[clang] [clang][docs] Document single-vector __builtin_shufflevector form (PR #214698)

[via cfe-commits]

https://github.com/richardmilles created https://github.com/llvm/llvm-project/pull/214698

Document that `__builtin_shufflevector` also accepts a single-vector form that only lists indices.

Fixes #59678


>From 16a32461f5bd1d53d2f00b03018f113f9005dc23 Mon Sep 17 00:00:00 2001
From: richardmilles <darkenhalneke at gmail.com>
Date: Fri, 7 Aug 2026 10:17:06 +0200
Subject: [PATCH] [clang][docs] Document single-vector __builtin_shufflevector
 form

Fixes #59678
---
 clang/docs/LanguageExtensions.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/docs/LanguageExtensions.md b/clang/docs/LanguageExtensions.md
index f5313e0378ca0..cda8d27875c42 100644
--- a/clang/docs/LanguageExtensions.md
+++ b/clang/docs/LanguageExtensions.md
@@ -3521,6 +3521,8 @@ for the implementation of various target-specific header files like
 
 ```c++
 __builtin_shufflevector(vec1, vec2, index1, index2, ...)
+
+Clang also accepts a single-vector form `__builtin_shufflevector(vec, index1, index2, ...)` that shuffles lanes within `vec` only.
 ```
 
 **Examples**: