bootstrap: don't apply `-Ztls-model=initial-exec` to proc macros #100536

Alexendoo · 2022-08-14T16:14:39Z

Potentially fixes #100530

r? @bjorn3

bjorn3 · 2022-08-14T16:18:49Z

@bors try

bors · 2022-08-14T16:18:57Z

⌛ Trying commit 7ecc8c0e6b3cbebb9568e373def599e8932280d5 with merge b8faa934fa7fcac224925252dcd9884abf34a688...

src/bootstrap/bin/rustc.rs

bjorn3 · 2022-08-14T16:22:16Z

If you have rustup-toolchain-install-master installed (cargo install rustup-toolchain-install-master) you can use rustup-toolchain-install-master -c rustc-dev b8faa934fa7fcac224925252dcd9884abf34a688 to install it once the try build is complete and then cargo +b8faa934fa7fcac224925252dcd9884abf34a688 build to build your test project.

bors · 2022-08-14T17:53:03Z

☀️ Try build successful - checks-actions
Build commit: b8faa934fa7fcac224925252dcd9884abf34a688 (b8faa934fa7fcac224925252dcd9884abf34a688)

Alexendoo · 2022-08-14T18:32:15Z

Ah the try build produced x86 linux assets 😅

Pushed a commit that I believe should make it use aarch64 temporarily

bjorn3 · 2022-08-14T18:48:02Z

@bors try

bors · 2022-08-14T18:48:09Z

⌛ Trying commit 7b941bb9f11cc75b463d5255528b1d9b179890a0 with merge ad757cfdaf165871015454fd840ff1400125fd79...

bors · 2022-08-14T19:29:49Z

☀️ Try build successful - checks-actions
Build commit: ad757cfdaf165871015454fd840ff1400125fd79 (ad757cfdaf165871015454fd840ff1400125fd79)

Alexendoo · 2022-08-14T20:07:57Z

No such luck:

error: /home/alex/.rustup/toolchains/ad757cfdaf165871015454fd840ff1400125fd79/lib/rustlib/aarch64-unknown-linux-gnu/lib/libserde_derive-6dc9fea9ed4dba80.so: cannot allocate memory in static TLS block
 --> src/lib.rs:3:1
  |
3 | extern crate rustc_attr;
  | ^^^^^^^^^^^^^^^^^^^^^^^^

bjorn3 · 2022-08-14T20:21:03Z

Right, -Zdual-proc-macro means that the proc macro is compiled a second time for the target. This time -Ztls-model=initial-exec is passed. Could you add a check that the crate type is not proc-macro before adding the argument? This doesn't catch proc macro dependencies, so at least also the proc-macro2 crate needs to have -Ztls-model=initial-exec disabled. For which you need another conditional.

Alexendoo · 2022-08-16T16:16:13Z

Is that what you meant?

My comment is lacking, I don't know enough about proc macros to explain why it's in target.is_some()

bjorn3 · 2022-08-16T17:01:12Z

Is that what you meant?

Yes

@bors try

bors · 2022-08-16T17:01:20Z

⌛ Trying commit de81d0661c0278a95fde22aa0a5b9f0eac1bb3e9 with merge 5618bbd2f9cff002b70877eb50368991de5e4ab7...

bors · 2022-08-16T17:36:26Z

☀️ Try build successful - checks-actions
Build commit: 5618bbd2f9cff002b70877eb50368991de5e4ab7 (5618bbd2f9cff002b70877eb50368991de5e4ab7)

Alexendoo · 2022-08-16T18:23:18Z

There's progress, before the following crates would give the error:

rustc_ast_lowering
rustc_ast_passes
rustc_attr
rustc_borrowck
rustc_builtin_macros
rustc_codegen_llvm
rustc_codegen_ssa
rustc_const_eval
rustc_driver
rustc_errors
rustc_expand
rustc_hir_pretty
rustc_hir
rustc_incremental
rustc_infer
rustc_interface
rustc_lint_defs
rustc_lint
rustc_metadata
rustc_middle
rustc_mir_build
rustc_mir_dataflow
rustc_mir_transform
rustc_monomorphize
rustc_parse
rustc_passes
rustc_plugin_impl
rustc_privacy
rustc_query_impl
rustc_query_system
rustc_resolve
rustc_save_analysis
rustc_session
rustc_smir
rustc_symbol_mangling
rustc_target
rustc_trait_selection
rustc_traits
rustc_transmute
rustc_ty_utils
rustc_typeck

