[Bug target/92149] Enefficient x86_64 code

[maxim.yegorushkin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92149

--- Comment #2 from Maxim Egorushkin <maxim.yegorushkin at gmail dot com> ---
I notice that g++ always zeros out unused high-order bits. Clang++ never does.
Both follow the same System V ABI.