Add initial support for m68k #88321

glaubitz · 2021-08-25T08:05:25Z

This patch series adds initial support for m68k making use of the new M68k
backend introduced with LLVM-13. Additional changes will be needed to be
able to actually use the backend for this target.

rust-highfive · 2021-08-25T08:05:28Z

r? @wesleywiser

(rust-highfive has picked a reviewer for you, use r? to override)

rust-highfive · 2021-08-25T08:05:28Z

⚠️ Warning ⚠️

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

glaubitz · 2021-08-25T08:05:50Z

CC @ricky26

compiler/rustc_llvm/src/lib.rs

glaubitz · 2021-08-25T08:27:20Z

Hmm, that LLVM build error on (x86_64-gnu-tools, 1, ubuntu-latest-xl) is odd.

@ricky26 Any idea?

glaubitz · 2021-08-25T08:48:50Z

Hmm, odd. My local builds work fine with gcc-7.5 on openSUSE 15.3. I'll try Debian Bullseye with gcc-10.

ricky26 · 2021-08-25T08:56:04Z

It looks like it's due to Kind being both an enum class type & a field in that struct. Must be a compiler version thing though, since it does compile fine over here (and I'm pretty sure at least one of the LLVM bots builds the M68k target).

src/tools/build-manifest/src/main.rs

glaubitz · 2021-08-25T17:29:54Z

@ricky26 This looks eerily similar to this issue: intel/gazebo-sitl#46

And it might be this particular bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60994

I'll research whether the gcc in Ubuntu 18.04 LTS is still affected by the bug.

jrtc27 · 2021-08-25T18:17:29Z

compiler/rustc_target/src/spec/m68k_unknown_linux_gnu.rs

+    Target {
+        llvm_target: "m68k-unknown-linux-gnu".to_string(),
+        pointer_width: 32,
+        data_layout: "E-m:e-p:32:32-i8:8:8-i16:16:16-i32:32:32-n8:16:32-a:0:32-S16".to_string(),


This data layout is wrong, the m68k ABI in use doesn't have 32-bit-aligned ints etc

OK, this should be it then?

glaubitz@node54:/data/home/glaubitz/llvm-project/build> clang -S -x c /dev/null -o - -emit-llvm --target=m68k-linux-gnu | grep datalayout target datalayout = "E-m:e-p:32:32-i8:8:8-i16:16:16-i32:16:32-n8:16:32-a:0:16-S16" glaubitz@node54:/data/home/glaubitz/llvm-project/build>

p:32:32 still looks wrong, _Alignof(void *) is 2 not 4 so it should be p:32:16:32 just like i32, so that needs fixing in LLVM

OK, we'll have to report that to the LLVM bug tracker then.

Any idea regarding the build failure?

Repeating what I said on IRC here so others can see:
[20:06:26] -- The C compiler identification is GNU 5.4.0
[20:06:31] ditto CXX
[20:08:14] the job is using a 16.04 environment
[20:09:23] the host is 18.04 but the builds are done in docker containers
[20:12:31] (by running docker build on https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile)

So, yes, this looks like that GCC bug, and I suggest renaming the enum type itself to KindTy in the M68k AsmParser like is used in the RISCV one.

Repeating what I said on IRC here so others can see:
[20:06:26] -- The C compiler identification is GNU 5.4.0
[20:06:31] ditto CXX
[20:08:14] the job is using a 16.04 environment
[20:09:23] the host is 18.04 but the builds are done in docker containers
[20:12:31] (by running docker build on https://github.com/rust-lang/rust/blob/master/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile)

Ah, I was looking everywhere in the build log but I couldn't find the reference. But yeah, the Dockerfile wholly explains why we're on such an old compiler version.

So, yes, this looks like that GCC bug, and I suggest renaming the enum type itself to KindTy in the M68k AsmParser like is used in the RISCV one.

