This makes the output with `strip="symbols"` match the result of just
calling `strip` on the output binary, minimizing the size of the binary.

…raw-dylib")].

The metadata encoder does not necessarily encode all expansions, only
those which are referenced in other metadata fields.

This largely involves implementing the options debug-info-for-profiling
and profile-sample-use and forwarding them on to LLVM.

AutoFDO can be used on x86-64 Linux like this:
rustc -O -Cdebug-info-for-profiling main.rs -o main
perf record -b ./main
create_llvm_prof --binary=main --out=code.prof
rustc -O -Cprofile-sample-use=code.prof main.rs -o main2

Now `main2` will have feedback directed optimization applied to it.

The create_llvm_prof tool can be obtained from this github repository:
https://github.com/google/autofdo

Fixes rust-lang#64892.

The wrapper is installed as `ld` and `ld64` in the `lib\rustlib\<host_target>\bin\gcc-ld`
directory and its sole purpose is to invoke `rust-lld` in the parent directory with
the correct flavor.

Enable AutoFDO.

This largely involves implementing the options debug-info-for-profiling
and profile-sample-use and forwarding them on to LLVM.

AutoFDO can be used on x86-64 Linux like this:
rustc -O -Clink-arg='Wl,--no-rosegment' -Cdebug-info-for-profiling main.rs -o main
perf record -b ./main
create_llvm_prof --binary=main --out=code.prof
rustc -O -Cprofile-sample-use=code.prof main.rs -o main2

Now `main2` will have feedback directed optimization applied to it.

The create_llvm_prof tool can be obtained from this github repository:
https://github.com/google/autofdo

The option -Clink-arg='Wl,--no-rosegment' is necessary to avoid lld
putting an extra RO segment before the executable code, which would make
the binary silently incompatible with create_llvm_prof.

…ption, r=michaelwoerister

On macOS, make strip="symbols" not pass any options to strip

This makes the output with `strip="symbols"` match the result of just
calling `strip` on the output binary, minimizing the size of the binary.

…aahc

Fixed confusing wording on Result::map_or_else.

Fixes rust-lang#88195.

…ichaelwoerister

Implement `#[link_ordinal(n)]`

Allows the use of `#[link_ordinal(n)]` with `#[link(kind = "raw-dylib")]`, allowing Rust to link against DLLs that export symbols by ordinal rather than by name.  As long as the ordinal matches, the name of the function in Rust is not required to match the name of the corresponding function in the exporting DLL.

Part of rust-lang#58713.

Implement rust-lang#85440 (Random test ordering)

This PR adds `--shuffle` and `--shuffle-seed` options to `libtest`. The options are similar to the [`-shuffle` option](https://github.com/golang/go/blob/c894b442d1e5e150ad33fa3ce13dbfab1c037b3a/src/testing/testing.go#L1482-L1499) that was recently added to Go.

Here are the relevant parts of the help message:
```
        --shuffle       Run tests in random order
        --shuffle-seed SEED
                        Run tests in random order; seed the random number
                        generator with SEED
...
By default, the tests are run in alphabetical order. Use --shuffle or set
RUST_TEST_SHUFFLE to run the tests in random order. Pass the generated
"shuffle seed" to --shuffle-seed (or set RUST_TEST_SHUFFLE_SEED) to run the
tests in the same order again. Note that --shuffle and --shuffle-seed do not
affect whether the tests are run in parallel.
```
Is an RFC needed for this?

…ulacrum

Wrapper for `-Z gcc-ld=lld` to invoke rust-lld with the correct flavor

This PR adds an `lld-wrapper` tool which is installed as `ld` and `ld64` in `lib\rustlib\<host_target>\bin\gcc-ld` directory and whose sole purpose is to invoke `rust-lld` in the parent directory with the correct flavor. Lld decides which flavor to use from either the first two commandline arguments or from the name of the executable (`ld` for GNU/ld flavor, `ld64` for Darwin/Macos/ld64 flavor and so on). Symbolic links could not be used as they are not supported by rustup and on Windows.

The wrapper replaces full copies of rust-lld which added some significant bloat. On UNIXish operating systems it exec rust-lld, on Windows it spawns it as a child process.

Fixes rust-lang#88869.

r? ```@Mark-Simulacrum```
cc ```@nagisa``` ```@petrochenkov``` ```@1000teslas```

Correct decoding of foreign expansions during incr. comp.

Fixes rust-lang#74946

The original issue was due to a wrong assertion in `expn_hash_to_expn_id`.

The secondary issue was due to a mismatch between the encoding and decoding paths for expansions that are created after the TyCtxt is created.

Use correct edition for panic in [debug_]assert!().

See rust-lang#88638 (comment)