On 5618bbd2f9cff002b70877eb50368991de5e4ab7 there are fewer:

rustc_ast_lowering
rustc_borrowck
rustc_codegen_llvm
rustc_codegen_ssa
rustc_const_eval
rustc_driver
rustc_incremental
rustc_infer
rustc_interface
rustc_lint
rustc_metadata
rustc_middle
rustc_mir_build
rustc_mir_dataflow
rustc_mir_transform
rustc_monomorphize
rustc_passes
rustc_plugin_impl
rustc_privacy
rustc_query_impl
rustc_resolve
rustc_save_analysis
rustc_smir
rustc_symbol_mangling
rustc_trait_selection
rustc_traits
rustc_transmute
rustc_ty_utils
rustc_typeck

bjorn3 · 2022-08-16T18:41:29Z

What is the exact error in those cases?

Alexendoo · 2022-08-16T20:04:28Z

error: /home/alex/.rustup/toolchains/5618bbd2f9cff002b70877eb50368991de5e4ab7/lib/rustlib/aarch64-unknown-linux-gnu/lib/libchalk_derive-8ea0a51673aa1739.so: cannot allocate memory in static TLS block
 --> src/lib.rs:3:1
  |
3 | extern crate rustc_ast_lowering;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

(same error for all of them)

bjorn3 · 2022-08-16T20:30:15Z

chalk_derive depends on quote, syn and synstructure. I don't know which one is responsible, but adding all of them as exceptions just like proc-macro2 would work I think.

bjorn3 · 2022-08-16T20:37:56Z

@bors try

bors · 2022-08-16T20:38:04Z

⌛ Trying commit fd0327d0194cb9a6150f814ea84ec9973faee050 with merge d65f8b66932795e8cc8e3f099902dc2ad9813af5...

bors · 2022-08-16T21:12:39Z

☀️ Try build successful - checks-actions
Build commit: d65f8b66932795e8cc8e3f099902dc2ad9813af5 (d65f8b66932795e8cc8e3f099902dc2ad9813af5)

Alexendoo · 2022-08-16T21:25:58Z

Nice, that one compiled successfully! Thanks for walking me through it

rebased + removed the ci try change

bjorn3 · 2022-08-17T09:33:31Z

LGTM, but given that I suggested this fix, I'm going to defer final review to someone else.

r? @Mark-Simulacrum You also reviewed #78201. Would you mind taking a look?

Mark-Simulacrum · 2022-08-17T10:52:34Z

src/bootstrap/bin/rustc.rs

+        // issue https://github.com/rust-lang/rust/issues/100530
+        if env::var("RUSTC_TLS_MODEL_INITIAL_EXEC").is_ok()
+            && arg("--crate-type") != Some("proc-macro")
+            && !matches!(crate_name, Some("proc_macro2" | "quote" | "syn" | "synstructure"))


Is there a test or something else we can add that validates this list is enough? For example, I'm thinking that maybe our invocations of cargo metadata can help here?

I don't think this is something we should do in rustc.rs, probably too much overhead, but some kind of out of band check seems like a good idea to me.

I guess the actual set is something like proc macros dep and contains TLS symbols, or so?

For example, rustc_macros depends on multiple other crates:

https://github.com/rust-lang/rust/blob/master/compiler/rustc_macros/Cargo.toml#L10

I guess the actual set is something like proc macros dep and contains TLS symbols, or so?

Yes, although a blanket include of all proc macro deps would be correct though. It may just cause a perf regression.

I think we should try it; my guess is that TLS access for these crates isn't hot (even at runtime if they're pulled in there).