Would that work-around the issue? I assume yes when looking at what @ricky26 said.

ricky26 · 2021-08-25T20:13:06Z

I've put a prospective patch in to LLVM: https://reviews.llvm.org/D108723.

Even if that lands in main soon, I don't know what the timeline would be for it getting into a release. (I'd be surprised if it qualified to go into the release branch.)

jrtc27 · 2021-08-25T20:22:32Z

I've put a prospective patch in to LLVM: https://reviews.llvm.org/D108723.

Even if that lands in main soon, I don't know what the timeline would be for it getting into a release. (I'd be surprised if it qualified to go into the release branch.)

Rust uses its own fork of LLVM, https://github.com/rust-lang/llvm-project, precisely so it can cherry-pick upstream fixes. Distributions like Debian make Rust link against the system LLVM but will ensure required bug fixes are present in its system LLVM. What the upstream release branches have isn't generally relevant here for things like this.

joshtriplett · 2021-08-25T21:59:13Z

This will need compiler-team approval for adding m68k-unknown-linux-gnu as a tier 3 target. (Are you volunteering to be the target maintainer of record?) The standard way of doing that is to copy the Tier 3 policy and respond to each bullet point.

This also needs to patch platform-support.md to list the new target.

glaubitz · 2021-08-26T10:53:56Z

This will need compiler-team approval for adding m68k-unknown-linux-gnu as a tier 3 target. (Are you volunteering to be the target maintainer of record?) The standard way of doing that is to copy the Tier 3 policy and respond to each bullet point.

Yes, I'm willing to be the maintainer.

This also needs to patch platform-support.md to list the new target.

OK, I will add that.

jrtc27 · 2021-08-26T11:00:03Z

compiler/rustc_target/src/spec/m68k_unknown_linux_gnu.rs

+    Target {
+        llvm_target: "m68k-unknown-linux-gnu".to_string(),
+        pointer_width: 32,
+        data_layout: "E-m:e-p:32:32-i8:8:8-i16:16:16-i32:16:32-n8:16:32-a:0:16-S16".to_string(),


Suggested change

data_layout: "E-m:e-p:32:32-i8:8:8-i16:16:16-i32:16:32-n8:16:32-a:0:16-S16".to_string(),

data_layout: "E-m:e-p:32:16:32-i8:8:8-i16:16:16-i32:16:32-n8:16:32-a:0:16-S16".to_string(),

I'd have guessed that LLVM would shout at you if it doesn't match what the backend thinks, but perhaps not, maybe that's specific to when Clang and LLVM disagree, given that some of you have clearly already built m68k rust binaries with the older version of this PR that had i32 also incorrectly-aligned.

Have we fixed the data_layout on the LLVM side yet?

jrtc27 · 2021-08-26T11:02:38Z

src/bootstrap/native.rs

@@ -165,7 +165,7 @@ impl Step for Llvm {

        let llvm_exp_targets = match builder.config.llvm_experimental_targets {
            Some(ref s) => s,
-            None => "AVR",
+            None => { "AVR;M68k" }


Not sure why the { } are needed, it's still a single string literal?

glaubitz · 2021-08-26T11:07:36Z

Hmm, odd that it still fails. I thought @ricky26 's patch got backported into the rustc LLVM fork already.

jrtc27 · 2021-08-26T11:22:56Z

You'll need to bump the submodule

wesleywiser

Looks great, thank you!

wesleywiser · 2021-09-17T15:51:43Z

@bors r+

bors · 2021-09-17T15:51:46Z

📌 Commit 5d22b1a has been approved by wesleywiser

Mark-Simulacrum · 2021-09-17T15:55:31Z

Just wanted to drop a thanks for the detailed docs in src/doc/rustc/src/platform-support/m68k-unknown-linux-gnu.md, those look great. ❤️

glaubitz · 2021-09-17T15:57:47Z

Just wanted to drop a thanks for the detailed docs in src/doc/rustc/src/platform-support/m68k-unknown-linux-gnu.md, those look great. heart

Glad they're useful. Appreciate the positive feedback!

bors · 2021-09-20T07:21:13Z

⌛ Testing commit 5d22b1a with merge db1fb85...

bors · 2021-09-20T10:17:01Z

☀️ Test successful - checks-actions
Approved by: wesleywiser
Pushing db1fb85 to master...

rust-timer · 2021-09-20T12:39:37Z

Finished benchmarking commit (db1fb85): comparison url.

