bors [Tue, 27 Oct 2020 22:59:13 +0000 (22:59 +0000)]
Auto merge of #75671 - nathanwhit:cstring-temp-lint, r=oli-obk
Uplift `temporary-cstring-as-ptr` lint from `clippy` into rustc
The general consensus seems to be that this lint covers a common enough mistake to warrant inclusion in rustc.
The diagnostic message might need some tweaking, as I'm not sure the use of second-person perspective matches the rest of rustc, but I'd like to hear others' thoughts on that.
Ayrton [Tue, 6 Oct 2020 21:55:46 +0000 (17:55 -0400)]
Fixed compiler error in lint checker triggered by associated types
When a function argument bound by `Pointer` is an associated type, we only
perform substitutions using the parameters from the callsite but don't attempt
to normalize since it may not succeed. A simplified version of the scenario that
triggered this error was added as a test case. Also fixed `Pointer::fmt` which
was being double-counted when called outside of macros and added a test case for
this.
Ayrton [Tue, 6 Oct 2020 15:59:14 +0000 (11:59 -0400)]
Removed test for unhandled case in function_item_references lint
Removed test for the unhandled case of calls to `fn f<T>(x: &T)` where `x` is a
function reference and is formatted as a pointer in `f`. This compiles since
`&T` implements `Pointer`, but is unlikely to occur in practice. Also tweaked
the lint's wording and modified tests accordingly.
Ayrton [Tue, 6 Oct 2020 13:51:10 +0000 (09:51 -0400)]
Changed lint to check for `std::fmt::Pointer` and `transmute`
The lint checks arguments in calls to `transmute` or functions that have
`Pointer` as a trait bound and displays a warning if the argument is a function
reference. Also checks for `std::fmt::Pointer::fmt` to handle formatting macros
although it doesn't depend on the exact expansion of the macro or formatting
internals. `std::fmt::Pointer` and `std::fmt::Pointer::fmt` were also added as
diagnostic items and symbols.
Working with MIR let's us exclude expressions like `&fn_name as &dyn Something`
and `(&fn_name)()`. Also added ABI, unsafety and whether a function is variadic
in the lint suggestion, included the `&` in the span of the lint and updated the
test.
bors [Tue, 27 Oct 2020 11:43:18 +0000 (11:43 +0000)]
Auto merge of #78227 - SergioBenitez:test-stdout-threading, r=m-ou-se
Capture output from threads spawned in tests
This is revival of #75172.
Original text:
> Fixes #42474.
>
> r? `@dtolnay` since you expressed interest in this, but feel free to redirect if you aren't the right person anymore.
bors [Tue, 27 Oct 2020 09:25:54 +0000 (09:25 +0000)]
Auto merge of #77502 - varkor:const-generics-suggest-enclosing-braces, r=petrochenkov
Suggest that expressions that look like const generic arguments should be enclosed in brackets
I pulled out the changes for const expressions from https://github.com/rust-lang/rust/pull/71592 (without the trait object diagnostic changes) and made some small changes; the implementation is `@estebank's.`
We're also going to want to make some changes separately to account for trait objects (they result in poor diagnostics, as is evident from one of the test cases here), such as an adaption of https://github.com/rust-lang/rust/pull/72273.
Yuki Okushi [Mon, 26 Oct 2020 23:45:24 +0000 (08:45 +0900)]
Rollup merge of #78396 - josephlr:ermsb, r=petrochenkov
Add compiler support for LLVM's x86_64 ERMSB feature
This change is needed for compiler-builtins to check for this feature
when implementing memcpy/memset. See:
https://github.com/rust-lang/compiler-builtins/pull/365
Without this change, the following code compiles, but does nothing:
```rust
#[cfg(target_feature = "ermsb")]
pub unsafe fn ermsb_memcpy() { ... }
```
The change just does compile-time detection. I think that runtime
detection will have to come in a follow-up CL to std-detect.
