For reference, clang targeting MSVC mode can do this: $ clang t.cpp -target x86_64-pc-win32 -S -emit-llvm -o - | opt -S -sroa -instcombine | grep 'ret i1'

For reference, clang targeting MSVC mode can do this: $ clang t.cpp -target x86_64-pc-win32 -S -emit-llvm -o - | opt -S -sroa -instcombine | grep 'ret i1' ret i1 false