Auto merge of #155941 - JonathanBrouwer:rollup-Ak66iXR, r=JonathanBrouwer

Rollup of 15 pull requests

Successful merges:

 - rust-lang/rust#155923 (Subtree sync for rustc_codegen_cranelift)
 - rust-lang/rust#155930 (Sync from portable simd 2026 04 28)
 - rust-lang/rust#155850 (Only exclude the rust-lang/rust#155473 change for 1-byte bool-likes)
 - rust-lang/rust#151994 (switch to v0 mangling by default on stable)
 - rust-lang/rust#154325 (Tweak irrefutable let else warning output)
 - rust-lang/rust#155273 (Lock stable_crate_ids once in create_crate_num)
 - rust-lang/rust#155361 (Document that CFI diverges from Rust wrt. ABI-compatibility rules)
 - rust-lang/rust#155692 (disable naked-dead-code-elimination test if no RET mnemonic is available)
 - rust-lang/rust#155747 (Update documentation for `wasm32-wali-linux-musl` after integrating n…)
 - rust-lang/rust#155768 (compiletest: Overhaul the code for running an incremental test revision)
 - rust-lang/rust#155907 (Handle hkl const closures)
 - rust-lang/rust#155910 (misc stuff from reading borrowck again :))
 - rust-lang/rust#155913 (Delete the 12 year old fixme)
 - rust-lang/rust#155920 (remove review queue triagebot mentions)
 - rust-lang/rust#155936 (Rename `SharedContext::emit_dyn_lint*` into `emit_lint*`)

Author: bors

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