Like all the CPU feature flags, this just references #44839
Yuki Okushi [Mon, 26 Oct 2020 23:44:57 +0000 (08:44 +0900)]
Rollup merge of #78342 - oliviacrain:checkmate-pass, r=Mark-Simulacrum
Use check-pass in single-use-lifetime ui tests
Rationale: the `single_use_lifetimes` lint is used during late name resolution, which is within the scope of `check-pass` and does not require codegen or linking.
Helps remove some FIXMES associated with #62277. Additionally tidies touched test files.
Yuki Okushi [Mon, 26 Oct 2020 23:44:41 +0000 (08:44 +0900)]
Rollup merge of #76635 - scottmcm:slice-as-chunks, r=LukasKalbertodt
Add [T]::as_chunks(_mut)
Allows getting the slices directly, rather than just through an iterator as in `array_chunks(_mut)`. The constructors for those iterators are then written in terms of these methods, so the iterator constructors no longer have any `unsafe` of their own.
bors [Mon, 26 Oct 2020 23:22:39 +0000 (23:22 +0000)]
Auto merge of #77876 - tmiasko:simplify-locals, r=wesleywiser
Remove unused set-discriminant statements and assignments regardless of rvalue
* Represent use counts with u32
* Unify use count visitors
* Change RemoveStatements visitor into a function
* Remove unused set-discriminant statements
* Use exhaustive match to clarify what is being optimized
* Remove unused assignments regardless of rvalue kind
bors [Mon, 26 Oct 2020 18:50:22 +0000 (18:50 +0000)]
Auto merge of #68965 - eddyb:mir-inline-scope, r=nagisa,oli-obk
rustc_mir: track inlined callees in SourceScopeData.
We now record which MIR scopes are the roots of *other* (inlined) functions's scope trees, which allows us to generate the correct debuginfo in codegen, similar to what LLVM inlining generates.
This PR makes the `ui` test `backtrace-debuginfo` pass, if the MIR inliner is turned on by default.
Also, `#[track_caller]` is now correct in the face of MIR inlining (cc `@anp).`
bors [Mon, 26 Oct 2020 16:31:38 +0000 (16:31 +0000)]
Auto merge of #77975 - bjorn3:cg_clif_subtree3, r=Mark-Simulacrum
Add cg_clif as optional codegen backend
Rustc_codegen_cranelift is an alternative codegen backend for rustc based on Cranelift. It has the potential to improve compilation times in debug mode. In my experience the compile time improvements over debug mode LLVM for a clean build are about 20-30% in most cases.
This PR adds cg_clif as optional codegen backend. By default it is only enabled for `./x.py check`. It can be enabled for `./x.py build` too by adding `cranelift` to the `rust.codegen-backends` array in `config.toml`.
bors [Mon, 26 Oct 2020 11:56:59 +0000 (11:56 +0000)]
Auto merge of #78196 - pietroalbini:shipped-files, r=Mark-Simulacrum
Allow creating a list of files shipped in a release
This PR adds the `BUILD_MANIFEST_SHIPPED_FILES_PATH` environment variable to `build-manifest`, which writes a list of all the files referenced in the manifest to the path defined in the variable. The use for this is for `promote-release` to prune files unused files before publishing a release.
This PR **does not implement any pruning**, it just adds support for it to be implemented in the future on `promote-release`'s side.
Joe Richey [Mon, 26 Oct 2020 10:46:54 +0000 (03:46 -0700)]
Add compiler support for LLVM's x86 ERMSB feature
This change is needed for compiler-builtins to check for this feature
when implementing memcpy/memset. See:
https://github.com/rust-lang/compiler-builtins/pull/365
The change just does compile-time detection. I think that runtime
detection will have to come in a follow-up CL to std-detect.
Like all the CPU feature flags, this just references #44839
Update affected ui & incremental tests to use a user declared variable
bindings instead of temporaries. The former are preserved because of
debuginfo, the latter are not.
