rust/src/libstd/thread, branch 1.37.0

Auto merge of #60341 - mtak-:macos-tlv-workaround, r=alexcrichton

2019-06-20T02:36:49+00:00

macos tlv workaround fixes: #60141 Includes: * remove dead code: `requires_move_before_drop`. This hasn't been needed for a while now (oops I should have removed it in #57655) * redox had a copy of `fast::Key` (not sure why?). That has been removed. * Perform a `read_volatile` on OSX to reduce `tlv_get_addr` calls per `__getit` from (4-2 depending on context) to 1. `tlv_get_addr` is relatively expensive (~1.5ns on my machine). Previously, in contexts where `__getit` was inlined, 4 calls to `tlv_get_addr` were performed per lookup. For some reason when `__getit` is not inlined this is reduced to 2x - and performance improves to match. After this PR, I have only ever seen 1x call to `tlv_get_addr` per `__getit`, and macos now benefits from situations where `__getit` is inlined. I'm not sure if the `read_volatile(&&__KEY)` trick is working around an LLVM bug, or a rustc bug, or neither. r? @alexcrichton

fix wasm unused import in thread local implementation

2019-05-15T21:35:24+00:00

llvm makes good inlining choices with only the #[cold] attribute

2019-05-15T14:30:34+00:00

remove trailing whitespace

2019-05-15T14:30:34+00:00

cold was necessary on try_initialize_nodrop to get more straight line asm

2019-05-15T14:30:34+00:00

- remove unnecessary inlines

2019-05-15T14:30:34+00:00

- add comment explaining that the fast::Key data structure was carefully constructed for fast access on OSX - remove inline(never) from the initializer for types where `needs_drop::()` is false

add #[allow(unused)]

2019-05-15T14:30:34+00:00

restructure thread_local! for better codegen (especially on macos)

2019-05-15T14:30:33+00:00

Revert "ensure fast thread local lookups occur once per access on macos"

2019-05-15T14:30:33+00:00

This reverts commit d252f3b77f3b7d4cd59620588f9d026633c05816.

ensure fast thread local lookups occur once per access on macos

2019-05-15T14:30:33+00:00