This will help C++ code that uses exceptions to be tinier. For example,
this change shaves away 1000 lines of assembly code from LLVM's libcxx,
which is 0.7% of all assembly instructions in the entire library.
At least in neovim, `│vi:` is not recognized as a modeline because it
has no preceding whitespace. After fixing this, opening a file yields
an error because `net` is not an option. (`noet`, however, is.)
As of now, the syscall function is implemented as alike to how the
linux kernel sycall ABI works, returning -errno upon errors without
setting the value of errno. However, this does not conform to the
expectations of most software, which expect it to return -1 and set
errno, which is how it works on other libcs, which document it
accordingly:
> The return value is defined by the system call being invoked. In
> general, a 0 return value indicates success. A -1 return value
> indicates an error, and an error number is stored in errno.
- Linux man-pages, syscall(2)
> The return value is the return value from the system call, unless
> the system call failed. In that case, ‘syscall’ returns ‘-1’ and
> sets ‘errno’ to an error code that the system call returned.
- glibc manual, (libc)System Calls
> When the C-bit is set, syscall returns -1 and sets the external
> variable errno (see intro(2)).
- 4BSD manual, syscall(2)
> A -1 return value indicates an error, and an error code is stored in
> errno.
- 4.4BSD, FreeBSD, OpenBSD and NetBSD manuals (same quote is found in
all of them), syscall(2)
This patch corrects the syscall function to work in the same way as in
other libcs.
