages=c,c++,d,go,fortran,ada --enable-obsolete --enable-secureplt
--disable-werror --with-system-zlib --enable-nls --without-included-gettext
--disable-libunwind-exceptions --enable-checking=release
--with-bugurl=https://bugs.gentoo.org/ --with-pkgversion='Gentoo
12.2.1_p20221231 p8' --with-gcc-major-version-only --disable-esp
--enable-libstdcxx-time --disable-libstdcxx-pch --enable-shared
--enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu
--enable-multilib --with-multilib-list=m32,m64 --disable-fixed-point
--enable-targets=all --enable-libgomp --disable-libssp --disable-libada
--disable-cet --disable-systemtap --disable-valgrind-annotations
--enable-vtable-verify --with-zstd --enable-lto --with-isl
--disable-isl-version-check --enable-default-pie --enable-default-ssp
--with-build-config=bootstrap-lto
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.2.1 20221231 (Gentoo 12.2.1_p20221231 p8)
COLLECT_GCC_OPTIONS='-v' '-O2' '-ftrivial-auto-var-init=pattern'
'-Werror=uninitialized' '-c' '-o' '/dev/null' '-mtune=generic' '-march=x86-64'
/usr/libexec/gcc/x86_64-pc-linux-gnu/12/cc1 -fpreprocessed qspi.i -quiet
-dumpbase qspi.i -dumpbase-ext .i -mtune=generic -march=x86-64 -O2
-Werror=uninitialized -version -ftrivial-auto-var-init=pattern -o
/tmp/ccMHYckL.s
GNU C17 (Gentoo 12.2.1_p20221231 p8) version 12.2.1 20221231
(x86_64-pc-linux-gnu)
compiled by GNU C version 12.2.1 20221231, GMP version 6.2.1, MPFR
version 4.2.0, MPC version 1.3.1, isl version isl-0.24-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C17 (Gentoo 12.2.1_p20221231 p8) version 12.2.1 20221231
(x86_64-pc-linux-gnu)
compiled by GNU C version 12.2.1 20221231, GMP version 6.2.1, MPFR
version 4.2.0, MPC version 1.3.1, isl version isl-0.24-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 0fe3c6b2f620dfca480d344f2a96d9ed
qspi.i: In function ‘stm32_qspi_dirmap_read’:
qspi.i:40:20: error: ‘op’ is used uninitialized [-Werror=uninitialized]
40 | struct spi_mem_op op;
| ^~
qspi.i:40:20: note: ‘op’ declared here
40 | struct spi_mem_op op;
| ^~
cc1: some warnings being treated as errors
-fanalyzer additionally reports:
qspi.i: In function ‘stm32_qspi_dirmap_read’:
qspi.i:40:20: warning: use of uninitialized value ‘*(long int *)((char *)&op +
offsetof(struct spi_mem_op, addr.nbytes))’ [CWE-457]
[-Wanalyzer-use-of-uninitialized-value]
40 | struct spi_mem_op op;
| ^~
‘stm32_qspi_dirmap_read’: events 1-2
|
| 40 | struct spi_mem_op op;
| | ^~
| | |
| | (1) region created on stack here
| | (2) use of uninitialized value ‘*(long int
*)((char *)&op + offsetof(struct spi_mem_op, addr.nbytes))’ here
|
qspi.i:40:20: warning: use of uninitialized value ‘*(long int *)((char *)&op +
offsetof(struct spi_mem_op, dummy.nbytes))’ [CWE-457]
[-Wanalyzer-use-of-uninitialized-value]
40 | struct spi_mem_op op;
| ^~
‘stm32_qspi_dirmap_read’: events 1-2
|
| 40 | struct spi_mem_op op;
| | ^~
| | |
| | (1) region created on stack here
| | (2) use of uninitialized value ‘*(long int
*)((char *)&op + offsetof(struct spi_mem_op, dummy.nbytes))’ here
|
qspi.i:40:20: warning: use of uninitialized value ‘*(long int *)((char *)&op +
offsetof(struct spi_mem_op, cmd.nbytes))’ [CWE-457]
[-Wanalyzer-use-of-uninitialized-value]
40 | struct spi_mem_op op;
| ^~
‘stm32_qspi_dirmap_read’: events 1-2
|
| 40 | struct spi_mem_op op;
| | ^~
| | |
| | (1) region created on stack here
| | (2) use of uninitialized value ‘*(long int
*)((char *)&op + offsetof(struct spi_mem_op, cmd.nbytes))’ here
|