Summary: This benchmark run did not return any relevant changes.

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

@rustbot label: -perf-regression

reinvantveer · 2021-09-21T05:15:09Z

Congrats and thanks @glaubitz @ricky26 for making this happen. Retro-enthusiasts around the world rejoice!

plaes · 2021-09-21T12:33:09Z

src/ci/docker/host-x86_64/disabled/dist-m68k-linux/Dockerfile

+  file \
+  curl \
+  ca-certificates \
+  python2.7 \


Is python2.7 really needed?

Probably not. I wrote this Docker file over a year ago when the CI was still using an older version of Ubuntu.

I will verify that the issue and send in a follow-up PR to drop python2.7 if necessary.

Thanks for spotting this.

Pkgsrc changes: * Adapt a couple of patches Upstream changes: Version 1.57.0 (2021-12-02) ========================== Language -------- - [Macro attributes may follow `#[derive]` and will see the original (pre-`cfg`) input.][87220] - [Accept curly-brace macros in expressions, like `m!{ .. }.method()` and `m!{ .. }?`.][88690] - [Allow panicking in constant evaluation.][89508] Compiler -------- - [Create more accurate debuginfo for vtables.][89597] - [Add `armv6k-nintendo-3ds` at Tier 3\*.][88529] - [Add `armv7-unknown-linux-uclibceabihf` at Tier 3\*.][88952] - [Add `m68k-unknown-linux-gnu` at Tier 3\*.][88321] - [Add SOLID targets at Tier 3\*:][86191] `aarch64-kmc-solid_asp3`, `armv7a-kmc-solid_asp3-eabi`, `armv7a-kmc-solid_asp3-eabihf` \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Avoid allocations and copying in `Vec::leak`][89337] - [Add `#[repr(i8)]` to `Ordering`][89507] - [Optimize `File::read_to_end` and `read_to_string`][89582] - [Update to Unicode 14.0][89614] - [Many more functions are marked `#[must_use]`][89692], producing a warning when ignoring their return value. This helps catch mistakes such as expecting a function to mutate a value in place rather than return a new value. Stabilised APIs --------------- - [`[T; N]::as_mut_slice`][`array::as_mut_slice`] - [`[T; N]::as_slice`][`array::as_slice`] - [`collections::TryReserveError`] - [`HashMap::try_reserve`] - [`HashSet::try_reserve`] - [`String::try_reserve`] - [`String::try_reserve_exact`] - [`Vec::try_reserve`] - [`Vec::try_reserve_exact`] - [`VecDeque::try_reserve`] - [`VecDeque::try_reserve_exact`] - [`Iterator::map_while`] - [`iter::MapWhile`] - [`proc_macro::is_available`] - [`Command::get_program`] - [`Command::get_args`] - [`Command::get_envs`] - [`Command::get_current_dir`] - [`CommandArgs`] - [`CommandEnvs`] These APIs are now usable in const contexts: - [`hint::unreachable_unchecked`] Cargo ----- - [Stabilize custom