bhc-arena

Arena allocators for efficient compiler data structure allocation.

Overview

This crate provides arena allocators that enable fast allocation of compiler data structures with automatic bulk deallocation. Arenas are ideal for per-function or per-module compiler passes where many allocations have the same lifetime.

Key Types

Usage

use bhc_arena::Arena;

let arena = Arena::new();

// Allocate values - they live until the arena is dropped
let x = arena.alloc(42);
let y = arena.alloc("hello");

// Allocate slices
let slice = arena.alloc_slice(&[1, 2, 3, 4, 5]);

// Allocate from iterators
let from_iter = arena.alloc_from_iter(0..10);

// Track allocation statistics
println!("Bytes allocated: {}", arena.bytes_allocated());

Performance

Arena allocation is O(1) bump-pointer allocation, making it significantly faster than individual heap allocations for compiler workloads:

• Allocation: Simple pointer bump (no free-list traversal)
• Deallocation: Bulk free when arena is dropped (no per-object overhead)
• Cache locality: Sequential allocation improves cache behavior

When to Use

Design Notes

• Allocations from an arena MUST NOT outlive the arena
• The DroplessArena is more efficient for Copy types as it skips destructor tracking
• SyncArena uses internal locking and is safe for concurrent use

Related Crates

• bhc-intern - Uses arenas for string interning storage
• bhc-ast - Uses arenas for AST node allocation
• bhc-core - Uses arenas for Core IR allocation