https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110446
Bug ID: 110446 Summary: [14 Regression] Wrong code at -O1/2/3/s on x86_64-pc-linux-gnu Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: jwzeng at nuaa dot edu.cn Target Milestone: --- Link to the Compiler Explorer: https://godbolt.org/z/jE9fxsYfE The following code snippet: #include <stdio.h> unsigned int a = 1387579096U; int main() { a = 1 < (~a) ? 1 : (~a); printf("%u\n", a); return 0; } > $ /usr/gcc-trunk/bin/gcc -O0 bug.c; ./a.out > 1 > $ /usr/gcc-trunk/bin/gcc -O1 bug.c; ./a.out > 2907388199 > $ /usr/gcc-trunk/bin/gcc -O2 bug.c; ./a.out > 2907388199 > $ /usr/gcc-trunk/bin/gcc -O3 bug.c; ./a.out > 2907388199 > $ /usr/gcc-trunk/bin/gcc -Os bug.c; ./a.out > 2907388199 When compiled with -O1/2/3/s, it prints the wrong result 2907388199 instead of 1. Earlier GCCs do not have this bug. > $ /usr/gcc-trunk/bin/gcc --version Using built-in specs. COLLECT_GCC=/home/compilers/gcc/gcc-trunk/bin/gcc COLLECT_LTO_WRAPPER=/home/compilers/gcc/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../gcc-trunk-source/gcc/configure --enable-languages=c,c++,fortran --enable-checking=release --enable-valgrind-annotations --disable-werror --disable-libstdcxx-pch --enable-libgomp --enable-lto --enable-gold --with-plugin-ld=gold --prefix=/usr/local/gcc-trunk Thread model: posix Supported LTO compression algorithms: zlib gcc version 14.0.0 20230619 (experimental) [master r14-1917-gf8e0270272] (GCC)