Abi::is_signed: assert that we are a Scalar
A bit more sanity checking, suggested by @eddyb. This makes this method actually "safer" than `TyS::is_signed`, so I made sure Miri consistently uses the `Abi` version.
Though I am not sure if this would have caught the mistake where the layout of a zero-sized enum was asked for its sign.
r? @eddyb
Optimize catch_unwind to match C++ try/catch
This refactors the implementation of catching unwinds to allow LLVM to inline the "try" closure directly into the happy path, avoiding indirection. This means that the catch_unwind implementation is (after this PR) zero-cost unless a panic is thrown.
https://rust.godbolt.org/z/cZcUSB is an example of the current codegen in a simple case. Notably, the codegen is *exactly the same* if `-Cpanic=abort` is passed, which is clearly not great.
This PR, on the other hand, generates the following assembly:
```asm
# -Cpanic=unwind:
push rbx
mov ebx,0x2a
call QWORD PTR [rip+0x1c53c] # <happy>
mov eax,ebx
pop rbx
ret
mov rdi,rax
call QWORD PTR [rip+0x1c537] # cleanup function call
call QWORD PTR [rip+0x1c539] # <unfortunate>
mov ebx,0xd
mov eax,ebx
pop rbx
ret
# -Cpanic=abort:
push rax
call QWORD PTR [rip+0x20a1] # <happy>
mov eax,0x2a
pop rcx
ret
```
Fixes#64224, and resolves#64222.
Rename rustc guide
This is in preparation for https://github.com/rust-lang/rustc-guide/issues/470
Needs to be merged after we actually rename the guide.
Have used this to rename:
`git grep -l 'rustc_guide' | xargs sed -i 's/rustc_guide/rustc_dev_guide/g'`
`git grep -l 'rustc-guide' | xargs sed -i 's/rustc-guide/rustc-dev-guide/g'`
`git grep -l 'rustc guide' | xargs sed -i 's/rustc guide/rustc dev guide/g'`
Added tvOS as targets
This is a first attempt of adding support tvOS as described in #48862. It's got a lot of overlap with [src/librustc_target/spec/apple_ios_base.rs](31dd4f4acb/src/librustc_target/spec/apple_ios_base.rs).
I thought about refactoring `apple_ios_base.rs` to include this as well but that would require each of the ios and tvos targets to be of the something like the form `let base = opts(AppleOS::TV, Arch::Arm64)?;` I also did the same thing for watchOS because from what I can tell, all three targets (iOS, tvOS, and watchOS) have the same logic but have different parameters being sent to `xcrun`. Thoughts?
As far as the `data_layout` and other parameters to `Target`, I did as much research as I could but it really seems that processor in the [iPhone 11 is the same as the apple TV](https://en.wikipedia.org/wiki/Apple-designed_processors) so I didn't change any of those parameters.
I did get this to build and tested that it's actually running the the below logic (because the parameter to `xcrun` is `appletvos` not `tvos`).
I didn't manage to get it to actually compile a file with `fn main(){}` because I don't have the stdlib for `aarch64-apple-tvos` compiled it seems. Is there documentation for this?
Similar to the ending of https://github.com/rust-lang/rust/pull/63467, I'm not sure what to do next.
Miri visitor: detect primitive types based on type, not layout (also, more tests)
I also converted the union-based transmutes to use `mem::transmute` for increased readability.
r? @eddyb @oli-obk
Adjust Miri value visitor, and doc-comment layout components
I realized that I still didn't have quite the right intuition for how our `LayoutDetails` work, so I had to adjust the Miri value visitor to the things I understood better now. I also added some doc-comments to `LayoutDetails` as a hopefully canonical place to note such things.
The main visitor change is that we *first* look at all the fields (according to `FieldPlacement`), and *then* check the variants and handle `Multiple` appropriately. I did not quite realize how orthogonal "fields" and "variants" are.
I also moved the check for the scalar ABI to *after* checking all the fields; this leads to better (more type-driven) error messages.
And it looks like we can finally remove that magic hack for `ty::Generator`. :D
r? @oli-obk for the Miri/visitor changes and @eddyb for the layout docs
The Miri PR is at: https://github.com/rust-lang/miri/pull/1178
Improve MinGW detection when cross compiling
Official mingw-w64 builds, MSYS2 and LLVM MinGW provide both `gcc.exe` and `$ARCH-w64-mingw32-gcc.exe` so they should not regress but I included CI changes to verify it though `@bors try` (I don't have permission).
This change will come handy when cross compiling from Linux or Cygwin since they use `gcc` as native compiler and `$ARCH-w64-mingw32-gcc.exe` for MinGW. This means users will no longer have to override the linker.
Remove unused feature gates
I think many of the remaining unstable things can be easily be replaced with stable things. I have kept the `#![feature(nll)]` even though it is only necessary in `libstd`, to make regressions of it harder.
