Merge ref 'f53b654a8882' from rust-lang/rust

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: rust-lang/rust@f53b654
Filtered ref: 854e053
Upstream diff: rust-lang/rust@ca9a134...f53b654

This merge was created using https://github.com/rust-lang/josh-sync.

Author: The rustc-josh-sync Cronjob Bot

src/tests/compiletest.md

@@ -346,6 +346,17 @@ See also the [codegen tests](#codegen-tests) for a similar set of tests.
 If you need to work with `#![no_std]` cross-compiling tests, consult the
 [`minicore` test auxiliary](./minicore.md) chapter.
 
+#### Conditional assembly tests based on instruction support
+
+Tests that depend on specific assembly instructions being available can use the
+`//@ needs-asm-mnemonic: <MNEMONIC>` directive. This will skip the test if the
+target backend does not support the specified instruction mnemonic.
+
+For example, a test that requires the `RET` instruction:
+```rust,ignore
+//@ needs-asm-mnemonic: RET
+```
+
 [`tests/assembly-llvm`]: https://github.com/rust-lang/rust/tree/HEAD/tests/assembly-llvm
 
 

src/tests/directives.md

@@ -163,6 +163,9 @@ The following directives will check rustc build settings and target settings:
   For tests that cross-compile to explicit targets
   via `--target`, use `needs-llvm-components` instead to ensure the appropriate
   backend is available.
+- `needs-asm-mnemonic: <MNEMONIC>` — ignores if the target backend does not
+  support the specified assembly mnemonic (e.g., `RET`, `NOP`).
+  Only supported with the LLVM backend.
 - `needs-profiler-runtime` — ignores the test if the profiler runtime was not
   enabled for the target (`build.profiler = true` in `bootstrap.toml`)
 - `needs-sanitizer-support` — ignores if the sanitizer support was not enabled