add `naked_asm!` macro for use in `#[naked]` functions #128651

folkertdev · 2024-08-04T16:08:09Z

tracking issue: #90957

Adds the core::arch::naked_asm macro, to be used in #[naked] functions, but providing better error messages and a place to explain the restrictions on assembly in naked functions.

This PR does not yet require that the naked_asm! macro is used inside of #[naked] functions:

the asm! macro can still be used in #[naked] functions currently, with the same restrictions and error messages as before.
the naked_asm! macro can be used outside of #[naked] functions. It has not yet been decided whether that should be allowed long-term.

In this PR, the parsing code of naked_asm! now enforces the restrictions on assembly in naked functions, with the exception of checking that the noreturn option is specified. It also has not currently been decided if noreturn should be implicit or not.

This PR looks large because it touches a bunch of tests. The code changes are mostly straightforward I think: we now have 3 flavors of assembly macro, and that information must be propagated through the parsing code and error messages.

cc @Lokathor

r? @Amanieu

Lokathor · 2024-08-04T16:18:29Z

My own vote is that the noreturn option should not be placed by users into the naked_asm macro. The same option should not mean one thing for asm and then nearly the opposite in naked_asm. That's needlessly confusing.

There are two reasonable designs that spring to mind:

naked_asm uses an alternative token such as nakedreturn, which still lets the reader know that there's some funny control flow going on, but which can be documented separately and compiler checked separately.
naked_asm simply doesn't have users write any return related option word at all.

rustbot · 2024-08-04T16:27:10Z

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

folkertdev · 2024-08-04T16:33:18Z

I agree, and think we can get away with making the noreturn implicit. Naked functions are an advanced feature anyway, so if you're writing naked_asm! it's up to you to make sure the safety conditions are satisfied.

But also, I don't want to touch the validation logic in this PR, it can be handled when we disallow the use of asm! in naked functions.

Amanieu

LGTM, but I would make one change and remove the noreturn attribute from naked_asm, changing it to always return !.

The reason for this is that we want existing users of naked function to transition to using naked_asm instead and we want to eliminate noreturn as part of this transition.

r=me

folkertdev · 2024-09-05T11:27:51Z

cool, we discussed noreturn a bit in the comments here earlier, and it looks like everyone is in agreement that the noreturn should be dropped.

I did not implement that here yet because then naked_asm! will fail the validation pass that is currently applied to asm! which mandates that the noreturn is present. So to make naked_asm! work without noreturn, that validation pass needs to be removed and in practice that means that asm! should also be disallowed in naked functions. That was always the plan of course, I just tried to break it up into smaller parts.

But, I'll line up those changes and then we can see how to merge them: either in 2 parts or as one combined unit.

Amanieu · 2024-09-05T11:47:56Z

It's probably fine to go ahead and disallow asm in naked functions as part of this PR. It will be easier this way.

compiler/rustc_ast/src/ast.rs

compiler/rustc_hir_typeck/src/expr.rs

compiler/rustc_passes/src/errors.rs

compiler/rustc_passes/src/naked_functions.rs

rustbot · 2024-09-05T16:12:08Z

This PR modifies tests/run-make/. If this PR is trying to port a Makefile
run-make test to use rmake.rs, please update the
run-make port tracking issue
so we can track our progress. You can either modify the tracking issue
directly, or you can comment on the tracking issue and link this PR.

cc @jieyouxu

rustbot · 2024-09-05T18:35:27Z

This PR changes MIR

cc @oli-obk, @RalfJung, @JakobDegen, @davidtwco, @celinval, @vakaras

Some changes occurred to the CTFE / Miri engine

cc @rust-lang/miri

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

folkertdev · 2024-09-05T18:39:38Z

well that pinged a bunch of people.

The thing I had to solve was that the InlineAsmOptions::NORETURN value is (ab)used to answer the question "will this asm block diverge?", which is used in various places in type checking and codegen. The naked_asm! macro does not set this option, but does diverge. In hindsight that option maybe should have been named diverges? anyway, the current solution is a bit noisy, so if anyone has better ideas let me know.

…tgross35 update `compiler-builtins` to 0.1.126 this requires the addition of a bootstrap variant of the new `naked_asm!` macro r? ``@tgross35`` extracted from rust-lang#128651

…tgross35 update `compiler-builtins` to 0.1.126 this requires the addition of a bootstrap variant of the new `naked_asm!` macro r? `@tgross35` extracted from rust-lang#128651

Rollup merge of rust-lang#130875 - folkertdev:naked-asm-bootstrap, r=tgross35 update `compiler-builtins` to 0.1.126 this requires the addition of a bootstrap variant of the new `naked_asm!` macro r? `@tgross35` extracted from rust-lang#128651

Amanieu

LGTM with one minor nit.

r=me

Amanieu · 2024-10-05T16:47:18Z

compiler/rustc_passes/src/naked_functions.rs

+                        self.items.push((ItemKind::NakedAsm, span));
+                    }
+                    rustc_ast::AsmMacro::GlobalAsm => {
+                        // not allowed in this position


Make this a span_bug!.

