Support using const pointers in asm `const` operand by nbdd0121 · Pull Request #138618 · rust-lang/rust

nbdd0121 · 2025-03-17T18:07:31Z

Implements RFC#3848 with tracking issue #128464

This adds support of const pointers for asm const in addition to plain integers.

The inline asm! support is implemented using i constraint, and the global_asm! and naked_asm! support is implemented by inserting symbol + offset and make symbol compiler-used. For unnamed consts, it will create additional internal & hidden symbols so that they can be referenced by global_asm.

~~The feature is also implemented for GCC backend but it's untested.~~ Tested now.

fmease · 2025-03-17T18:09:34Z

r? codegen

compiler-errors · 2025-03-18T04:25:43Z

r? compiler-errors

rustbot · 2025-04-10T14:59:14Z

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

Some changes occurred in compiler/rustc_codegen_gcc

cc @antoyo, @GuillaumeGomez

bors · 2025-04-29T06:25:48Z

☔ The latest upstream changes (presumably #140415) made this pull request unmergeable. Please resolve the merge conflicts.

traviscross · 2025-05-04T09:26:42Z

@rustbot author

rustbot · 2025-05-04T09:26:46Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

rustbot · 2025-05-13T10:00:16Z

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

bors · 2025-05-28T05:09:25Z

☔ The latest upstream changes (presumably #141668) made this pull request unmergeable. Please resolve the merge conflicts.

Support using const pointers in asm `const` operand Implements [RFC#3848](rust-lang/rfcs#3848) with tracking issue rust-lang#128464 This adds support of const pointers for asm `const` in addition to plain integers. The inline `asm!` support is implemented using `i` constraint, and the `global_asm!` and `naked_asm!` support is implemented by inserting `symbol + offset` and make `symbol` compiler-used. For unnamed consts, it will create additional internal & hidden symbols so that they can be referenced by global_asm. ~~The feature is also implemented for GCC backend but it's untested.~~ Tested now.

Rollup of 18 pull requests Successful merges: - #138618 (Support using const pointers in asm `const` operand) - #150161 (Remove 'static requirement on try_as_dyn) - #158362 (trait solver: account for universes from replace_bound_vars) - #159173 (Add allowed list check on EII implementations attributes) - #159466 (cmse: clear variant-dependent padding in `enum`s) - #159718 (Make `DocLinkResMap` an `FxIndexMap`) - #155795 (constify `vec![1, 2, 3]` macro) - #157776 (ci: Enable autodiff tests on x86_64 linux) - #157905 (Update comments and add tests for `-Zrandomize-layout` for some guaranteed ZSTs) - #159041 (Reorganize `tests/ui/issues` [22/N]) - #159108 (Reorganize `tests/ui/issues` [23/N]) - #159138 (doc: document wasm import symbol mangling) - #159531 (Reorganize `tests/ui/issues` [28/N]) - #159608 (early_otherwise: Don't hoist dereferences when the otherwise branch is reachable) - #159612 (Reorganize `tests/ui/issues` [29/N]) - #159653 (run `tests/assembly-llvm/asm/aarch64-types.rs` for `aarch64_be`) - #159759 (rustc-dev-guide subtree update) - #159761 (Remove outdated comment for resolve_vars_with_obligations)

Support using const pointers in asm `const` operand Implements [RFC#3848](rust-lang/rfcs#3848) with tracking issue rust-lang#128464 This adds support of const pointers for asm `const` in addition to plain integers. The inline `asm!` support is implemented using `i` constraint, and the `global_asm!` and `naked_asm!` support is implemented by inserting `symbol + offset` and make `symbol` compiler-used. For unnamed consts, it will create additional internal & hidden symbols so that they can be referenced by global_asm. ~~The feature is also implemented for GCC backend but it's untested.~~ Tested now.

folkertdev · 2026-07-23T11:12:25Z

This PR fails the tests/assembly-llvm/asm/global_asm.rs locally on x86_64, and is the likely cause of this rollup failure:

@bors r- #159762 (comment)

cc @jhpratt

This test should maybe be a minicore test anyway?

rust-bors · 2026-07-23T11:12:33Z

This pull request was unapproved.

This PR was contained in a rollup (#159766), which was unapproved.

View changes since this unapproval

The backend now fully supports codegen of const pointers, remove the block inside typeck behind a new feature gate. Tests are also added.

Use edition 2021 so c-string literals are supported.

nbdd0121 · 2026-07-23T17:53:40Z

Sorry, forgot to update the assembly-llvm tests when changing the symbol names. Fixed now.

Changing to use minicore fails with the error below, so I kept it untouched.

error[E0608]: cannot index into a value of type `[{integer}; 2]`
  --> tests/assembly-llvm/asm/global_asm.rs:36:49
   |
36 | global_asm!("lea rax, [rip + {}]", const &[1; 2][1]);
   |                                                 ^^^

error: aborting due to 1 previous error

@rustbot ready

bjorn3 · 2026-07-23T17:55:20Z

r=me once CI passes

folkertdev · 2026-07-23T18:15:35Z

@bors try jobs=x86_64-gnu-llvm-22-*

rust-bors · 2026-07-23T20:11:52Z

☀️ Try build successful (CI)
Build commit: 72cd1f7 (72cd1f73c1af9e44d62bc5d04fc24363d2b3bf3e)
Base parent: 165cce8 (165cce8d820b229af8f6a8226cf0b910b57600ff)

bjorn3 · 2026-07-24T15:30:50Z

@bors r+

rust-bors · 2026-07-24T15:30:54Z

📌 Commit 0316085 has been approved by bjorn3

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 1. This pull request will be tested once the tree is reopened.

Reason for tree closure: spurious CI failures

rust-bors · 2026-07-25T12:36:06Z

💔 Test for 2e47e68 failed: CI

JonathanBrouwer · 2026-07-25T17:35:24Z

@bors retry
Spurious

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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. labels Mar 17, 2025

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nikomatsakis mentioned this pull request Mar 26, 2025

Getting Rust for Linux into stable Rust: language features rust-lang/rust-project-goals#116

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ojeda mentioned this pull request Apr 9, 2025

Rust unstable features needed for the kernel Rust-for-Linux/linux#2

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nbdd0121 force-pushed the asm_const_ptr branch from ffba8e8 to 92c0cc4 Compare April 10, 2025 10:05

nbdd0121 marked this pull request as ready for review April 10, 2025 14:59

tmiasko reviewed Apr 10, 2025

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nbdd0121 force-pushed the asm_const_ptr branch from 92c0cc4 to c7a2301 Compare May 13, 2025 08:27

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nbdd0121 force-pushed the asm_const_ptr branch from c7a2301 to 4240004 Compare May 13, 2025 10:00

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rust-bors Bot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jul 23, 2026

jhpratt mentioned this pull request Jul 23, 2026

Rollup of 18 pull requests #159762

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jhpratt mentioned this pull request Jul 23, 2026

Rollup of 19 pull requests #159766

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nbdd0121 added 3 commits July 23, 2026 18:51

Implement asm_const_ptr feature

73ff59f

The backend now fully supports codegen of const pointers, remove the block inside typeck behind a new feature gate. Tests are also added.

Add test if asm const are MIR inlined and monomorphized twice

5d22dac

Expand invalid-const-operand test case to cover &str and &CStr

0316085

Use edition 2021 so c-string literals are supported.

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Rollup of 18 pull requests #159871

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