Stable hashing: add comments and tests concerning platform-independence
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.
---
Previous commit text:
~SipHasher128: fix platform-independence confusion~
~StableHasher is supposed to ensure platform independence by converting
integers to little-endian and extending isize and usize to 64 bits as
necessary, but in fact, much of that work is already handled by
SipHasher128.~
~In particular, SipHasher128 implements short_write in an
endian-independent way, yet both StableHasher and SipHasher128
additionally attempt to achieve endian-independence by byte swapping on
BE hardware before invoking short writes. This double swap has no
effect, so let's remove it.~
~Because short_write is endian-independent, SipHasher128 is already
handling part of the platform-independence, and it would be somewhat
difficult to make it *not* handle that part with the current
implementation. As splitting platform-independence responsibilities
between StableHasher and SipHasher128 would be confusing, let's make
SipHasher128 handle all of it.~
~Finally, update some incorrect comments and increase test coverage.
Unit tests pass on both LE and BE systems.~
const evaluatable: improve `TooGeneric` handling
Instead of emitting an error in `fulfill`, we now correctly stall on inference variables.
As `const_eval_resolve` returns `ErrorHandled::TooGeneric` when encountering generic parameters on which
we actually do want to error, we check for inference variables and eagerly emit an error if they don't exist, returning `ErrorHandled::Reported` instead.
Also contains a small bugfix for `ConstEquate` where we previously only stalled on type variables. This is probably a leftover from
when we did not yet support stalling on const inference variables.
r? @oli-obk cc @varkor @eddyb
Defer Apple SDKROOT detection to link time.
This defers the detection of the SDKROOT for Apple iOS/tvOS targets to link time, instead of when the `Target` is defined. This allows commands that don't need to link to work (like `rustdoc` or `rustc --print=target-list`). This also makes `--print=target-list` a bit faster.
This also removes the note in the platform support documentation about these targets being missing. When I wrote it, I misunderstood how the SDKROOT stuff worked.
Notes:
* This means that JSON spec targets can't explicitly override these flags. I think that is probably fine, as I believe the value is generally required, and can be set with the SDKROOT environment variable.
* This changes `x86_64-apple-tvos` to use `appletvsimulator`. I think the original code was wrong (it was using `iphonesimulator`). Also, `x86_64-apple-tvos` seems broken in general, and I cannot build it locally. The `data_layout` does not appear to be correct (it is a copy of the arm64 layout instead of the x86_64 layout). I have not tried building Apple's LLVM to see if that helps, but I suspect it is just wrong (I'm uncertain since I don't know how the tvOS simulator works with its bitcode-only requirements).
* I'm tempted to remove the use of `Result` for built-in target definitions, since I don't think they should be fallible. This was added in https://github.com/rust-lang/rust/pull/34980, but that only relates to JSON definitions. I think the built-in targets shouldn't fail. I can do this now, or not.
Fixes#36156Fixes#76584
Fix recursive nonterminal expansion during pretty-print/reparse check
Makes progress towards #43081
In PR #73084, we started recursively expanded nonterminals during the
pretty-print/reparse check, allowing them to be properly compared
against the reparsed tokenstream.
Unfortunately, the recursive logic in that PR only handles the case
where a nonterminal appears inside a `TokenTree::Delimited`. If a
nonterminal appears directly in the expanded tokens of another
nonterminal, the inner nonterminal will not be expanded.
This PR fixes the recursive expansion of nonterminals, ensuring that
they are expanded wherever they occur.
Rollup of 12 pull requests
Successful merges:
- #77037 (more tiny clippy cleanups)
- #77233 (BTreeMap: keep an eye out on the size of the main components)
- #77280 (Ensure that all LLVM components requested by tests are available on CI)
- #77284 (library: Forward compiler-builtins "mem" feature)
- #77296 (liveness: Use Option::None to represent absent live nodes)
- #77322 (Add unstable book docs for `-Zunsound-mir-opts`)
- #77328 (Use `rtassert!` instead of `assert!` from the child process after fork() in std::sys::unix::process::Command::spawn())
- #77331 (Add test for async/await combined with const-generics.)
- #77338 (Fix typo in alloc vec comment)
- #77340 (Alloc vec use imported path)
- #77345 (Add test for issue #74761)
- #77348 (Update books)
Failed merges:
r? `@ghost`
Add support for cmse_nonsecure_entry attribute
This pull request adds the `cmse_nonsecure_entry` attribute under an unstable feature.
I was not sure if it was fine for me to send directly the pull-request or if I should submit a RFC first. I was told on Zulip that it was fine to do so but please close it if I need first submit a RFC or follow another process instead.
The `cmse_nonsecure_entry` attribute is a LLVM attribute that will be available in LLVM 11. I plan to rebase on the [upgrade PR](https://github.com/rust-lang/rust/pull/73526) once merged to make this one compile.
This attribute modifies code generation of the function as explained [here](https://developer.arm.com/documentation/ecm0359818/latest/) to make it work with the TrustZone-M hardware feature. This feature is only available on `thumbv8m` targets so I created an error for that if one tries to use this attribute for another target.
I added this attribute in Rust as any other LLVM attribute are added but since this one is target-dependent I am not sure if it was the best thing to do. Please indicate me if you think of other ways, like isolating target-dependent attributes together.
----------------
Tracking issue: https://github.com/rust-lang/rust/issues/75835
This patch adds support for the LLVM cmse_nonsecure_entry attribute.
This is a target-dependent attribute that only has sense for the
thumbv8m Rust targets.
