SipHasher128 implements short_write in an endian-independent way, yet
its write_xxx Hasher trait methods undo this endian-independence by byte
swapping the integer inputs on big-endian hardware. StableHasher then
adds endian-independence back by also byte-swapping on big-endian
hardware prior to invoking SipHasher128.
This double swap may have the appearance of being a no-op, but is in
fact by design. In particular, we really do want SipHasher128 to be
platform-dependent, in order to be consistent with the libstd SipHasher.
Try to clarify this intent. Also, add and update a couple of unit tests.
Rollup of 7 pull requests
Successful merges:
- #76454 (UI to unit test for those using Cell/RefCell/UnsafeCell)
- #76474 (Add option to pass a custom codegen backend from a driver)
- #76711 (diag: improve closure/generic parameter mismatch)
- #77170 (Remove `#[rustc_allow_const_fn_ptr]` and add `#![feature(const_fn_fn_ptr_basics)]`)
- #77194 (Add doc alias for iterator fold)
- #77288 (fix building libstd for Miri on macOS)
- #77295 (Update unstable-book: Fix ABNF in inline assembly docs)
Failed merges:
r? `@ghost`
Remove `#[rustc_allow_const_fn_ptr]` and add `#![feature(const_fn_fn_ptr_basics)]`
`rustc_allow_const_fn_ptr` was a hack to work around the lack of an escape hatch for the "min `const fn`" checks in const-stable functions. Now that we have co-opted `allow_internal_unstable` for this purpose, we no longer need a bespoke attribute.
Now this functionality is gated under `const_fn_fn_ptr_basics` (how concise!), and `#[allow_internal_unstable(const_fn_fn_ptr_basics)]` replaces `#[rustc_allow_const_fn_ptr]`. `const_fn_fn_ptr_basics` allows function pointer types to appear in the arguments and locals of a `const fn` as well as function pointer casts to be performed inside a `const fn`. Both of these were allowed in constants and statics already. Notably, this does **not** allow users to invoke function pointers in a const context. Presumably, we will use a nicer name for that (`const_fn_ptr`?).
r? @oli-obk
diag: improve closure/generic parameter mismatch
Fixes#51154.
This PR improves the diagnostic when a type parameter is expected and a closure is found, noting that each closure has a distinct type and therefore could not always match the caller-chosen type of the parameter.
r? @estebank
Add option to pass a custom codegen backend from a driver
This allows the driver to pass information to the codegen backend. For example the headcrab debugger may in the future want to use cg_clif to JIT code to be injected in the debuggee. This would PR make it possible to tell cg_clif which symbol can be found at which address and to tell it to inject the JITed code into the right process.
This PR may also help with https://github.com/rust-lang/miri/pull/1540 by allowing miri to provide a codegen backend that only emits metadata and doesn't perform any codegen.
cc @nbaksalyar (headcrab)
cc @RalfJung (miri)
[mir-opt] Introduce a new flag to enable experimental/unsound mir opts
This implements part of https://github.com/rust-lang/compiler-team/issues/319. The exact name of this flag was not decided as part of that MCP and some people expressed that it should include "unsound" in some way.
I've chosen to use `enable-experimental-unsound-mir-opts` as the name. While long, I don't think that matters too much as really it will only be used by some mir-opt tests. If you object or have a better name, please leave a comment!
r? `@oli-obk`
cc `@rust-lang/wg-mir-opt` `@RalfJung`
Deduplicate and generalize some (de/)serializer impls
I noticed this while implementing #77227 and getting a "not implemented for [T; 16]" error. There's likely more things we can deduplicate in this file, but I didn't need any additional changes.
Replace `discriminant_switch_effect` with more general version
#68528 added a new edge-specific effect for `SwitchInt` terminators, `discriminant_switch_effect`, to the dataflow framework. While this accomplished the short-term goal of making drop elaboration more precise, it wasn't really useful in other contexts: It only supported `SwitchInt`s on the discriminant of an `enum` and did not allow effects to be applied along the "otherwise" branch. In const-propagation, for example, arbitrary edge-specific effects for the targets of a `SwitchInt` can be used to remember the value a `match` scrutinee must have in each arm.
This PR replaces `discriminant_switch_effect` with a more general `switch_int_edge_effects` method. The new method has a slightly different interface from the other edge-specific effect methods (e.g. `call_return_effect`). This divergence is explained in the new method's documentation, and reading the changes to the various dataflow impls as well as `direction.rs` should further clarify things. This PR should not change behavior.
Small improvements in liveness pass
* Remove redundant debug logging (`add_variable` already contains logging).
* Remove redundant fields for a number of live nodes and variables.
* Delay conversion from a symbol to a string until linting.
* Inline contents of specials struct.
* Remove unnecessary local variable exit_ln.
* Use newtype_index for Variable and LiveNode.
* Access live nodes directly through self.lnks[ln].
No functional changes intended (except those related to the logging).
This was a hack to work around the lack of an escape hatch for the "min
`const fn`" checks in const-stable functions. Now that we have co-opted
`allow_internal_unstable` for this purpose, we no longer need the
bespoke attribute.
Separate `private_intra_doc_links` and `broken_intra_doc_links` into separate lints
This is not ideal because it means `deny(broken_intra_doc_links)` will
no longer `deny(private_intra_doc_links)`. However, it can't be fixed
with a new lint group, because `broken` is already in the `rustdoc` lint
group; there would need to be a way to nest groups somehow.