profiles][cargo/9943] Compatibility notes ------------------- Internal changes ---------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. - [Added an experimental backend for codegen with `libgccjit`.][87260] [86191]: rust-lang/rust#86191 [87220]: rust-lang/rust#87220 [87260]: rust-lang/rust#87260 [88243]: rust-lang/rust#88243 [88321]: rust-lang/rust#88321 [88529]: rust-lang/rust#88529 [88690]: rust-lang/rust#88690 [88952]: rust-lang/rust#88952 [89337]: rust-lang/rust#89337 [89507]: rust-lang/rust#89507 [89508]: rust-lang/rust#89508 [89582]: rust-lang/rust#89582 [89597]: rust-lang/rust#89597 [89614]: rust-lang/rust#89614 [89692]: rust-lang/rust#89692 [cargo/9943]: rust-lang/cargo#9943 [`array::as_mut_slice`]: https://doc.rust-lang.org/std/primitive.array.html#method.as_mut_slice [`array::as_slice`]: https://doc.rust-lang.org/std/primitive.array.html#method.as_slice [`collections::TryReserveError`]: https://doc.rust-lang.org/std/collections/struct.TryReserveError.html [`HashMap::try_reserve`]: https://doc.rust-lang.org/std/collections/hash_map/struct.HashMap.html#method.try_reserve [`HashSet::try_reserve`]: https://doc.rust-lang.org/std/collections/hash_set/struct.HashSet.html#method.try_reserve [`String::try_reserve`]: https://doc.rust-lang.org/alloc/string/struct.String.html#method.try_reserve [`String::try_reserve_exact`]: https://doc.rust-lang.org/alloc/string/struct.String.html#method.try_reserve_exact [`Vec::try_reserve`]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.try_reserve [`Vec::try_reserve_exact`]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.try_reserve_exact [`VecDeque::try_reserve`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.try_reserve [`VecDeque::try_reserve_exact`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.try_reserve_exact [`Iterator::map_while`]: https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.map_while [`iter::MapWhile`]: https://doc.rust-lang.org/std/iter/struct.MapWhile.html [`proc_macro::is_available`]: https://doc.rust-lang.org/proc_macro/fn.is_available.html [`Command::get_program`]: https://doc.rust-lang.org/std/process/struct.Command.html#method.get_program [`Command::get_args`]: https://doc.rust-lang.org/std/process/struct.Command.html#method.get_args [`Command::get_envs`]: https://doc.rust-lang.org/std/process/struct.Command.html#method.get_envs [`Command::get_current_dir`]: https://doc.rust-lang.org/std/process/struct.Command.html#method.get_current_dir [`CommandArgs`]: https://doc.rust-lang.org/std/process/struct.CommandArgs.html [`CommandEnvs`]: https://doc.rust-lang.org/std/process/struct.CommandEnvs.html

