GCC just so happens to not select any instructions with alignment requirements at `-msse -mno-sse2`, while clang emits calls to soft-fp functions that aren't im

GCC just so happens to not select any instructions with alignment requirements at `-msse -mno-sse2`, while clang emits calls to soft-fp functions that aren't implemented in the kernel. At -msse2, clang emits sse2 instructions with alignment requirements. You'd think their 16B-aligned-stack driver would be ok, but its caller (the rest of the kernel) has a different ABI (8B-aligned-stack) which is kind of insane to mix TUs with two different ABIs in the same executable and make calls between them. Then again, all x86_64 processors support sse2, so I'm not surprised that Clang at -mno-sse2 doesn't work better. There's numerous bugs filed against Clang where it crashes when -mno-sse2 is set, but double precision floating point is used. (I've spent almost all of this week debugging this, and working with CrOS and AMD engineers on this. It's not clear to me at this point whether the 16B-stack-alignment ABI change was well intentioned or a stroke of luck).