When lowering a struct type to an LLVM struct type, keep track of
whether there are any underaligned fields. If so, then make it a packed
llvm struct. This works because we already insert manual padding bytes
regardless.
We could unconditionally use an LLVM packed struct; the reason we bother
checking for underaligned fields is that it is a conservative choice, in
case LLVM handles packed structs less optimally. A future improvement
could simplify this code by unconditionally using packed LLVM structs
and then make sure measure perf is unaffected.
closes#12190
* std lib tests are passing on x86_64-linux with and without -lc
* stage2 is building from source on x86_64-linux
* down to 38 remaining uses of `usingnamespace`
Cross-platform versions of msghdr, sendmsg, recvmsg, linger, and iovec
were provided based on findings from glibc, musl, and Microsoft's
documentation.
Implemented initial Reactor interface for epoll (linux) which wraps
around I/O reactor subsystems such as epoll, kqueue, select, etc. across
different platforms. The Reactor interface allows for driving async I/O
in Zig applications.
A test was added for the Reactor interface to drive a TCP
client/listener socket pair.
A greatest-common-subset of possible socket initialization flags (close
socket on exec syscalls, initialize socket to be non-blocking) were
implemented.
A test was added for using sendmsg/recvmsg syscalls across different
platforms for a TCP client/listener socket pair.
