Sized Hierarchy: Part I
This patch implements the non-const parts of rust-lang/rfcs#3729. It introduces two new traits to the standard library, `MetaSized` and `PointeeSized`. See the RFC for the rationale behind these traits and to discuss whether this change makes sense in the abstract.
These traits are unstable (as is their constness), so users cannot refer to them without opting-in to `feature(sized_hierarchy)`. These traits are not behind `cfg`s as this would make implementation unfeasible, there would simply be too many `cfg`s required to add the necessary bounds everywhere. So, like `Sized`, these traits are automatically implemented by the compiler.
RFC 3729 describes changes which are necessary to preserve backwards compatibility given the introduction of these traits, which are implemented and as follows:
- `?Sized` is rewritten as `MetaSized`
- `MetaSized` is added as a default supertrait for all traits w/out an explicit sizedness supertrait already.
There are no edition migrations implemented in this, as these are primarily required for the constness parts of the RFC and prior to stabilisation of this (and so will come in follow-up PRs alongside the const parts). All diagnostic output should remain the same (showing `?Sized` even if the compiler sees `MetaSized`) unless the `sized_hierarchy` feature is enabled.
Due to the use of unstable extern types in the standard library and rustc, some bounds in both projects have had to be relaxed already - this is unfortunate but unavoidable so that these extern types can continue to be used where they were before. Performing these relaxations in the standard library and rustc are desirable longer-term anyway, but some bounds are not as relaxed as they ideally would be due to the inability to relax `Deref::Target` (this will be investigated separately).
It is hoped that this is implemented such that it could be merged and these traits could exist "under the hood" without that being observable to the user (other than in any performance impact this has on the compiler, etc). Some details might leak through due to the standard library relaxations, but this has not been observed in test output.
**Notes:**
- Any commits starting with "upstream:" can be ignored, as these correspond to other upstream PRs that this is based on which have yet to be merged.
- This best reviewed commit-by-commit. I've attempted to make the implementation easy to follow and keep similar changes and test output updates together.
- Each commit has a short description describing its purpose.
- This patch is large but it's primarily in the test suite.
- I've worked on the performance of this patch and a few optimisations are implemented so that the performance impact is neutral-to-minor.
- `PointeeSized` is a different name from the RFC just to make it more obvious that it is different from `std::ptr::Pointee` but all the names are yet to be bikeshed anyway.
- `@nikomatsakis` has confirmed [that this can proceed as an experiment from the t-lang side](https://rust-lang.zulipchat.com/#narrow/channel/435869-project-goals/topic/SVE.20and.20SME.20on.20AArch64.20.28goals.23270.29/near/506196491)
- FCP in https://github.com/rust-lang/rust/pull/137944#issuecomment-2912207485Fixesrust-lang/rust#79409.
r? `@ghost` (I'll discuss this with relevant teams to find a reviewer)
Move metadata object generation for dylibs to the linker code
This deduplicates some code between codegen backends and may in the future allow adding extra metadata that is only known at link time.
Prerequisite of https://github.com/rust-lang/rust/issues/96708.
Simplify implementation of Rust intrinsics by using type parameters in the cache
The current implementation of intrinsics have a lot of duplication to handle different overloads of overloaded LLVM intrinsic. This PR uses the **base name and the type parameters** in the cache instead of the full, overloaded name. This has the benefit that `call_intrinsic` doesn't need to provide the full name, rather the type parameters (which is most of the time more available). This uses `LLVMIntrinsicCopyOverloadedName2` to get the overloaded name from the base name and the type parameters, and only uses it to declare the function.
(originally was part of rust-lang/rust#140763, split off later)
`@rustbot` label A-codegen A-LLVM
r? codegen
Unimplement unsized_locals
Implements https://github.com/rust-lang/compiler-team/issues/630
Tracking issue here: https://github.com/rust-lang/rust/issues/111942
Note that this just removes the feature, not the implementation, and does not touch `unsized_fn_params`. This is because it is required to support `Box<dyn FnOnce()>: FnOnce()`.
There may be more that should be removed (possibly in follow up prs)
- the `forget_unsized` function and `forget` intrinsic.
- the `unsized_locals` test directory; I've just fixed up the tests for now
- various codegen support for unsized values and allocas
cc ``@JakobDegen`` ``@oli-obk`` ``@Noratrieb`` ``@programmerjake`` ``@bjorn3``
``@rustbot`` label F-unsized_locals
Fixesrust-lang/rust#79409
add `extern "custom"` functions
tracking issue: rust-lang/rust#140829
previous discussion: https://github.com/rust-lang/rust/issues/140566
In short, an `extern "custom"` function is a function with a custom ABI, that rust does not know about. Therefore, such functions can only be defined with `#[unsafe(naked)]` and `naked_asm!`, or via an `extern "C" { /* ... */ }` block. These functions cannot be called using normal rust syntax: calling them can only be done from inline assembly.
The motivation is low-level scenarios where a custom calling convention is used. Currently, we often pick `extern "C"`, but that is a lie because the function does not actually respect the C calling convention.
