https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90954
Bug ID: 90954
Summary: ICE: combining undefined behavior sanitizer with
openmp
Product: gcc
Version: 8.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: frans at svi dot nl
Target Milestone: ---
Created attachment 46506
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46506&action=edit
preprocessed source resulting from the gcc run when the ICE occurs
When compiling OpenMP parallel code with the undefined behavior sanitizer
enabled, I encountered an internal compiler error. I reduced the problem to the
following small example:
--- start bug.c ---
#include <stdio.h>
#include <omp.h>
int main(void)
{
float sum = 0.0f;
int i;
#pragma omp parallel for
for (i = 0; i < 10; i++) {
float a, b;
a = 1.0f;
b = 2.0f;
#pragma omp atomic
sum += a / b;
}
printf("sum = %g \n", sum);
return 0;
}
--- end bug.c ---
Running it with the version of gcc-8 that is in current Ubuntu 18.04 LTS
without the undefined behavior sanitizer has the expected result:
$ gcc-8 -v -save-temps -Wall -Wextra -fopenmp -o bug bug.c
Using built-in specs.
COLLECT_GCC=gcc-8
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
8.3.0-6ubuntu1~18.04.1' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-8
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie
--with-system-zlib --with-target-system-zlib --enable-objc-gc=auto
--enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 8.3.0 (Ubuntu 8.3.0-6ubuntu1~18.04.1)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fopenmp' '-o' 'bug'
'-mtune=generic' '-march=x86-64' '-pthread'
/usr/lib/gcc/x86_64-linux-gnu/8/cc1 -E -quiet -v -imultiarch x86_64-linux-gnu
-D_REENTRANT bug.c -mtune=generic -march=x86-64 -Wall -Wextra -fopenmp
-fpch-preprocess -fstack-protector-strong -Wformat-security -o bug.i
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/8/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/gcc/x86_64-linux-gnu/8/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/8/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fopenmp' '-o' 'bug'
'-mtune=generic' '-march=x86-64' '-pthread'
/usr/lib/gcc/x86_64-linux-gnu/8/cc1 -fpreprocessed bug.i -quiet -dumpbase
bug.c -mtune=generic -march=x86-64 -auxbase bug -Wall -Wextra -version -fopenmp
-fstack-protector-strong -Wformat-security -o bug.s
GNU C17 (Ubuntu 8.3.0-6ubuntu1~18.04.1) version 8.3.0 (x86_64-linux-gnu)
compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.1,
MPC version 1.1.0, isl version isl-0.19-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C17 (Ubuntu 8.3.0-6ubuntu1~18.04.1) version 8.3.0 (x86_64-linux-gnu)
compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.1,
MPC version 1.1.0, isl version isl-0.19-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 8630479b05639af80099f29538a134fa
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fopenmp' '-o' 'bug'
'-mtune=generic' '-march=x86-64' '-pthread'
as -v --64 -o bug.o bug.s
GNU assembler version 2.30 (x86_64-linux-gnu) using BFD version (GNU Binutils
for Ubuntu) 2.30
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/8/../../../:/lib/:/usr/lib/
Reading specs from /usr/lib/gcc/x86_64-linux-gnu/8/libgomp.spec
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fopenmp' '-o' 'bug'
'-mtune=generic' '-march=x86-64' '-pthread'
/usr/lib/gcc/x86_64-linux-gnu/8/collect2 -plugin
/usr/lib/gcc/x86_64-linux-gnu/8/liblto_plugin.so
-plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
-plugin-opt=-fresolution=bug.res -plugin-opt=-pass-through=-lgcc
-plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lpthread
-plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc
-plugin-opt=-pass-through=-lgcc_s --build-id --eh-frame-hdr -m elf_x86_64
--hash-style=gnu --as-needed -dynamic-linker /lib64/ld-linux-x86-64.so.2 -pie
-z now -z relro -o bug
/usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/Scrt1.o
/usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/crti.o
/usr/lib/gcc/x86_64-linux-gnu/8/crtbeginS.o
/usr/lib/gcc/x86_64-linux-gnu/8/crtoffloadbegin.o
-L/usr/lib/gcc/x86_64-linux-gnu/8
-L/usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu
-L/usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib -L/lib/x86_64-linux-gnu
-L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib
-L/usr/lib/gcc/x86_64-linux-gnu/8/../../.. bug.o -lgomp -lgcc --push-state
--as-needed -lgcc_s --pop-state -lpthread -lc -lgcc --push-state --as-needed
-lgcc_s --pop-state /usr/lib/gcc/x86_64-linux-gnu/8/crtendS.o
/usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/crtn.o
/usr/lib/gcc/x86_64-linux-gnu/8/crtoffloadend.o
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fopenmp' '-o' 'bug'
'-mtune=generic' '-march=x86-64' '-pthread'
$ ./bug
sum = 5
However, running it with the undefined behavior sanitizer results in an
internal compiler error:
$ gcc-8 -v -save-temps -Wall -Wextra -fsanitize=undefined -fopenmp -o bug bug.c
Using built-in specs.
COLLECT_GCC=gcc-8
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
8.3.0-6ubuntu1~18.04.1' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-8
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie
--with-system-zlib --with-target-system-zlib --enable-objc-gc=auto
--enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 8.3.0 (Ubuntu 8.3.0-6ubuntu1~18.04.1)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fsanitize=undefined'
'-fopenmp' '-o' 'bug' '-mtune=generic' '-march=x86-64' '-pthread'
/usr/lib/gcc/x86_64-linux-gnu/8/cc1 -E -quiet -v -imultiarch x86_64-linux-gnu
-D_REENTRANT bug.c -mtune=generic -march=x86-64 -Wall -Wextra
-fsanitize=undefined -fopenmp -fpch-preprocess -fstack-protector-strong
-Wformat-security -o bug.i
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/8/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/gcc/x86_64-linux-gnu/8/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/8/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-Wall' '-Wextra' '-fsanitize=undefined'
'-fopenmp' '-o' 'bug' '-mtune=generic' '-march=x86-64' '-pthread'
/usr/lib/gcc/x86_64-linux-gnu/8/cc1 -fpreprocessed bug.i -quiet -dumpbase
bug.c -mtune=generic -march=x86-64 -auxbase bug -Wall -Wextra -version
-fsanitize=undefined -fopenmp -fstack-protector-strong -Wformat-security -o
bug.s
GNU C17 (Ubuntu 8.3.0-6ubuntu1~18.04.1) version 8.3.0 (x86_64-linux-gnu)
compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.1,
MPC version 1.1.0, isl version isl-0.19-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C17 (Ubuntu 8.3.0-6ubuntu1~18.04.1) version 8.3.0 (x86_64-linux-gnu)
compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.1,
MPC version 1.1.0, isl version isl-0.19-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 8630479b05639af80099f29538a134fa
bug.c: In function ‘main’:
bug.c:16:9: internal compiler error: in c_finish_omp_atomic, at
c-family/c-omp.c:303
sum += a / b;
^~~
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-8/README.Bugs> for instructions.
--- end of output ---
The problem also occurs in other versions of gcc that are included in Ubuntu.
Attached is "bug.i" from the run that produces the ICE.
