https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116906
Bug ID: 116906 Summary: floating point exception under -O2 optimization Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: middle-end Assignee: unassigned at gcc dot gnu.org Reporter: bouncy12578 at gmail dot com Target Milestone: --- $ gcc -v Using built-in specs. COLLECT_GCC=gcc-14 COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-linux-gnu/14/lto-wrapper OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 14-20240412-0ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-14/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2,rust --prefix=/usr --with-gcc-major-version-only --program-suffix=-14 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/libexec --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-libstdcxx-backtrace --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-14-OQFzmN/gcc-14-14-20240412/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-14-OQFzmN/gcc-14-14-20240412/debian/tmp-gcn/usr --enable-offload-defaulted --without-cuda-driver --enable-checking=yes,extra,rtl --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 14.0.1 20240412 (experimental) [master r14-9935-g67e1433a94f] (Ubuntu 14-20240412-0ubuntu1) $ cat case.c #include <stdint.h> int a = 1, b = 0; uint64_t safe_mod(uint64_t a, uint64_t b) { if (b == 0) return a; else return a % b; } int f(uint64_t p) { int c = 0; j: b = safe_mod( (c = ((a &= (0 < p)) && 1), 1), p); if (!c) goto j; return 0; } int main() { f(b); } $ gcc case.c -o case -O2 && ./case Floating point exception (core dumped) $ gcc case.c -o case -O3 && ./case (infinite loop, the program won't stop) This bug can be reproduced on gcc 11 or higher(gcc 15 not tested). Any further modification would eliminate bug. The program is a designed infinite loop. It would crash only under -O2 optimization. Other optimization levels won't cause crash. btw, could you tell me where is gcc 15 available? Thanks a lot.