At the moment `"custom"` seems to be the name with the most support. That name is not final, but we need to pick something to actually implement this.
r? `@traviscross`
cc `@tgross35`
try-job: x86_64-apple-2
retpoline and retpoline-external-thunk flags (target modifiers) to enable retpoline-related target features
`-Zretpoline` and `-Zretpoline-external-thunk` flags are target modifiers (tracked to be equal in linked crates).
* Enables target features for `-Zretpoline-external-thunk`:
`+retpoline-external-thunk`, `+retpoline-indirect-branches`, `+retpoline-indirect-calls`.
* Enables target features for `-Zretpoline`:
`+retpoline-indirect-branches`, `+retpoline-indirect-calls`.
It corresponds to clang -mretpoline & -mretpoline-external-thunk flags.
Also this PR forbids to specify those target features manually (warning).
Issue: rust-lang/rust#116852
store `target.min_global_align` as an `Align`
Parse the alignment properly when the target is defined/parsed, and error out on invalid alignment values. That means this work doesn't need to happen for every global in each backend.
Many of `std`'s dependency have a dependency on the crates.io
`compiler-builtins` when used with the feature
`rustc-std-workspace-core`. Use a Cargo patch to select the in-tree
version instead.
`compiler-builtins` is also added as a dependency of
`rustc-std-workspace-core` so these crates can remove their crates.io
dependency in the future.
Replace ad-hoc ABI "adjustments" with an `AbiMap` to `CanonAbi`
Our `conv_from_spec_abi`, `adjust_abi`, and `is_abi_supported` combine to give us a very confusing way of reasoning about what _actual_ calling convention we want to lower our code to and whether we want to compile the resulting code at all. Instead of leaving this code as a miniature adventure game in which someone tries to combine stateful mutations into a Rube Goldberg machine that will let them escape the maze and arrive at the promised land of codegen, we let `AbiMap` devour this complexity. Once you have an `AbiMap`, you can answer which `ExternAbi`s will lower to what `CanonAbi`s (and whether they will lower at all).
Removed:
- `conv_from_spec_abi` replaced by `AbiMap::canonize_abi`
- `adjust_abi` replaced by same
- `Conv::PreserveAll` as unused
- `Conv::Cold` as unused
- `enum Conv` replaced by `enum CanonAbi`
target-spec.json changes:
- If you have a target-spec.json then now your "entry-abi" key will be specified in terms of one of the `"{abi}"` strings Rust recognizes, e.g.
```json
"entry-abi": "C",
"entry-abi": "win64",
"entry-abi": "aapcs",
```
atomic_load intrinsic: use const generic parameter for ordering
We have a gazillion intrinsics for the atomics because we encode the ordering into the intrinsic name rather than making it a parameter. This is particularly bad for those operations that take two orderings. Let's fix that!
This PR only converts `load`, to see if there's any feedback that would fundamentally change the strategy we pursue for the const generic intrinsics.
The first two commits are preparation and could be a separate PR if you prefer.
`@BoxyUwU` -- I hope this is a use of const generics that is unlikely to explode? All we need is a const generic of enum type. We could funnel it through an integer if we had to but an enum is obviously nicer...
`@bjorn3` it seems like the cranelift backend entirely ignores the ordering?
There is no safety contract and I don't think any of them can actually
cause UB in more ways than passing malicious source code to rustc can.
While LtoModuleCodegen::optimize says that the returned ModuleCodegen
points into the LTO module, the LTO module has already been dropped by
the time this function returns, so if the returned ModuleCodegen indeed
points into the LTO module, we would have seen crashes on every LTO
compilation, which we don't. As such the comment is outdated.
- Rename `USED` to `USED_COMPILER` to better reflect its behavior.
- Reorder some items to group the used and allocator flags together
- Renumber them without gaps
make `rustc_attr_parsing` less dominant in the rustc crate graph
It has/had a glob re-export of `rustc_attr_data_structures`, which is a crate much lower in the graph, and a lot of crates were using it *just* (or *mostly*) for that re-export, while they can rely on `rustc_attr_data_structures` directly.
Previous graph:
Graph with this PR:
The first commit keeps the re-export, and just changes the dependency if possible. The second commit is the "breaking change" which removes the re-export, and "explicitly" adds the `rustc_attr_data_structures` dependency where needed. It also switches over some src/tools/*.
The second commit is actually a lot more involved than I expected. Please let me know if it's a better idea to back it out and just keep the first commit.
Use intrinsics for `{f16,f32,f64,f128}::{minimum,maximum}` operations
This PR creates intrinsics for `{f16,f32,f64,f64}::{minimum,maximum}` operations.
This wasn't done when those operations were added as the LLVM support was too weak but now that LLVM has libcalls for unsupported platforms we can finally use them.
Cranelift and GCC[^1] support are partial, Cranelift doesn't support `f16` and `f128`, while GCC doesn't support `f16`.
r? `@tgross35`
try-job: aarch64-gnu
try-job: dist-various-1
try-job: dist-various-2
[^1]: https://www.gnu.org/software///gnulib/manual/html_node/Functions-in-_003cmath_002eh_003e.html
remove 'unordered' atomic intrinsics
As their doc comment already indicates, these operations do not currently have a place in our memory model. The intrinsics were introduced to support a hack in compiler-builtins, but that hack recently got removed (see https://github.com/rust-lang/compiler-builtins/issues/788).
