Auto merge of #77435 - hanmertens:binary_heap_append, r=scottmcm

Always use extend in BinaryHeap::append

This is faster, see #77433.

Fixes #77433

library/alloc/src/collections/binary_heap.rs

@@ -630,10 +630,16 @@ impl<T: Ord> BinaryHeap<T> {
  // and about 2 * (len1 + len2) comparisons in the worst case
  // while `extend` takes O(len2 * log(len1)) operations
  // and about 1 * len2 * log_2(len1) comparisons in the worst case,
- // assuming len1 >= len2.
+ // assuming len1 >= len2. For larger heaps, the crossover point
+ // no longer follows this reasoning and was determined empirically.
  #[inline]
  fn better_to_rebuild(len1: usize, len2: usize) -> bool {
- 2 * (len1 + len2) < len2 * log2_fast(len1)
+ let tot_len = len1 + len2;
+ if tot_len <= 2048 {
+ 2 * tot_len < len2 * log2_fast(len1)
+ } else {
+ 2 * tot_len < len2 * 11
+ }
  }
 
  if better_to_rebuild(self.len(), other.len()) {