Memory64

Memory64 allows memories and tables to use i64 indices instead of i32, expanding the addressable space from 4 GiB to 16 EiB.

(module
  ;; 64-bit addressed memory (1 page minimum)
  (memory $mem i64 1)

  (func (export "load64") (param $addr i64) (result i32)
    (i32.load (local.get $addr)))

  (func (export "size") (result i64)
    (memory.size))
)

When used with an i64-addressed memory:

• Memory instructions (i32.load, i64.store, etc.) accept i64 addresses
• memory.size and memory.grow return and accept i64 values
• Bulk memory operations (memory.copy, memory.fill, memory.init) use i64 for addresses and lengths
• Tables also support i64 indexing: (table $tbl i64 10 funcref)

Instruction Reference

• Memory Instructions — i32.load, i32.store, memory.size, memory.grow, memory.copy, memory.fill
• Table Instructions — table.get, table.set, table.size, table.grow