Amanieu · 2024-10-05T16:56:28Z

@bors delegate+

bors · 2024-10-05T16:56:31Z

✌️ @folkertdev, you can now approve this pull request!

If @Amanieu told you to "r=me" after making some further change, please make that change, then do @bors r=@Amanieu

also disallow the `noreturn` option, and infer `naked_asm!` as `!`

…_asm!`

- fix for divergence - fix error message - fix another cranelift test - fix some cranelift things - don't set the NORETURN option for naked asm - fix use of naked_asm! in doc comment - fix use of naked_asm! in run-make test - use `span_bug` in unreachable branch

folkertdev · 2024-10-06T20:04:38Z

@bors r=@Amanieu

bors · 2024-10-06T20:04:40Z

📌 Commit 5fc60d1 has been approved by Amanieu

It is now in the queue for this repository.

bors · 2024-10-06T21:51:22Z

⌛ Testing commit 5fc60d1 with merge 1b3b8e7...

bors · 2024-10-07T00:44:33Z

☀️ Test successful - checks-actions
Approved by: Amanieu
Pushing 1b3b8e7 to master...

rust-timer · 2024-10-07T02:01:36Z

Finished benchmarking commit (1b3b8e7): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

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

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Results (secondary 0.6%)

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	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.6%	[0.6%, 0.6%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 7.9%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	7.9%	[2.5%, 10.0%]	7
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

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Bootstrap: 774.699s -> 774.632s (-0.01%)
Artifact size: 329.53 MiB -> 329.53 MiB (-0.00%)

…10-07 This feature has been added recently in this pull request: rust-lang/rust#128651 After this pull, `core::arch::asm!` can no longer be used in #[naked] functions. We should use `core::arch::naked_asm!` instead. Tested rustc version: ``` rustc -vV rustc 1.83.0-nightly (3ae715c8c 2024-10-07) binary: rustc commit-hash: 3ae715c8c63f9aeac47cbf7d8d9dadb3fa32c638 commit-date: 2024-10-07 host: x86_64-pc-windows-msvc release: 1.83.0-nightly LLVM version: 19.1.1 ``` Signed-off-by: Zhouqi Jiang <luojia@hust.edu.cn>

…r rustc nightly 2024-10-07 Ref: rust-lang/rust#128651 Signed-off-by: Zhouqi Jiang <luojia@hust.edu.cn>

rustbot assigned Amanieu Aug 4, 2024

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 Aug 4, 2024

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folkertdev force-pushed the naked-asm-macro-v2 branch from 7dbd972 to bfa880f Compare August 4, 2024 16:27

antoyo mentioned this pull request Aug 17, 2024

arbitrary_self_types_pointers_and_wrappers fails on aarch64 due to stack corruption with libgcc atomics rust-lang/rustc_codegen_gcc#544

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folkertdev force-pushed the naked-asm-macro-v2 branch from bfa880f to f25a97c Compare August 22, 2024 09:29

folkertdev mentioned this pull request Sep 3, 2024

Tracking Issue for RFC #2972: Constrained Naked Functions #90957

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folkertdev force-pushed the naked-asm-macro-v2 branch from c1e29cb to 06dfdbe Compare September 5, 2024 16:12

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folkertdev force-pushed the naked-asm-macro-v2 branch from d2aa0e0 to 56b14b1 Compare September 5, 2024 19:22

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Amanieu approved these changes Oct 5, 2024

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folkertdev added 8 commits October 6, 2024 18:12

implement naked_asm macro

aa5bbf0

use naked_asm! in tests/ui/asm/naked-functions.rs

0aec555

use naked_asm! in naked-function tests

47b42be

use naked_asm! in feature-gate-naked_functions test

1a9c1cb

disallow asm! in #[naked] functions

562ec5a

also disallow the `noreturn` option, and infer `naked_asm!` as `!`

more asm! -> naked_asm! in tests

bc0a954

remove checks that are now performed during macro expansion of `naked…

10fa482

…_asm!`

folkertdev force-pushed the naked-asm-macro-v2 branch from 8a188bd to 5fc60d1 Compare October 6, 2024 17:00

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 Oct 6, 2024

bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 7, 2024

bors merged commit 1b3b8e7 into rust-lang:master Oct 7, 2024
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rustbot added this to the 1.83.0 milestone Oct 7, 2024

bors mentioned this pull request Oct 7, 2024

codegen #[naked] functions using global asm #128004

Open

luojia65 added a commit to rustsbi/bouffalo-hal that referenced this pull request Oct 10, 2024

rt: use core::arch::naked_asm in naked functions to ensure build unde…

bfda4cb

…r rustc nightly 2024-10-07 Ref: rust-lang/rust#128651 Signed-off-by: Zhouqi Jiang <luojia@hust.edu.cn>

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add `naked_asm!` macro for use in `#[naked]` functions #128651

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add naked_asm! macro for use in #[naked] functions #128651

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add `naked_asm!` macro for use in `#[naked]` functions #128651

add `naked_asm!` macro for use in `#[naked]` functions #128651