Pkgsrc changes: * Adjust line numbers in a number of patches * remove the --disable-dist-src option, so that we produce the rust-src rust component, which we upload to LOCALSRC to allow the rust-src package to build, which is needed for rust-analyzer. * Cargo checksum for vendor/cc no longer needs patching; checksum for vendor/libc updated Upstream changes: Version 1.57.0 (2021-12-02) ========================== Language -------- - [Macro attributes may follow `#[derive]` and will see the original (pre-`cfg`) input.][87220] - [Accept curly-brace macros in expressions, like `m!{ .. }.method()` and `m!{ .. }?`.][88690] - [Allow panicking in constant evaluation.][89508] Compiler -------- - [Create more accurate debuginfo for vtables.][89597] - [Add `armv6k-nintendo-3ds` at Tier 3\*.][88529] - [Add `armv7-unknown-linux-uclibceabihf` at Tier 3\*.][88952] - [Add `m68k-unknown-linux-gnu` at Tier 3\*.][88321] - [Add SOLID targets at Tier 3\*:][86191] `aarch64-kmc-solid_asp3`, `armv7a-kmc-solid_asp3-eabi`, `armv7a-kmc-solid_asp3-eabihf` \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Avoid allocations and copying in `Vec::leak`][89337] - [Add `#[repr(i8)]` to `Ordering`][89507] - [Optimize `File::read_to_end` and `read_to_string`][89582] - [Update to Unicode 14.0][89614] - [Many more functions are marked `#[must_use]`][89692], producing a warning when ignoring their return value. This helps catch mistakes such as expecting a function to mutate a value in place rather than return a new value. Stabilised APIs --------------- - [`[T; N]::as_mut_slice`][`array::as_mut_slice`] - [`[T; N]::as_slice`][`array::as_slice`] - [`collections::TryReserveError`] - [`HashMap::try_reserve`] - [`HashSet::try_reserve`] - [`String::try_reserve`] - [`String::try_reserve_exact`] - [`Vec::try_reserve`] - [`Vec::try_reserve_exact`] - [`VecDeque::try_reserve`] - [`VecDeque::try_reserve_exact`] - [`Iterator::map_while`] - [`iter::MapWhile`] - [`proc_macro::is_available`] - [`Command::get_program`] - [`Command::get_args`] - [`Command::get_envs`] - [`Command::get_current_dir`] - [`CommandArgs`] - [`CommandEnvs`] These APIs are now usable in const contexts: - [`hint::unreachable_unchecked`] Cargo ----- - [Stabilize custom profiles][cargo/9943] Compatibility notes ------------------- Internal changes ---------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. - [Added an experimental backend for codegen with `libgccjit`.][87260] [86191]: rust-lang/rust#86191 [87220]: rust-lang/rust#87220 [87260]: rust-lang/rust#87260 [88243]: rust-lang/rust#88243 [88321]: rust-lang/rust#88321 [88529]: rust-lang/rust#88529 [88690]: rust-lang/rust#88690 [88952]: rust-lang/rust#88952 [89337]: rust-lang/rust#89337 [89507]: rust-lang/rust#89507 [89508]: rust-lang/rust#89508 [89582]: rust-lang/rust#89582 [89597]: rust-lang/rust#89597 [89614]: rust-lang/rust#89614 [89692]: rust-lang/rust#89692 [cargo/9943]: rust-lang/cargo#9943 [`array::as_mut_slice`]: https://doc.rust-lang.org/std/primitive.array.html#method.as_mut_slice [`array::as_slice`]: https://doc.rust-lang.org/std/primitive.array.html#method.as_slice [`collections::TryReserveError`]: https://doc.rust-lang.org/std/collections/struct.TryReserveError.html [`HashMap::try_reserve`]: https://doc.rust-lang.org/std/collections/hash_map/struct.HashMap.html#method.try_reserve [`HashSet::try_reserve`]: https://doc.rust-lang.org/std/collections/hash_set/struct.HashSet.html#method.try_reserve [`String::try_reserve`]: https://doc.rust-lang.org/alloc/string/struct.String.html#method.try_reserve [`String::try_reserve_exact`]: https://doc.rust-lang.org/alloc/string/struct.String.html#method.try_reserve_exact [`Vec::try_reserve`]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.try_reserve [`Vec::try_reserve_exact`]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.try_reserve_exact [`VecDeque::try_reserve`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.try_reserve [`VecDeque::try_reserve_exact`]: https://doc.rust-lang.org/std/collections/struct.VecDeque.html#method.try_reserve_exact [`Iterator::map_while`]: https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.map_while [`iter::MapWhile`]: https://doc.rust-lang.org/std/iter/struct.MapWhile.html [`proc_macro::is_available`]: https://doc.rust-lang.org/proc_macro/fn.is_available.html [`Command::get_program`]: https://doc.rust-lang.org/std/process/struct.Command.html#method.get_program [`Command::get_args`]: https://doc.rust-lang.org/std/process/struct.Command.html#method.get_args [`Command::get_envs`]: https://doc.rust-lang.org/std/process/struct.Command.html#method.get_envs [`Command::get_current_dir`]: https://doc.rust-lang.org/std/process/struct.Command.html#method.get_current_dir [`CommandArgs`]: https://doc.rust-lang.org/std/process/struct.CommandArgs.html [`CommandEnvs`]: https://doc.rust-lang.org/std/process/struct.CommandEnvs.html

rust-highfive assigned wesleywiser Aug 25, 2021

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 25, 2021