You can find more information about this attribute here:
https://developer.arm.com/documentation/ecm0359818/latest/
Signed-off-by: Hugues de Valon <hugues.devalon@arm.com>
Secure entry functions do not support if arguments are passed on the
stack. An "unsupported" diagnostic will be emitted by LLVM if that is
the case.
This commits adds support in Rust for that diagnostic so that an error
will be output if that is the case!
Signed-off-by: Hugues de Valon <hugues.devalon@arm.com>
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.
This helper function was meant to reduce code duplication between
const-checking pre- and post-drop-elaboration. Most of the functionality
is only relevant for the pre-drop-elaboration pass.
Liveness refactoring continued
* Move body_owner field from IrMaps to Liveness (the only user of the field).
* Use upvars instead of FnKind to check for closures (avoids FnKind, will be useful when checking all bodies, not just fns).
* Use visit_param to add variables corresponding to params.
* Store upvars_mentioned inside Liveness struct.
* Inline visitor implementation for IrMaps, avoiding unnecessary indirection.
* Test interaction with automatically_derived attribute (not covered by any of existing tests).
No functional changes intended.
expand: Stop normalizing `NtIdent`s before passing them to built-in macros
Built-in macros should be able to deal with `NtIdents` in the input by themselves like any other parser code.
You can't imagine how bad mutable AST visitors are, *especially* if they are modifying tokens.
This is one step towards removing token visiting from the visitor infrastructure (https://github.com/rust-lang/rust/pull/77271 also works in this direction.)
Optimize `IntRange::from_pat`, then shrink `ParamEnv`
Resolves#77058.
r? `@Mark-Simulacrum`
cc `@vandenheuvel`
Looking at the output of `perf report` for #76244, the hot instructions seemed to be around the call to `pat_constructor` in `IntRange::from_pat`. I carried out an obvious optimization, but it actually made the instruction count higher (see #77075). However, it seems to have mitigated whatever was causing the pipeline stalls, so when combined with #76244, it's a net win.
As you can see below, the regression in #76244 seems to have originated from something measured by `stalled-cycles-backend`. I'll try to collect some finer-grained stats to see if I can isolate it. I wish I had a better idea of what was going on here. I'd like to prevent the regression from reappearing in the future due to small changes in unrelated code.
<details>
<summary>Current `master`:</summary>
```
Performance counter stats for 'cargo +baseline-stage1 check':
2,275.67 msec task-clock:u # 0.998 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
49,826 page-faults:u # 0.022 M/sec
5,117,221,678 cycles:u # 2.249 GHz
299,655,943 stalled-cycles-frontend:u # 5.86% frontend cycles idle
2,284,213,395 stalled-cycles-backend:u # 44.64% backend cycles idle
8,051,871,959 instructions:u # 1.57 insn per cycle
# 0.28 stalled cycles per insn
1,359,589,402 branches:u # 597.447 M/sec
7,359,347 branch-misses:u # 0.54% of all branches
2.281030026 seconds time elapsed
2.108197000 seconds user
0.164183000 seconds sys
```
</details>
<details>
<summary>Shrink `ParamEnv` without changing `IntRange::from_pat`:</summary>
```
Performance counter stats for 'cargo +perf-stage1 check':
2,751.79 msec task-clock:u # 0.996 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
50,103 page-faults:u # 0.018 M/sec
6,260,590,019 cycles:u # 2.275 GHz
317,355,920 stalled-cycles-frontend:u # 5.07% frontend cycles idle
3,397,743,582 stalled-cycles-backend:u # 54.27% backend cycles idle
8,276,224,367 instructions:u # 1.32 insn per cycle
# 0.41 stalled cycles per insn
1,370,453,386 branches:u # 498.023 M/sec
7,281,031 branch-misses:u # 0.53% of all branches
2.763265838 seconds time elapsed
2.544578000 seconds user
0.204548000 seconds sys
```
</details>
<details>
<summary>Shrink `ParamEnv` and change `IntRange::from_pat`: </summary>
```
Performance counter stats for 'cargo +perf-stage1 check':
2,295.57 msec task-clock:u # 0.996 CPUs utilized
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
49,959 page-faults:u # 0.022 M/sec
5,151,407,066 cycles:u # 2.244 GHz
324,517,829 stalled-cycles-frontend:u # 6.30% frontend cycles idle
2,301,671,001 stalled-cycles-backend:u # 44.68% backend cycles idle
8,130,868,329 instructions:u # 1.58 insn per cycle
# 0.28 stalled cycles per insn
1,356,618,512 branches:u # 590.972 M/sec
7,323,800 branch-misses:u # 0.54% of all branches
2.304509653 seconds time elapsed
2.128090000 seconds user
0.163909000 seconds sys
```
</details>
Makes progress towards #43081
In PR #73084, we started recursively expanded nonterminals during the
pretty-print/reparse check, allowing them to be properly compared
against the reparsed tokenstream.
Unfortunately, the recursive logic in that PR only handles the case
where a nonterminal appears inside a `TokenTree::Delimited`. If a
nonterminal appears directly in the expanded tokens of another
nonterminal, the inner nonterminal will not be expanded.
This PR fixes the recursive expansion of nonterminals, ensuring that
they are expanded wherever they occur.
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`
Previously, this method called the more general `pat_constructor`
function, which can return other pattern variants besides `IntRange`.
Then it throws away any non-`IntRange` variants. Specialize it so work
is only done when it could result in an `IntRange`.
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
```