This also removes the early `return` so that the link will be generated
even though it gives a warning.
r? @Manishearth
cc @ecstatic-morse (https://github.com/rust-lang/rust/pull/77242#issuecomment-699565095)
Check for missing const-stability attributes in `rustc_passes`
Currently, this happens as a side effect of `is_min_const_fn`, which is non-obvious. Also adds a test for this case, since we didn't seem to have one before.
This is not ideal because it means `deny(broken_intra_doc_links)` will
no longer `deny(private_intra_doc_links)`. However, it can't be fixed
with a new lint group, because `broken` is already in the `rustdoc` lint
group; there would need to be a way to nest groups somehow.
This also removes the early `return` so that the link will be generated
even though it gives a warning.
might_permit_raw_init: also check aggregate fields
This is the next step for https://github.com/rust-lang/rust/issues/66151: when doing `mem::zeroed`/`mem::uninitialized`, also recursively check fields of aggregates (except for arrays) for whether they permit zero/uninit initialization.
Refactor and fix intra-doc link diagnostics, and fix links to primitives
Closes https://github.com/rust-lang/rust/issues/76925, closes https://github.com/rust-lang/rust/issues/76693, closes https://github.com/rust-lang/rust/issues/76692.
Originally I only meant to fix#76925. But the hack with `has_primitive` was so bad it was easier to fix the primitive issues than to try and work around it.
Note that this still has one bug: `std::primitive::i32::MAX` does not resolve. However, this fixes the ICE so I'm fine with fixing the link in a later PR.
This is part of a series of refactors to make #76467 possible.
This is best reviewed commit-by-commit; it has detailed commit messages.
r? `@euclio`
This patch also:
* Add soft-float supports: only f32
* zero-extend i8/i16 to i32 because MIPS only supports register-length
arithmetic.
* Update table in asm! chapter in unstable book.
Return values up to 128 bits in registers
This fixes https://github.com/rust-lang/rust/issues/26494#issuecomment-619506345 by making Rust's default ABI pass return values up to 128 bits in size in registers, just like the System V ABI.
The result is that these methods from the comment linked above now generate the same code, making the Rust ABI as efficient as the `"C"` ABI:
```rust
pub struct Stats { x: u32, y: u32, z: u32, }
pub extern "C" fn sum_c(a: &Stats, b: &Stats) -> Stats {
return Stats {x: a.x + b.x, y: a.y + b.y, z: a.z + b.z };
}
pub fn sum_rust(a: &Stats, b: &Stats) -> Stats {
return Stats {x: a.x + b.x, y: a.y + b.y, z: a.z + b.z };
}
```
```asm
sum_rust:
movl (%rsi), %eax
addl (%rdi), %eax
movl 4(%rsi), %ecx
addl 4(%rdi), %ecx
movl 8(%rsi), %edx
addl 8(%rdi), %edx
shlq $32, %rcx
orq %rcx, %rax
retq
```
pretty-print-reparse hack: Rename some variables for clarity
This will also make it easier to make the comparisons asymmetric.
Also one impossible case is removed.
r? @Aaron1011
Move helper function for `missing_const_for_fn` out of rustc to clippy
cc @rust-lang/clippy @ecstatic-morse #76618
r? @Manishearth
I also removed all support for suggesting a function could be `const fn` when that would require feature gates to actually work.
This means we'll now have to maintain this ourselves in clippy, but that's how most lints work anyway, so...
Late link args order
MSYS2 changed how winpthreads is built and as the result it now depends on more mingw-w64 libraries.
This PR affects only MinGW targets since nobody else is using `late_link_args_{dynamic,static}`. Now the order is similar to how it used to be before https://github.com/rust-lang/rust/pull/67502.
Enable const propagation into operands at mir_opt_level=2
Feature was added in #74507 but gated with `mir_opt_level>=3` because of compile time regressions. Let's see whether the LLVM 11 update solves that.
As the [perf results](https://github.com/rust-lang/rust/pull/77107#issuecomment-697668154) show, enabling this optimization results in a lot less regression as before.
cc @oli-obk
r? @ghost
Encode less metadata for proc-macro crates
Currently, we serialize the same crate metadata for proc-macro crates as
we do for normal crates. This is quite wasteful - almost none of this
metadata is ever used, and much of it can't even be deserialized (if it
contains a foreign `CrateNum`).
This PR changes metadata encoding to skip encoding the majority of crate
metadata for proc-macro crates. Most of the `Lazy<[T]>` fields are left
completetly empty, while the non-lazy fields are left as-is.
Additionally, proc-macros now have a def span that does not include
their body. This was done for normal functions in #75465, but was missed
for proc-macros.
As a result of this PR, we should only ever encode local `CrateNum`s
when encoding proc-macro crates. I've added a specialized serialization
impl for `CrateNum` to assert this.
Currently, we serialize the same crate metadata for proc-macro crates as
we do for normal crates. This is quite wasteful - almost none of this
metadata is ever used, and much of it can't even be deserialized (if it
contains a foreign `CrateNum`).
This PR changes metadata encoding to skip encoding the majority of crate
metadata for proc-macro crates. Most of the `Lazy<[T]>` fields are left
completetly empty, while the non-lazy fields are left as-is.
Additionally, proc-macros now have a def span that does not include
their body. This was done for normal functions in #75465, but was missed
for proc-macros.
As a result of this PR, we should only ever encode local `CrateNum`s
when encoding proc-macro crates. I've added a specialized serialization
impl for `CrateNum` to assert this.
