Rollup merge of #139675 - sayantn:avx10, r=Amanieu

Add the AVX10 target features

Parent #138843

Adds the `avx10_target_feature` feature gate, and `avx10.1` and `avx10.2` target features.

It is confirmed that Intel is dropping AVX10/256 (see [this comment](https://github.com/rust-lang/rust/issues/111137#issuecomment-2795442288)), so this should be safe to implement now.

The LLVM fix for llvm/llvm-project#135394 was merged, and has been backported to LLVM20, and the patch has also been propagated to rustc in #140502

`@rustbot` label O-x86_64 O-x86_32 A-target-feature A-SIMD

tests/ui/check-cfg/and-more-diagnostic.rs

@@ -5,7 +5,7 @@
 //@ no-auto-check-cfg
 //@ compile-flags: --check-cfg=cfg()
 //@ normalize-stderr: "and \d+ more" -> "and X more"
-//@ normalize-stderr: "`[a-zA-Z0-9_-]+`" -> "`xxx`"
+//@ normalize-stderr: "`[a-zA-Z0-9_\.-]+`" -> "`xxx`"
 
 fn main() {
     cfg!(target_feature = "zebra");

tests/ui/check-cfg/target_feature.stderr

@@ -29,6 +29,8 @@ LL |     cfg!(target_feature = "_UNEXPECTED_VALUE");
 `amx-transpose`
 `atomics`
 `avx`
+`avx10.1`
+`avx10.2`
 `avx2`
 `avx512bf16`
 `avx512bitalg`

tests/ui/feature-gates/feature-gate-avx10_target_feature.rs

@@ -0,0 +1,6 @@
+//@ only-x86_64
+#[target_feature(enable = "avx10.1")]
+//~^ ERROR: currently unstable
+unsafe fn foo() {}
+
+fn main() {}

tests/ui/feature-gates/feature-gate-avx10_target_feature.stderr

@@ -0,0 +1,13 @@
+error[E0658]: the target feature `avx10.1` is currently unstable
+  --> $DIR/feature-gate-avx10_target_feature.rs:2:18
+   |
+LL | #[target_feature(enable = "avx10.1")]
+   |                  ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #138843 <https://github.com/rust-lang/rust/issues/138843> for more information
+   = help: add `#![feature(avx10_target_feature)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0658`.