Remove `box_free` lang item

This PR removes the `box_free` lang item, replacing it with `Box`'s `Drop` impl. Box dropping is still slightly magic because the contained value is still dropped by the compiler.

…gcc-2023-06-19

Fix python linting errors

These were flagged by `ruff`, run using the config in rust-lang/rust#112482

Sync rustc_codegen_gcc 2023/06/19

Hi.
This is a sync of the rustc_codegen_gcc subtree.
Thanks.

This effectively inlines most of `FunctionCx::codegen_coverage` into the LLVM
implementation of `CoverageInfoBuilderMethods`.

…d it

These methods are only ever called from within `rustc_codegen_llvm`, so they
can just be declared there as well.

…ics.

LLVM has a neat [statistics] feature that tracks how often optimizations kick
in. It's very handy for optimization work. Since we expose the LLVM pass
timings, I thought it made sense to expose the LLVM statistics too.

[statistics]: https://llvm.org/docs/ProgrammersManual.html#the-statistic-class-stats-option

It replaces `(Linkage, Visibility)`, making the code nicer. Plus the
next commit will add another field.

Reduces error duplication and makes it more consistent across backends

Here I am assuming we want to treat these parameters (input, first, second, third, return) as translatable

…ull`

Resurrect: rustc_llvm: Add a -Z `print-codegen-stats` option to expose LLVM statistics.

This resurrects PR rust-lang/rust#104000, which has sat idle for a while. And I want to see the effect of stack-move optimizations on LLVM (like https://reviews.llvm.org/D153453) :).

I have applied the changes requested by `@oli-obk` and `@nagisa`  rust-lang/rust#104000 (comment) and rust-lang/rust#104000 (comment) in the latest commits.

r? `@oli-obk`

-----

LLVM has a neat [statistics](https://llvm.org/docs/ProgrammersManual.html#the-statistic-class-stats-option) feature that tracks how often optimizations kick in. It's very handy for optimization work. Since we expose the LLVM pass timings, I thought it made sense to expose the LLVM statistics too.

-----
(Edit: fix broken link
(Edit2: fix segmentation fault and use malloc

If `rustc` is built with
```toml
[llvm]
assertions = true
```
Then you can see like
```
rustc +stage1 -Z print-codegen-stats -C opt-level=3  tmp.rs
===-------------------------------------------------------------------------===
                          ... Statistics Collected ...
===-------------------------------------------------------------------------===
         3 aa                           - Number of MayAlias results
       193 aa                           - Number of MustAlias results
       531 aa                           - Number of NoAlias results
...
```

And the current default build emits only
```
$ rustc +stage1 -Z print-codegen-stats -C opt-level=3  tmp.rs
===-------------------------------------------------------------------------===
                          ... Statistics Collected ...
===-------------------------------------------------------------------------===
$
```
This might be better to emit the message to tell assertion flag necessity, but now I can't find how to do that...

Prototype: Add unstable `-Z reference-niches` option

MCP: rust-lang/compiler-team#641
Relevant RFC: rust-lang/rfcs#3204

This prototype adds a new `-Z reference-niches` option, controlling the range of valid bit-patterns for reference types (`&T` and `&mut T`), thereby enabling new enum niching opportunities. Like `-Z randomize-layout`, this setting is crate-local; as such, references to built-in types (primitives, tuples, ...) are not affected.

The possible settings are (here, `MAX` denotes the all-1 bit-pattern):
| `-Z reference-niches=` | Valid range |
|:---:|:---:|
| `null` (the default) | `1..=MAX` |
| `size` | `1..=(MAX- size)` |
| `align` | `align..=MAX.align_down_to(align)` |
| `size,align` | `align..=(MAX-size).align_down_to(align)` |

------

This is very WIP, and I'm not sure the approach I've taken here is the best one, but stage 1 tests pass locally; I believe this is in a good enough state to unleash this upon unsuspecting 3rd-party code, and see what breaks.

This reverts commit 557359f92512ca88b62a602ebda291f17a953002, reversing
changes made to 1e6c09a803fd543a98bfbe1624d697a55300a786.

…n-errors-in-gcc, r=davidtwco

Reuse `codegen_ssa` monomorphization errors in `codegen_gcc`

Removes monomorphization errors duplication by reusing the ones defined in `codegen_ssa`.

Also updates `expected_simd` errors usage in `codegen_gcc` by assuming we want to treat those parameters as translatable. See rust-lang/rust@7a888fb

cleanup: remove pointee types

This can't be merged until the oldest LLVM version we support uses opaque pointers, which will be the case after #114148. (Also note `-Cllvm-args="-opaque-pointers=0"` can technically be used in LLVM 15, though I don't think we should support that configuration.)

I initially hoped this would provide some minor perf win, but in rust-lang/rust#105412 (comment) it had very little impact, so this is only valuable as a cleanup.

As a followup, this will enable #96242 to be resolved.

r? `@ghost`

`@rustbot` label S-blocked

…rors

Fix ICE failed to get layout for ReferencesError

Fixes #114435

r? `@compiler-errors`

Co-authored-by: Ralf Jung <[email protected]>

Add a new `compare_bytes` intrinsic instead of calling `memcmp` directly

As discussed in #113435, this lets the backends be the place that can have the "don't call the function if n == 0" logic, if it's needed for the target.  (I didn't actually *add* those checks, though, since as I understood it we didn't actually need them on known targets?)

Doing this also let me make it `const` (unstable), which I don't think `extern "C" fn memcmp` can be.

cc `@RalfJung` `@Amanieu`