Reinstate preloading of some dll imports #100984
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
rustbot
added
the
T-libs
rust-highfive
added
the
S-waiting-on-review
ChrisDenton
force-pushed
the
reinstate-init
branch
from
5fb3f79 to
c44d57c
Compare
Mark-Simulacrum
added
S-waiting-on-author
|
I've updated the comments to hopefully be a bit more accurate. @rustbot ready |
rustbot
added
S-waiting-on-review
|
r=me with commits squashed. |
Mark-Simulacrum
added
S-waiting-on-author
ChrisDenton
force-pushed
the
reinstate-init
branch
from
f2a08f7 to
7bb47a6
Compare
|
@bors r=Mark-Simulacrum |
bors
added
S-waiting-on-bors
matthiaskrgr
added a commit
to matthiaskrgr/rust
that referenced
this pull request
Aug 31, 2022
…-Simulacrum Reinstate preloading of some dll imports I've now come around to the conclusion that there is a justification for pre-loading the synchronization functions `WaitOnAddress` and `WakeByAddressSingle`. I've found this to have a particularly impact in testing frameworks that may have short lived processes which immediately spawn lots of threads. Also, because pre-main initializers imply a single-threaded environment, we can switch back to using relaxed atomics which might be a minor perf improvement on some platforms (though I doubt it's particularly notable). r? `@Mark-Simulacrum` and sorry for the churn here. For convenience I'll summarise previous issues with preloading and the solutions that are included in this PR (if any): **Issue:** User pre-main initializers may be run before std's **Solution:** The std now uses initializers that are guaranteed to run earlier than the old initializers. A note is also added that users should not copy std's behaviour if they want to ensure they run their initializers after std. **Issue:** Miri does not understand pre-main initializers. **Solution:** For miri only, run the function loading lazily instead. **Issue:** We should ideally use `LoadLibrary` to get "api-ms-win-core-synch-l1-2-0". Only "ntdll" and "kernel32" are guaranteed to always be loaded. **Solution:** None. We can't use `LoadLibrary` pre-main. However, in the past `GetModuleHandle` has always worked in practice so this should hopefully not be a problem. If/when Windows 7 support is dropped, we can finally remove all this for good and just use normal imports.
This was referenced Aug 31, 2022
bors
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Aug 31, 2022
…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#100970 (Allow deriving multipart suggestions) - rust-lang#100984 (Reinstate preloading of some dll imports) - rust-lang#101011 (Use getentropy when possible on all Apple platforms) - rust-lang#101025 (Add tier-3 support for powerpc64 and riscv64 openbsd) - rust-lang#101049 (Remove span fatal from ast lowering) - rust-lang#101100 (Make call suggestions more general and more accurate) - rust-lang#101171 (Fix UB from misalignment and provenance widening in `std::sys::windows`) - rust-lang#101185 (Tweak `WellFormedLoc`s a bit) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
I've now come around to the conclusion that there is a justification for pre-loading the synchronization functions
WaitOnAddressandWakeByAddressSingle. I've found this to have a particularly impact in testing frameworks that may have short lived processes which immediately spawn lots of threads.Also, because pre-main initializers imply a single-threaded environment, we can switch back to using relaxed atomics which might be a minor perf improvement on some platforms (though I doubt it's particularly notable).
r? @Mark-Simulacrum and sorry for the churn here.
For convenience I'll summarise previous issues with preloading and the solutions that are included in this PR (if any):
Issue: User pre-main initializers may be run before std's
Solution: The std now uses initializers that are guaranteed to run earlier than the old initializers. A note is also added that users should not copy std's behaviour if they want to ensure they run their initializers after std.
Issue: Miri does not understand pre-main initializers.
Solution: For miri only, run the function loading lazily instead.
Issue: We should ideally use
LoadLibraryto get "api-ms-win-core-synch-l1-2-0". Only "ntdll" and "kernel32" are guaranteed to always be loaded.Solution: None. We can't use
LoadLibrarypre-main. However, in the pastGetModuleHandlehas always worked in practice so this should hopefully not be a problem.If/when Windows 7 support is dropped, we can finally remove all this for good and just use normal imports.