This commit resolves the race condition in the `get_mut` and
`make_unique` functions, which arose through interaction with weak
pointers. The basic strategy is to "lock" the weak pointer count when
trying to establish uniqueness, by reusing the field as a simple
spinlock. The overhead for normal use of `Arc` is expected to be minimal
-- it will be *none* when only strong pointers are used, and only
requires a move from atomic increment to CAS for usage of weak pointers.
The commit also removes the `unsafe` and deprecated status of these functions.
Closes#24880
r? @alexcrichton
cc @metajack @SimonSapin @Ms2ger
This commit resolves the race condition in the `get_mut` and
`make_unique` functions, which arose through interaction with weak
pointers. The basic strategy is to "lock" the weak pointer count when
trying to establish uniqueness, by reusing the field as a simple
spinlock. The overhead for normal use of `Arc` is expected to be minimal
-- it will be *none* when only strong pointers are used, and only
requires a move from atomic increment to CAS for usage of weak pointers.
The commit also removes the `unsafe` and deprecated status of these
functions.
Along the way, the commit also improves several memory orderings, and
adds commentary about why various orderings suffice.
The current split between create_datums_for_fn_args, copy_args_to_allocas and
store_arg involves a detour via rvalue datums which cause additional work in
form of insertvalue/extractvalue pairs for fat pointer arguments, and an extra
alloca and memcpy for tupled args in rust-call functions.
By merging those three functions into just one that actually covers the whole
process of creating the final argument datums, we can skip all that. Also,
this allows to easily merge in the handling of rust-call functions, allowing to
make create_datum_for_fn_args_under_call_abi obsolete.
cc #26600 -- The insertvalue instructions kicked us off of fast-isel.
This is currently quite buggy in LLVM from what I can tell, so just disable it
entirely. This commit also adds preliminary support, however, to actually
target 32-bit MSVC by making sure the `rust_try_msvc_32.ll` file exists and
wiring up exceptions to `_except_handler3` instead of `__C_specific_handler`
(which doesn't exist on 32-bit).
This library has no shims which are actually needed on Windows now, so translate
that last easy one into Rust and then don't link it at all on Windows.
The current split between create_datums_for_fn_args,
copy_args_to_allocas and store_arg involves a detour via rvalue datums
which cause additional work in form of insertvalue/extractvalue pairs
for fat pointer arguments, and an extra alloca and memcpy for tupled
args in rust-call functions.
By merging those three functions into just one that actually covers the
whole process of creating the final argument datums, we can skip all
that. Also, this allows to easily merge in the handling of rust-call
functions, allowing to make create_datum_for_fn_args_under_call_abi
obsolete.
cc #26600 -- The insertvalue instructions kicked us off of fast-isel.
The tupling only happens for actual closures, same for the untupling.
The only code that actually sees the tupled types is some debugging
output for which it is actually rather confusing to have the types
tupled, because neither the function signature in Rust nor the
function signature for LLVM has them tupled.
This is a simple addition, shouldn't change behavior.
Fixes#26704
I don't know if the coercion for `Rc` is tested, if it is this probably needs the same test with `Weak`.
This doesn't add a test for the main problem in #8640 since it seems that
was already fixed (including a test) in PR https://github.com/rust-lang/rust/pull/19522. This just adds a test
for a program mentioned in the comments that used to erroneously compile.
Closes#8640.
This patch implements the next chunk of flattening out the type checking context. In a series of patches I moved around the necessary state and logic in order to delete the `Typer` and `ClosureTyper` traits. My next goal is to clean the interfaces and start to move the normalization code behind them.
r? @nrc I hope my PR is coherent, doing this too late at night ;)
This was added after Windows 7 SP1, so it's not always available. Instead use
the `SetHandleInformation` function to flag a socket as not inheritable. This is
not atomic with respect to creating new processes, but it mirrors what Unix does
with respect to possibly using the atomic option in the future.
Closes#26543
This doesn't add a test for the main problem in #8640 since it seems that
was already fixed (including a test) in PR #19522. This just adds a test
for a program mentioned in the comments that used to erroneously compile.
Closes#8640.
