Tweak inlining attributes for slice indexing

Doing some experiments in response to this unexpected regression: rust-lang#120863 (comment)

I expect the opt changes to be addressed by something like reviving rust-lang#91222. The debug changes are what I'm interested in.

Codegen tests will probably fail from time to time in this PR, I will fix them up later but also I don't trust the opt-level-z one: rust-lang#119878 (comment)

r? `@ghost`

…iler-errors

Ignore less tests in debug builds

Since rust-lang#120594 and rust-lang#120863, nearly all UB-detecting debug assertions get compiled out of code that is monomorphized by a crate built with debug assertions disabled.

Which means that if we default all our codegen tests to `-Cdebug-assertions=no`, most of them work just fine against a sysroot built with debug assertions.

I also tried to explain a bit better why some tests need to be skipped, for those that still need to be skipped.

Rollup merge of rust-lang#121531 - saethlin:ignore-less-debug, r=compiler-errors

Ignore less tests in debug builds

Since rust-lang#120594 and rust-lang#120863, nearly all UB-detecting debug assertions get compiled out of code that is monomorphized by a crate built with debug assertions disabled.

Which means that if we default all our codegen tests to `-Cdebug-assertions=no`, most of them work just fine against a sysroot built with debug assertions.

I also tried to explain a bit better why some tests need to be skipped, for those that still need to be skipped.

Upgrades the Rust toolchain to `nightly-2024-02-25`. The Rust compiler
PRs that triggered changes in this upgrades are:
 * rust-lang/rust#121209
 * rust-lang/rust#121309
 * rust-lang/rust#120863
 * rust-lang/rust#117772
 * rust-lang/rust#117658

With rust-lang/rust#121309 some intrinsics
became inlineable so their names became qualified. This made our `match`
on the intrinsic name to fail in those cases, leaving them as
unsupported constructs as in this example:

```
warning: Found the following unsupported constructs:
             - _RNvNtCscyGW2MM2t5j_4core10intrinsics8unlikelyCs1eohKeNmpdS_5arith (3)
             - caller_location (1)
             - foreign function (1)
         
         Verification will fail if one or more of these constructs is reachable.
         See https://model-checking.github.io/kani/rust-feature-support.html for more details.

[...]

Failed Checks: _RNvNtCscyGW2MM2t5j_4core10intrinsics8unlikelyCs1eohKeNmpdS_5arith is not currently supported by Kani. Please post your example at https://github.com/model-checking/kani/issues/new/choose
 File: "/home/ubuntu/.rustup/toolchains/nightly-2024-02-18-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/num/mod.rs", line 25, in core::num::<impl i8>::checked_add
```

We use `trimmed_name()` to work around this, but that may include type
arguments if the intrinsic is defined on generics. So in those cases, we
just take the first part of the name so we can keep the rest as before.

Resolves #3044

Use intrinsics::debug_assertions in debug_assert_nounwind

This is the first item in rust-lang/rust#120848.

Based on the benchmarking in this PR, it looks like, for the programs in our benchmark suite, enabling all these additional checks does not introduce significant compile-time overhead, with the single exception of `Alignment::new_unchecked`. Therefore, I've added `#[cfg(debug_assertions)]` to that one call site, so that it remains compiled out in the distributed standard library.

The trailing commas in the previous calls to `debug_assert_nounwind!` were causing the macro to expand to `panic_nouwnind_fmt`, which requires more work to set up its arguments, and that overhead alone is measured between this perf run and the next: rust-lang/rust#120863 (comment)

Use intrinsics::debug_assertions in debug_assert_nounwind

This is the first item in rust-lang/rust#120848.

Based on the benchmarking in this PR, it looks like, for the programs in our benchmark suite, enabling all these additional checks does not introduce significant compile-time overhead, with the single exception of `Alignment::new_unchecked`. Therefore, I've added `#[cfg(debug_assertions)]` to that one call site, so that it remains compiled out in the distributed standard library.

The trailing commas in the previous calls to `debug_assert_nounwind!` were causing the macro to expand to `panic_nouwnind_fmt`, which requires more work to set up its arguments, and that overhead alone is measured between this perf run and the next: rust-lang/rust#120863 (comment)