Raw strings (of all kinds) don't support escapes, so this function
should never be called on them.

It is used just once. With it removed, the relevant code is a little
boilerplate-y but much easier to read, and is the same length. Overall I
think it's an improvement.

This results in two non-generic types being used: `BorrowckResults` and
`BorrowckFlowState`. It's a net reduction in lines of code, and a little
easier to read.

`GenKillAnalysis` has five methods that take a transfer function arg:
- `statement_effect`
- `before_statement_effect`
- `terminator_effect`
- `before_terminator_effect`
- `call_return_effect`

All the transfer function args have type `&mut impl GenKill<Self::Idx>`,
except for `terminator_effect`, which takes the simpler `Self::Domain`.

But only the first two need to be `impl GenKill`. The other
three can all be `Self::Domain`, just like `Analysis`. So this commit
changes the last two to take `Self::Domain`, making `GenKillAnalysis`
and `Analysis` more similar.

(Another idea would be to make all these methods `impl GenKill`. But
that doesn't work: `MaybeInitializedPlaces::terminator_effect` requires
the arg be `Self::Domain` so that `self_is_unwind_dead(place, state)`
can be called on it.)

The fallback `_` case works for these chars, no need to treat them
specially.

These don't really make sense since C string literals were added. This
commit removes them in favour for `mode: Mode` args. `ascii_check` still
has a `characters_should_be_ascii: bool` arg.

Also, `characters_should_be_ascii` is renamed to be shorter.

The `empty!` macro calls should be outside the `cfg(FALSE)` function.

- Add `use Mode::*` to avoid all the qualifiers.
- Reorder the variants. The existing order makes no particular sense,
  which has bugged me for some time. I've chosen an order that makes
  sense to me.

as they unnecessarily clutter the diagnostic output and make the
experience of adding a new target to the compiler more painful than
it should be.

target_os and target_arch are still being tested in the
well-known-values.rs test, but in one place.

This maps to the LLVM intrinsics: llvm.masked.load and llvm.masked.store

…gjubilee

Add more SIMD platform-intrinsics

- [x] simd_masked_load
  - [x] LLVM codegen - llvm.masked.load
  - [x] cranelift codegen - implemented but untested
- [ ] simd_masked_store
  - [x] LLVM codegen - llvm.masked.store
  - [ ] cranelift codegen

Also added a run-pass test to test both intrinsics, and additional build-fail & check-fail to cover validation for both intrinsics

dedup for duplicate suggestions

Fixes rust-lang#118048

An easy fix.

…e, r=cjgillot

More `rustc_mir_dataflow` cleanups

r? `@cjgillot`

…own, r=nnethercote

Strengthen well known check-cfg names and values test

rust-lang#118494 is changing the implementation of how we expect well known check-cfg names and values, but we currently don't have a test that checks every well known only some of them.

This PR therefore strengthen our well known names/values test to include all of the configs to at least avoid unintended regressions and validate new entry.

*this PR also contains some drive-by consolidation of unexpected `target_os`, `target_arch` into a single file*

r? `@nnethercote` (maybe? feel free to re-assign)

…e1-dead

Unescaping cleanups

Minor improvements I found while working on rust-lang#118699.

r? `@fee1-dead`

…storino

Lower some forgotten spans

I wrote a HIR visitor that visited all of the spans in the HIR, and made it ICE when we have a unlowered span. That led me to discover these unlowered spans.