Or we can go a different direction and try to test this, but it sounds like doing that isn't trivial?

I think checking all proc macro dylibs shipped with rustc-dev for the R_X86_64_TPOFF64 relocation kind (on x86_64, aarch64 has a different relocation name) would suffice. R_X86_64_DTPOFF64 is the only TLS relocation kind that is used for the global dynamic tls model (the most general tls model) I think.

The difference before/after appears to be R_AARCH64_TLS_TPREL64

Is there a nice way to get a list of the proc macro dylibs in a run-make-fulldeps test? (or a better way to test for that)

Mark-Simulacrum · 2022-08-20T15:50:47Z

@bors r+ rollup=never

I think let's land this for now, we'll keep #92976 open (I'll leave a comment there) that we should add testing for this since the current solution is easy to regress on in the future.

bors · 2022-08-20T15:50:49Z

📌 Commit 23abd59 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

bors · 2022-08-21T01:34:08Z

⌛ Testing commit 23abd59 with merge f2858b5...

bors · 2022-08-21T04:21:00Z

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing f2858b5 to master...

rust-timer · 2022-08-21T05:35:55Z

Finished benchmarking commit (f2858b5): comparison url.

Instruction count

Primary benchmarks: no relevant changes found
Secondary benchmarks: ✅ relevant improvements found

	mean¹	max	count²
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.3%	-0.3%	2
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results

Primary benchmarks: no relevant changes found
Secondary benchmarks: mixed results

	mean¹	max	count²
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.8%	1.8%	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.7%	-2.7%	1
All ❌✅ (primary)	-	-	0

Cycles

Results

Primary benchmarks: mixed results
Secondary benchmarks: no relevant changes found

	mean¹	max	count²
Regressions ❌ (primary)	2.9%	3.2%	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.8%	-1.8%	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.3%	3.2%	3

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

the arithmetic mean of the percent change ↩ ↩² ↩³
number of relevant changes ↩ ↩² ↩³

rustbot added the T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) label Aug 14, 2022

rust-highfive assigned bjorn3 Aug 14, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 14, 2022

bjorn3 reviewed Aug 14, 2022

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rustbot added the T-infra Relevant to the infrastructure team, which will review and decide on the PR/issue. label Aug 14, 2022

bootstrap: don't apply -Ztls-model=initial-exec to proc macros

23abd59

Alexendoo force-pushed the bootstrap-tls-model branch from fd0327d to 23abd59 Compare August 16, 2022 21:22

Alexendoo changed the title ~~bootstrap: limit -Ztls-model=initial-exec to non-host crates~~ bootstrap: don't apply -Ztls-model=initial-exec to proc macros Aug 16, 2022

workingjubilee added the O-AArch64 Armv8-A or later processors in AArch64 mode label Aug 17, 2022

rust-highfive assigned Mark-Simulacrum and unassigned bjorn3 Aug 17, 2022

Mark-Simulacrum reviewed Aug 17, 2022

View reviewed changes

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 Aug 20, 2022

Mark-Simulacrum mentioned this pull request Aug 20, 2022

Rustbuild compiles proc macros with -Ztls-model=inital-exec when cross-compiling #92976

Open

bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 21, 2022

bors merged commit f2858b5 into rust-lang:master Aug 21, 2022

rustbot added this to the 1.65.0 milestone Aug 21, 2022

Alexendoo deleted the bootstrap-tls-model branch August 21, 2022 10:24

bootstrap: don't apply -Ztls-model=initial-exec to proc macros #100536

bootstrap: don't apply -Ztls-model=initial-exec to proc macros #100536

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Mark-Simulacrum commented Aug 20, 2022

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rust-timer commented Aug 21, 2022

Footnotes

bootstrap: don't apply `-Ztls-model=initial-exec` to proc macros #100536

bootstrap: don't apply `-Ztls-model=initial-exec` to proc macros #100536

bjorn3 commented Aug 14, 2022 •

edited

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Alexendoo commented Aug 14, 2022 •

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Alexendoo commented Aug 16, 2022 •

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