inlined_vector: optimize the move-assignment fast path.
We know that the elements are trivially destructible if this path is used, so
there is no need to call their destructors one by one.
PiperOrigin-RevId: 521088624
Change-Id: I3edff97a073770f99031eefa7a34968fad5d7880
diff --git a/absl/container/inlined_vector.h b/absl/container/inlined_vector.h
index 1d4878b..36327ad 100644
--- a/absl/container/inlined_vector.h
+++ b/absl/container/inlined_vector.h
@@ -831,14 +831,19 @@
friend H AbslHashValue(H h, const absl::InlinedVector<TheT, TheN, TheA>& a);
void MoveAssignment(MemcpyPolicy, InlinedVector&& other) {
- // TODO(b/274984172): we shouldn't need to do this, since we already know
- // the elements are trivially destructible when our move-assignment policy
- // is MemcpyPolicy.
- inlined_vector_internal::DestroyAdapter<A>::DestroyElements(
- storage_.GetAllocator(), data(), size());
- storage_.DeallocateIfAllocated();
- storage_.MemcpyFrom(other.storage_);
+ // Assumption check: we shouldn't be told to use memcpy to implement move
+ // asignment unless we have trivially destructible elements and an allocator
+ // that does nothing fancy.
+ static_assert(absl::is_trivially_destructible<value_type>::value, "");
+ static_assert(std::is_same<A, std::allocator<value_type>>::value, "");
+ // Throw away our existing heap allocation, if any. There is no need to
+ // destroy the existing elements one by one because we know they are
+ // trivially destructible.
+ storage_.DeallocateIfAllocated();
+
+ // Adopt the other vector's inline elements or heap allocation.
+ storage_.MemcpyFrom(other.storage_);
other.storage_.SetInlinedSize(0);
}
