Function dynamic_extra_growth_unchanged_pointer

tests/all/memory.rs:455–506

(config: &mut Config)

#[wasmtime_test]
fn dynamic_extra_growth_unchanged_pointer(config: &mut Config) -> Result<()> {
    const EXTRA_PAGES: u64 = 5;
    config.memory_reservation(0);
    // 5 wasm pages extra
    config.memory_reservation_for_growth(EXTRA_PAGES * (1 << 16));
    let engine = Engine::new(&config)?;
    let mut store = Store::new(&engine, ());

    fn assert_behaves_well(store: &mut Store<()>, mem: &Memory) -> Result<()> {
        let ptr = mem.data_ptr(&store);

        // Each growth here should retain the same linear pointer in memory and the
        // memory shouldn't get moved.
        for _ in 0..EXTRA_PAGES {
            mem.grow(&mut *store, 1)?;
            assert_eq!(ptr, mem.data_ptr(&store));
        }

        // Growth afterwards though will be forced to move the pointer
        mem.grow(&mut *store, 1)?;
        let new_ptr = mem.data_ptr(&store);
        assert_ne!(ptr, new_ptr);

        for _ in 0..EXTRA_PAGES - 1 {
            mem.grow(&mut *store, 1)?;
            assert_eq!(new_ptr, mem.data_ptr(&store));
        }
        Ok(())
    }

    let mem = Memory::new(&mut store, MemoryType::new(10, None))?;
    assert_behaves_well(&mut store, &mem)?;

    let module = Module::new(&engine, r#"(module (memory (export "mem") 10))"#)?;
    let instance = Instance::new(&mut store, &module, &[])?;
    let mem = instance.get_memory(&mut store, "mem").unwrap();
    assert_behaves_well(&mut store, &mem)?;

    let module = Module::new(
        &engine,
        r#"
            (module
                (memory (export "mem") 10)
                (data (i32.const 0) ""))
        "#,
    )?;
    let instance = Instance::new(&mut store, &module, &[])?;
    let mem = instance.get_memory(&mut store, "mem").unwrap();
    assert_behaves_well(&mut store, &mem)?;

    Ok(())
}

// This test exercises trying to create memories of the maximum 64-bit memory
// size of `1 << 48` pages. This should always fail but in the process of