Tomasz Miąsko [Thu, 22 Oct 2020 00:00:00 +0000 (00:00 +0000)]
simplify-locals: Unify use count visitors
The simplify locals implementation uses two different visitors to update
the locals use counts. The DeclMarker calculates the initial use counts.
The StatementDeclMarker updates the use counts as statements are being
removed from the block.
Replace them with a single visitor that can operate in either mode,
ensuring consistency of behaviour.
Additionally use exhaustive match to clarify what is being optimized.
This still looks very good, but LLVM does not really translate that to
what would be considered ideal machine code (on any target). For example
that's the codegen we obtain for an unknown alignment:
; x86_64
dec rsi
mov rax, rdi
neg rax
and rax, rsi
add rax, rdi
In particular negating a pointer is not something that’s going to be
optimised for in the design of CISC architectures like x86_64. They
are much better at offsetting pointers. And so we’d love to utilize this
ability and produce code that's more like this:
To achieve this we need to give LLVM an opportunity to apply its
various peep-hole optimisations that it does during DAG selection. In
particular, the `and` instruction appears to be a major inhibitor here.
We cannot, sadly, get rid of this load-bearing operation, but we can
reorder operations such that LLVM has more to work with around this
instruction.
One such ordering is proposed in #75579 and results in LLVM IR that
looks broadly like this:
; using add enables `lea` and similar CISCisms
%offset_ptr = add i64 %address, %a_minus_one
%mask = sub i64 0, %a
%masked = and i64 %offset_ptr, %mask
; can be folded with `gepi` that may follow
%offset = sub i64 %masked, %address
…and generates the intended x86_64 machine code.
One might also wonder how the increased amount of code would impact a
RISC target. Turns out not much:
; aarch64 previous ; aarch64 new
sub x8, x1, #1 add x8, x1, x0
neg x9, x0 sub x8, x8, #1
and x8, x9, x8 neg x9, x1
add x0, x0, x8 and x0, x8, x9
(and similarly for ppc, sparc, mips, riscv, etc)
The only target that seems to do worse is… wasm32.
Onto actual measurements – the best way to evaluate snipets like these
is to use llvm-mca. Much like Aarch64 assembly would allow to suspect,
there isn’t any performance difference to be found. Both snippets
execute in same number of cycles for the CPUs I tried. On x86_64,
we get throughput improvement of >50%!
bors [Mon, 26 Oct 2020 04:34:46 +0000 (04:34 +0000)]
Auto merge of #78387 - Dylan-DPC:rollup-ch0st6z, r=Dylan-DPC
Rollup of 10 pull requests
Successful merges:
- #74477 (`#[deny(unsafe_op_in_unsafe_fn)]` in sys/wasm)
- #77836 (transmute_copy: explain that alignment is handled correctly)
- #78126 (Properly define va_arg and va_list for aarch64-apple-darwin)
- #78137 (Initialize tracing subscriber in compiletest tool)
- #78161 (Add issue template link to IRLO)
- #78214 (Tweak match arm semicolon removal suggestion to account for futures)
- #78247 (Fix #78192)
- #78252 (Add codegen test for #45964)
- #78268 (Do not try to report on closures to avoid ICE)
- #78295 (Add some regression tests)
Dylan DPC [Mon, 26 Oct 2020 02:09:06 +0000 (03:09 +0100)]
Rollup merge of #78214 - estebank:match-semicolon, r=oli-obk
Tweak match arm semicolon removal suggestion to account for futures
* Tweak and extend "use `.await`" suggestions
* Suggest removal of semicolon on prior match arm
* Account for `impl Future` when suggesting semicolon removal
* Silence some errors when encountering `await foo()?` as can't be certain what the intent was
*Thanks to https://twitter.com/a_hoverbear/status/1318960787105353728 for pointing this out!*
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