Bump minimal supported LLVM version to 9 #78848

DevJPM · 2020-11-07T20:06:24Z

This bumps the minimal tested llvm version to 9.
This should enable supporting newer LLVM features (and CPU extensions).

This was motived by #78361 having to drop features because of LLVM 8 not supporting certain CPU extensions yet.
This was declared relatively uncontroversial on Zulip.

Paging @eddyb because there was a comment in the dockerfile describing a hack (which I don't quite understand) which was also blocked by not having LLVM 9.

rust-highfive · 2020-11-07T20:06:27Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @pietroalbini (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

nikic · 2020-11-07T20:52:26Z

This builder always tests the lowest supported version of LLVM -- if you want to bump the tested version, you actually need to drop support for LLVM 8.

In particular you need to adjust

rust/src/bootstrap/native.rs

Line 334 in b2d115f

fn check_llvm_version(builder: &Builder<'_>, llvm_config: &Path) {

, and then grep for LLVM_VERSION_GE, LLVM_VERSION_LT, get_major_version, min-llvm-version to find places where compatibility code can be dropped.

DevJPM · 2020-11-07T22:31:45Z

@nikic Thank you very much for these suggestions. They have been exactly what I've been looking for - but failed to find amidst the size of Rust.

The latest commit does indeed grep for these constants and drops compatibility code whereever possible and sensible.

pietroalbini · 2020-11-09T11:13:52Z

The CI changes look good! r? @nikic for the rest.

nikic · 2020-11-10T17:57:46Z

compiler/rustc_codegen_llvm/src/attributes.rs

-            if feature == new {
-                return old;
-            }
+    for &(old, new) in LLVM9_FEATURE_CHANGES {


It's okay to just drop this code entirely. In later LLVM upgrades we decided that we should not do bidirectional emulation (there are no stability guarantees for custom target definitions).

nikic · 2020-11-10T23:06:33Z

@bors r+

bors · 2020-11-10T23:06:34Z

📌 Commit 41387913d38dec9de4e7ec48498357cb432ffcd3 has been approved by nikic

DevJPM · 2020-11-12T09:34:02Z

Sorry to anyone who might have been notified by my failed attempt at fixing the merge conflict indicated by GitHub

This bumps the minimal tested llvm version to 9. This should enable supporting newer LLVM features (and CPU extensions).

apparently llvm-8-tools already had llvm-8-dev as a dependency which was removed in llvm-9-tools, so we need to explicitly pull llvm-9-dev to make a build

This commit grepped for LLVM_VERSION_GE, LLVM_VERSION_LT, get_major_version and min-llvm-version and statically evaluated every expression possible (and sensible) assuming that the LLVM version is >=9 now

…ersion The function was only used in LLVM 8 compatibility code and was found and flagged by dead code detection and now removed.

as requested in the review and argued that this is only consistent with later LLVM upgrades

DevJPM · 2020-11-12T13:54:19Z

The update was due to a merge conflict in attribute.rs where my changes forced a re-format to one-line and another change removed one intermediate value

DevJPM · 2020-11-14T15:32:36Z

So, it appears that after the approval of this PR a merge conflict got merged into master - which I fixed - but now appears that bors has no intention of merging this PR anymore without another approval? (Hoping that I read this page correctly)

So, can I ask for an approval of the conflict-free PR? @nikic ? (Hoping that I understand the workflows around here correctly)

nikic · 2020-11-14T15:34:50Z

You got that right.

@bors r+

bors · 2020-11-14T15:34:52Z

📌 Commit 86193ca has been approved by nikic

Rollup of 15 pull requests Successful merges: - rust-lang#78352 (Do not call `unwrap` with `signatures` option enabled) - rust-lang#78590 (refactor: removing alloc::collections::vec_deque ignore-tidy-filelength) - rust-lang#78848 (Bump minimal supported LLVM version to 9) - rust-lang#78856 (Explicitly checking for or-pattern before test) - rust-lang#78948 (test: add `()=()=()=...` to weird-exprs.rs) - rust-lang#78962 (Add a test for r# identifiers) - rust-lang#78963 (Added some unit tests as requested) - rust-lang#78966 (Never inline C variadics, cold functions, functions with incompatible attributes ...) - rust-lang#78968 (Include llvm-as in llvm-tools-preview component) - rust-lang#78969 (Normalize function type during validation) - rust-lang#78980 (Fix rustc_ast_pretty print_qpath resulting in invalid macro input) - rust-lang#78986 (Avoid installing external LLVM dylibs) - rust-lang#78988 (Fix an intrinsic invocation on threaded wasm) - rust-lang#78993 (rustc_target: Fix dash vs underscore mismatches in option names) - rust-lang#79013 (Clean up outdated `use_once_payload` pretty printer comment) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

With rust-lang#78848 merged, the minimum supported LLVM version is now 9 which means we can actually use the target features introduced in LLVM 9

Remove Hacks and Fixmes from PR CI's LLVM-9 Container Now with LLVM 9 being the minimum supported version (thanks to rust-lang#78848 ), we can finally remove the hacks in the dockerfile. This wasn't in the main PR bumping the version as I didn't quite understand what's going on and needed here. Relevant issues and PRs: - Issue rust-lang#69823 - PR rust-lang#70989 I hope I actually adressed things correctly here?

