[llvm-dev] [X86] How do I set just the low byte of an x86_64 register?

[Tim Northover via llvm-dev]

On Thu, 11 Feb 2021 at 13:29, Mat Hostetter via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> But even on CPUs where there is a stall that's worse than the added instructions from not using movb, -Os should still prefer movb.

It doesn't really change anything (we still don't do movb), but
Clang's real size optimization option is "-Oz". -Os is much closer to
-O2 with just a hint of caring about size.

Cheers.

Tim.