For E0277 on `for` loops, point at the "head" expression
When E0277's span points at a `for` loop, the actual issue is in the
element being iterated. Instead of pointing at the entire loop, point
only at the first line (when possible) so that the span ends in the
element for which E0277 was triggered.
Match libunwind's EABI selection with libpanic_unwind
Currently, the `libunwind` crate will only select the ARM EABI if it is compiling for ARM/Linux or Android targets. `libpanic_unwind`, however, will choose the ARM EABI if the target arch is ARM and the OS is not iOS. This means that if one tries to enable unwinding for a non-standard ARM target (such as implementing a custom stdlib via Xargo, for example), then the two crates can potentially disagree about which EABI is being targeted.
This PR makes `libunwind` use the [same logic](https://github.com/rust-lang/rust/blob/master/src/libpanic_unwind/gcc.rs#L139-L146) as `libpanic_unwind` when choosing the EABI.
I noticed there are a few comments about certain functions only differing on Android or ARM/Linux, but I *think* that those differences apply to the ARM EABI in general. Let me know if I'm wrong about that.
We can't use git commands to compute a prerelease version when we're
building from a source tarball, or if git is otherwise unavailable.
We'll just call such builds `x.y.z-beta`, without a prerelease.
First round of LLVM 6.0.0 compatibility
This includes a number of commits for the first round of upgrading to LLVM 6. There are still [lingering bugs](https://github.com/rust-lang/rust/issues/47683) but I believe all of this will nonetheless be necessary!
Fix ICE when use trees have multiple empty nested groups
The issue was caused by an oversight of mine in the original use_nested_groups PR, where different paths were resolved with the same `NodeId` in some cases (such as in `use {{}, {}};`).
Fixes#47673
r? @petrochenkov
do not ICE when return type includes unconstrained anon region
It turns out that this *can* happen after all, if the region is only
used in projections from the input types.
Fixes https://github.com/rust-lang/rust/issues/47511
r? @eddyb
[perf] Use std based dedup in projection
Unstable sort was added recently, and the code that is being modified is 3 years old. As quicksort doesn't allocate it will likely perform as well as, or better than linear search.
I didn't benchmark. Have a perf run.
Teach rustc about DW_AT_noreturn and a few more DIFlags
We achieve two small things with this PR:
1. We provide definitions for a few additional llvm debuginfo flags
1. We _use_ one of these new flags, `FlagNoReturn`, and add it to debuginfo for functions with the never return type (`!`).
This commit changes the ABI of SIMD types in the "Rust" ABI to unconditionally
be passed via pointers instead of being passed as immediates. This should fix a
longstanding issue, #44367, where SIMD-using programs ended up showing very odd
behavior at runtime because the ABI between functions was mismatched.
As a bit of a recap, this is sort of an LLVM bug and sort of an LLVM feature
(today's behavior). LLVM will generate code for a function solely looking at the
function it's generating, including calls to other functions. Let's then say
you've got something that looks like:
```llvm
define void @foo() { ; no target features enabled
call void @bar(<i64 x 4> zeroinitializer)
ret void
}
define void @bar(<i64 x 4>) #0 { ; enables the AVX feature
...
}
```
LLVM will codegen the call to `bar` *without* using AVX registers becauase `foo`
doesn't have access to these registers. Instead it's generated with emulation
that uses two 128-bit registers. The `bar` function, on the other hand, will
expect its argument in an AVX register (as it has AVX enabled). This means we've
got a codegen problem!
Comments on #44367 have some more contexutal information but the crux of the
issue is that if we want SIMD to work in general we'll need to ensure that
whenever a function calls another they ABI of the arguments being passed is in
agreement.
One possible solution to this would be to insert "shim functions" where whenever
a `target_feature` mismatch is detected the compiler inserts a shim function
where you pass arguments via memory to the shim and then the shim loads the
values and calls the target function (where the shim and the target have the
same target features enabled). This unfortunately is quite nontrivial to
implement in rustc today (especially when accounting for function pointers and
such).
This commit takes a different solution, *always* passing SIMD arguments through
memory instead of passing as immediates. This strategy solves the problem at the
LLVM layer because the ABI between two functions never uses SIMD registers. This
also shouldn't be a hit to performance because SIMD performance is thought to
often rely on inlining anyway, where a `call` instruction, even if using SIMD
registers, would be disastrous to performance regardless. LLVM should then be
more than capable of fixing all our memory usage to use registers instead after
enough inlining has been performed.
Note that there's a few caveats to this commit though:
* The "platform intrinsic" ABI is omitted from "always pass via memory". This
ABI is used to define intrinsics like `simd_shuffle4` where LLVM and rustc
need to have the arguments as an immediate.
* Additionally this commit does *not* fix the `extern` ("C") ABI. This means
that the bug in #44367 can still happen when using non-Rust-ABI functions. My
hope is that before stabilization we can ban and/or warn about SIMD types in
these functions (as AFAIK there's not much motivation to belong there anyway),
but I'll leave that for a later commit and if this is merged I'll file a
follow-up issue.
All in all this...
Closes#44367
Fix type inhabitedness check for arrays
Arrays of uninhabited types were considered to also be uninhabited if
their length had not been evaluated, causing unsoundness.
Fixes#47563.
r? @eddyb
Add ./x.py check src/{libstd,libtest,librustc}
This currently only supports a limited subset of the full compilation,
but is likely 90% of what people will want and is possible without
building a full compiler (and also building LLVM). In theory, this means
that contributors who don't want to build LLVM now have an easy way to
compile locally, though running tests won't work.
Fix no_integrated_as option to work with new codegen architecture.
Old implementation called the assembler once per crate, but we need to call
it for each object file instead, because a single crate can now have more
than one object file.
This patch fixes issue #45836 (Can't compile core for msp430 in release mode)
This change can be tested on x86_64 using
```sh
export RUSTFLAGS="-C no_integrated_as -C save_temps"
```
r? @alexcrichton
cc @japaric