Pkgsrc changes: * Adjust patches, convert tabs to spaces so that tests pass. * Remove patches which are no longer needed (upstream changed) * Minor adjustments for SunOS, e.g. disable stack probes. * Adjust cargo checksum patching accordingly. * Remove commented-out use of PATCHELF on NetBSD, which doesn't work anyway... Upstream changes: Version 1.49.0 (2020-12-31) ============================ Language ----------------------- - [Unions can now implement `Drop`, and you can now have a field in a union with `ManuallyDrop<T>`.][77547] - [You can now cast uninhabited enums to integers.][76199] - [You can now bind by reference and by move in patterns.][76119] This allows you to selectively borrow individual components of a type. E.g. ```rust #[derive(Debug)] struct Person { name: String, age: u8, } let person = Person { name: String::from("Alice"), age: 20, }; // `name` is moved out of person, but `age` is referenced. let Person { name, ref age } = person; println!("{} {}", name, age); ``` Compiler ----------------------- - [Added tier 1\* support for `aarch64-unknown-linux-gnu`.][78228] - [Added tier 2 support for `aarch64-apple-darwin`.][75991] - [Added tier 2 support for `aarch64-pc-windows-msvc`.][75914] - [Added tier 3 support for `mipsel-unknown-none`.][78676] - [Raised the minimum supported LLVM version to LLVM 9.][78848] - [Output from threads spawned in tests is now captured.][78227] - [Change os and vendor values to "none" and "unknown" for some targets][78951] \* Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries ----------------------- - [`RangeInclusive` now checks for exhaustion when calling `contains` and indexing.][78109] - [`ToString::to_string` now no longer shrinks the internal buffer in the default implementation.][77997] - [`ops::{Index, IndexMut}` are now implemented for fixed sized arrays of any length.][74989] Stabilized APIs --------------- - [`slice::select_nth_unstable`] - [`slice::select_nth_unstable_by`] - [`slice::select_nth_unstable_by_key`] The following previously stable methods are now `const`. - [`Poll::is_ready`] - [`Poll::is_pending`] Cargo ----------------------- - [Building a crate with `cargo-package` should now be independently reproducible.][cargo/8864] - [`cargo-tree` now marks proc-macro crates.][cargo/8765] - [Added `CARGO_PRIMARY_PACKAGE` build-time environment variable.] [cargo/8758] This variable will be set if the crate being built is one the user selected to build, either with `-p` or through defaults. - [You can now use glob patterns when specifying packages & targets.][cargo/8752] Compatibility Notes ------------------- - [Demoted `i686-unknown-freebsd` from host tier 2 to target tier 2 support.][78746] - [Macros that end with a semi-colon are now treated as statements even if they expand to nothing.][78376] - [Rustc will now check for the validity of some built-in attributes on enum variants.][77015] Previously such invalid or unused attributes could be ignored. - Leading whitespace is stripped more uniformly in documentation comments, which may change behavior. You read [this post about the changes][rustdoc-ws-post] for more details. - [Trait bounds are no longer inferred for associated types.][79904] Internal Only ------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. - [rustc's internal crates are now compiled using the `initial-exec` Thread Local Storage model.][78201] - [Calculate visibilities once in resolve.][78077] - [Added `system` to the `llvm-libunwind` bootstrap config option.][77703] - [Added `--color` for configuring terminal color support to bootstrap.][79004] [75991]: rust-lang/rust#75991 [78951]: rust-lang/rust#78951 [78848]: rust-lang/rust#78848 [78746]: rust-lang/rust#78746 [78376]: rust-lang/rust#78376 [78228]: rust-lang/rust#78228 [78227]: rust-lang/rust#78227 [78201]: rust-lang/rust#78201 [78109]: rust-lang/rust#78109 [78077]: rust-lang/rust#78077 [77997]: rust-lang/rust#77997 [77703]: rust-lang/rust#77703 [77547]: rust-lang/rust#77547 [77015]: rust-lang/rust#77015 [76199]: rust-lang/rust#76199 [76119]: rust-lang/rust#76119 [75914]: rust-lang/rust#75914 [74989]: rust-lang/rust#74989 [79004]: rust-lang/rust#79004 [78676]: rust-lang/rust#78676 [79904]: rust-lang/rust#79904 [cargo/8864]: rust-lang/cargo#8864 [cargo/8765]: rust-lang/cargo#8765 [cargo/8758]: rust-lang/cargo#8758 [cargo/8752]: rust-lang/cargo#8752 [`slice::select_nth_unstable`]: https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.select_nth_unstable [`slice::select_nth_unstable_by`]: https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.select_nth_unstable_by [`slice::select_nth_unstable_by_key`]: https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.select_nth_unstable_by_key [`hint::spin_loop`]: https://doc.rust-lang.org/stable/std/hint/fn.spin_loop.html [`Poll::is_ready`]: https://doc.rust-lang.org/stable/std/task/enum.Poll.html#method.is_ready [`Poll::is_pending`]: https://doc.rust-lang.org/stable/std/task/enum.Poll.html#method.is_pending [rustdoc-ws-post]: https://blog.guillaume-gomez.fr/articles/2020-11-11+New+doc+comment+handling+in+rustdoc

