Support TLS access into dylibs on Windows #108089

Zoxc · 2023-02-15T16:36:58Z

This allows access to #[thread_local] in upstream dylibs on Windows by introducing a MIR shim to return the address of the thread local. Accesses that go into an upstream dylib will call the MIR shim to get the address of it.

convert_tls_rvalues is introduced in rustc_codegen_ssa which rewrites MIR TLS accesses to dummy calls which are replaced with calls to the MIR shims when the dummy calls are lowered to backend calls.

A new dll_tls_export target option enables this behavior with a false value which is set for Windows platforms.

This fixes #84933.

rustbot · 2023-02-15T16:37:06Z

r? @Nilstrieb

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rustbot · 2023-02-15T16:37:10Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

These commits modify compiler targets.
(See the Target Tier Policy.)

Some changes occurred to the CTFE / Miri engine

cc @rust-lang/miri

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

Examples of T-libs-api changes:

Stabilizing library features
Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
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Noratrieb

I took a look over it, looks great, thanks for finally solving this!

I am not familiar enough with this sort of code to approve it, so I'll hand it off to someone else.
r? @wesleywiser, I hope you can review this :D, assigning you directly since compiler includes plenty of people who wouldn't review this code either

ccing the people involved in #101368, @thomcc @eddyb @ChrisDenton

Noratrieb · 2023-02-15T18:45:16Z

compiler/rustc_mir_transform/src/shim.rs

+        is_cleanup: false,
+    });
+
+    let ret_ty = Rvalue::ThreadLocalRef(def_id).ty(&IndexVec::new(), tcx);


Could you factor out the "type of tls ref" logic into a helper function somewhere and use it here (and in the other places where you need it, including the impl of Rvalue::ty)?

I created a tcx.thread_local_ptr_ty method for that. It's suspiciously similar to tcx.static_ptr_ty which normalizes and erases regions. It's possible thread_local_ptr_ty should call that.

compiler/rustc_mir_transform/src/shim.rs

compiler/rustc_codegen_ssa/src/mir/mod.rs

compiler/rustc_middle/src/ty/instance.rs

compiler/rustc_codegen_ssa/src/mir/mod.rs

compiler/rustc_monomorphize/src/partitioning/default.rs

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

compiler/rustc_codegen_ssa/src/mir/mod.rs

rustbot · 2023-02-19T14:59:25Z

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

Zoxc · 2023-02-19T15:11:23Z

I've added untested cranelift support. I tried to test using rust.codegen-backends = ["cranelift"], but I ran into a std linking error:

libpanic_unwind-12135c8a369c0c33.rlib(panic_unwind-12135c8a369c0c33.panic_unwind.b580d029-cgu.1.rcgu.o) : error LNK2001: unresolved external symbol ☺??_7type_info@@6B@
F:\Rust\rust\build\x86_64-pc-windows-msvc\stage1-std\x86_64-pc-windows-msvc\release\deps\std-e639197673660265.dll : fatal error LNK1120: 1 unresolved externals

bjorn3 · 2023-02-19T15:15:30Z

On Windows panic_unwind imports \x01??_7type_info@@6B@. The \x01 here tells LLVM to not do any symbol mangling. cg_clif doesn't implement this yet: https://github.com/bjorn3/rustc_codegen_cranelift/issues/1332 It should work fine on Linux and macOS and it may also work if you remove panic-unwind from

rust/src/bootstrap/lib.rs

Line 722 in eebdfb5

let mut features = " panic-unwind".to_string();

, but I haven't tested that.

bors · 2023-02-22T22:11:20Z

☔ The latest upstream changes (presumably #108340) made this pull request unmergeable. Please resolve the merge conflicts.

wesleywiser · 2023-03-06T16:58:48Z

Thanks @Zoxc for fixing this! The implementation chosen looks good to me.

@bors r+

bors · 2023-03-06T16:58:51Z

📌 Commit 6c9d750 has been approved by wesleywiser

It is now in the queue for this repository.

