https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96930
--- Comment #6 from Gabriel Ravier <gabravier at gmail dot com> ---
For this exact code :
unsigned f(unsigned a, unsigned b)
{
return a / (unsigned long long)(1U << b);
}
compiled with a trunk-based GCC built yesterday for x86-64-linux-gnu configured
with: ../gcc-trunk-20210102/configure
--prefix=/opt/compiler-explorer/gcc-build/staging --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu --disable-bootstrap
--enable-multiarch --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --enable-clocale=gnu --enable-languages=c,c++,fortran,ada,d
--enable-ld=yes --enable-gold=yes --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-linker-build-id --enable-lto
--enable-plugins --enable-threads=posix
--with-pkgversion=Compiler-Explorer-Build
with the specific compiler command line of `g++ -g -o
/tmp/compiler-explorer-compiler202103-4524-15mdddx.f4b4g/output.s -masm=intel
-S -fdiagnostics-color=always -O3
/tmp/compiler-explorer-compiler202103-4524-15mdddx.f4b4g/example.cpp`, I get:
f(unsigned int, unsigned int):
mov eax, edi
mov ecx, esi
shr rax, cl
ret
whereas LLVM uses `shr eax, cl` instead.
See also https://godbolt.org/z/Gqza7v for the exact setup I used (in case I
missed something and you rather avoid having to wait for me to answer).
