A description of some of the recent changes to do allocations on the stack instead of the heap.

GoLang is an open-source programming language developed by Google, known for its simplicity, concurrency support, and performance. Developers can learn about GoLang's syntax, standard library, and concurrency primitives to build efficient and scalable software applications for various domains.

Go 1.25 and 1.26 introduce compiler optimizations that move slice allocations from the heap to the stack, reducing garbage collector pressure and improving performance. In Go 1.25, variable-sized make calls with small enough sizes are automatically backed by a 32-byte stack buffer. In Go 1.26, append-allocated slices also get a small speculative stack-allocated backing store, avoiding the startup-phase heap allocations (sizes 1, 2, 4, etc.). Additionally, for escaping slices, Go 1.26 automatically inserts a runtime.move2heap call so intermediate allocations stay on the stack and only one final heap allocation of the correct size is made. These changes reduce heap allocations and GC overhead without requiring code changes.

Allocating on the Stack

Stack allocation of constant-sized slices ¶

Stack allocation of variable-sized slices ¶

Stack allocation of append-allocated slices ¶

Stack allocation of append-allocated escaping slices ¶