rust-highfive assigned pietroalbini Nov 7, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 7, 2020

DevJPM changed the title ~~Bumped minimal tested LLVM version to 9~~ Bump minimal tested LLVM version to 9 Nov 7, 2020

est31 mentioned this pull request Nov 7, 2020

Add an unstable --json=unused-externs flag to print unused externs #73945

Merged

DevJPM changed the title ~~Bump minimal tested LLVM version to 9~~ Bump supported LLVM version to 9 Nov 7, 2020

DevJPM changed the title ~~Bump supported LLVM version to 9~~ Bump minimal supported LLVM version to 9 Nov 7, 2020

rust-highfive assigned nikic and unassigned pietroalbini Nov 9, 2020

cuviper added the relnotes Marks issues that should be documented in the release notes of the next release. label Nov 9, 2020

cuviper approved these changes Nov 9, 2020

View reviewed changes

nikic reviewed Nov 10, 2020

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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 Nov 10, 2020

DevJPM force-pushed the ci-llvm-9 branch from bf2f091 to 4138791 Compare November 12, 2020 09:32

DevJPM added 7 commits November 12, 2020 14:39

Bumped minimal tested LLVM version to 9

f8a32e9

This bumps the minimal tested llvm version to 9. This should enable supporting newer LLVM features (and CPU extensions).

explicitly add llvm-9-dev in dockerfile

6323565

apparently llvm-8-tools already had llvm-8-dev as a dependency which was removed in llvm-9-tools, so we need to explicitly pull llvm-9-dev to make a build

Bump the minimal supported LLVM version in the bootstrapping code to 9.0

6830f1c

fully exploited the dropped support of LLVM 8

b51bcc7

This commit grepped for LLVM_VERSION_GE, LLVM_VERSION_LT, get_major_version and min-llvm-version and statically evaluated every expression possible (and sensible) assuming that the LLVM version is >=9 now

Removed an unused function now that LLVM 9 is the minimal supported v…

8236830

…ersion The function was only used in LLVM 8 compatibility code and was found and flagged by dead code detection and now removed.

Dropped Support for Bidirectional Custom Target Definition Emulation

7e443c4

as requested in the review and argued that this is only consistent with later LLVM upgrades

fixed a re-format due to removed chain call

86193ca

DevJPM force-pushed the ci-llvm-9 branch from 4138791 to 86193ca Compare November 12, 2020 13:52

jonas-schievink mentioned this pull request Nov 14, 2020

Rollup of 26 pull requests #79053

Closed

jonas-schievink mentioned this pull request Nov 14, 2020

Rollup of 25 pull requests #79056

Closed

jonas-schievink mentioned this pull request Nov 14, 2020

Rollup of 24 pull requests #79057

Closed

Dylan-DPC-zz mentioned this pull request Nov 15, 2020

Rollup of 15 pull requests #79065

Merged

bors merged commit ae7020f into rust-lang:master Nov 15, 2020

rustbot added this to the 1.50.0 milestone Nov 15, 2020

DevJPM deleted the ci-llvm-9 branch November 15, 2020 10:42

This was referenced Nov 15, 2020

Remove Hacks and Fixmes from PR CI's LLVM-9 Container #79068

Merged

Updated the list of white-listed target features for x86 #78361

Merged

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Bump minimal supported LLVM version to 9 #78848

Bump minimal supported LLVM version to 9 #78848

DevJPM commented Nov 7, 2020

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Bump minimal supported LLVM version to 9 #78848

Bump minimal supported LLVM version to 9 #78848

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