Support TLS access into dylibs on Windows This allows access to `#[thread_local]` in upstream dylibs on Windows by introducing a MIR shim to return the address of the thread local. Accesses that go into an upstream dylib will call the MIR shim to get the address of it. `convert_tls_rvalues` is introduced in `rustc_codegen_ssa` which rewrites MIR TLS accesses to dummy calls which are replaced with calls to the MIR shims when the dummy calls are lowered to backend calls. A new `dll_tls_export` target option enables this behavior with a `false` value which is set for Windows platforms. This fixes rust-lang#84933.

bjorn3 · 2023-03-29T09:37:37Z

@bors r+

bors · 2023-03-29T09:37:40Z

📌 Commit 3019a34 has been approved by bjorn3

It is now in the queue for this repository.

bors · 2023-03-29T12:20:27Z

⌛ Testing commit 3019a34 with merge 55acf51dcaf91ffa64f7a2aea4fc0615720b28b9...

bors · 2023-03-29T12:43:55Z

💔 Test failed - checks-actions

bjorn3 · 2023-03-29T13:09:39Z

@bors r+

bors · 2023-03-29T13:09:41Z

📌 Commit d499bbb has been approved by bjorn3

It is now in the queue for this repository.

bors · 2023-03-29T16:20:41Z

⌛ Testing commit d499bbb with merge f98598c...

bors · 2023-03-29T19:18:37Z

☀️ Test successful - checks-actions
Approved by: bjorn3
Pushing f98598c to master...

rust-timer · 2023-03-29T20:36:24Z

Finished benchmarking commit (f98598c): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

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	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	5.5%	[5.5%, 5.5%]	1
Improvements ✅ (primary)	-2.5%	[-2.5%, -2.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.5%	[-2.5%, -2.5%]	1

Cycles

This benchmark run did not return any relevant results for this metric.

Workaround rust-lang#109797 on windows-gnu The addition of `#[inline]` here in rust-lang#108089 caused an unrelated linking issue (rust-lang#109797). This PR removes this attribute again on Windows to avoid regressions.

Workaround #109797 on windows-gnu The addition of `#[inline]` here in rust-lang/rust#108089 caused an unrelated linking issue (rust-lang/rust#109797). This PR removes this attribute again on Windows to avoid regressions.

rustbot assigned Noratrieb Feb 15, 2023

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Feb 15, 2023

Noratrieb reviewed Feb 15, 2023

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rustbot assigned wesleywiser and unassigned Noratrieb Feb 15, 2023

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Zoxc force-pushed the windows-tls branch from 2909c24 to 8c08d4a Compare February 19, 2023 00:45

Zoxc force-pushed the windows-tls branch from 544635f to 6c9d750 Compare February 22, 2023 22:43

wesleywiser approved these changes Mar 6, 2023

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 6, 2023

matthiaskrgr mentioned this pull request Mar 8, 2023

Rollup of 8 pull requests #108921

Closed

matthiaskrgr mentioned this pull request Mar 9, 2023

Rollup of 7 pull requests #108935

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Use #[inline] on Windows for thread local access

3019a34

Zoxc force-pushed the windows-tls branch from d3afbb6 to 3019a34 Compare March 29, 2023 07:10

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 29, 2023

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Mar 29, 2023

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Use #[cfg(target_thread_local)] on items

d499bbb

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 29, 2023

bors added the merged-by-bors This PR was explicitly merged by bors. label Mar 29, 2023

bors merged commit f98598c into rust-lang:master Mar 29, 2023

rustbot added this to the 1.70.0 milestone Mar 29, 2023

bors mentioned this pull request Mar 29, 2023

Run various queries from other queries instead of explicitly in phases #108118

Merged

Zoxc deleted the windows-tls branch March 30, 2023 01:25

ehuss mentioned this pull request Mar 31, 2023

windows-gnu thin-lto test linking error regression #109797

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Zoxc mentioned this pull request Mar 31, 2023

Workaround #109797 on windows-gnu #109806

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fmease mentioned this pull request Apr 12, 2024

Re-enable has_thread_local for i686-msvc #123257

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Support TLS access into dylibs on Windows #108089

Support TLS access into dylibs on Windows #108089

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Support TLS access into dylibs on Windows #108089

Support TLS access into dylibs on Windows #108089

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Overall result: no relevant changes - no action needed

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