[libc-commits] [libc] [libc][setjmp][x86] implement setjmp in terms of out of line asm (PR #88157)

[Nick Desaulniers via libc-commits]

nickdesaulniers wrote:

As to what's unsupported for mach-o:
```sh
$ clang libc/src/setjmp/x86_64/setjmp.S -c --target=x86_64-darwin
libc/src/setjmp/x86_64/setjmp.S:28:1: error: unknown directive
.type setjump, @function
^
libc/src/setjmp/x86_64/setjmp.S:29:1: error: unknown directive
.type _ZN22LIBC_NAMESPACE6setjmpEP9__jmp_buf, @function
^
libc/src/setjmp/x86_64/setjmp.S:47:1: error: unknown directive
.size setjump, . - setjump
^
libc/src/setjmp/x86_64/setjmp.S:48:1: error: unknown directive
.size _ZN22LIBC_NAMESPACE6setjmpEP9__jmp_buf, . - _ZN22LIBC_NAMESPACE6setjmpEP9__jmp_buf
^
libc/src/setjmp/x86_64/setjmp.S:50:19: error: unexpected token in '.section' directive
.section .note.GNU-stack, "", @progbits
                  ^
```

https://github.com/llvm/llvm-project/pull/88157