From 364b5f806ccc7f27e97caef6a5abf995fb6c2b7f Mon Sep 17 00:00:00 2001
From: Faith Ekstrand <faith.ekstrand@collabora.com>
Date: Wed, 3 Jun 2026 14:35:23 -0400
Subject: [PATCH] compiler/rust/smallvec: Optimize extend()

Reviewed-by: Mel Henning <mhenning@darkrefraction.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/42005>
---
 src/compiler/rust/smallvec.rs | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/compiler/rust/smallvec.rs b/src/compiler/rust/smallvec.rs
index 63c554dabd7..ba429b0a488 100644
--- a/src/compiler/rust/smallvec.rs
+++ b/src/compiler/rust/smallvec.rs
@@ -126,8 +126,22 @@ impl<T> Extend<T> for SmallVec<T> {
     where
         I: IntoIterator<Item = T>,
     {
-        for i in iter {
-            self.push(i)
+        let mut iter = iter.into_iter();
+        loop {
+            match &mut self.0 {
+                SmallVecImpl::None | SmallVecImpl::One(_) => {
+                    if let Some(i) = iter.next() {
+                        self.push(i);
+                    } else {
+                        // We ran out of items
+                        return;
+                    }
+                }
+                SmallVecImpl::Many(v) => {
+                    v.extend(iter);
+                    return;
+                }
+            }
         }
     }
 }