diff --git a/Cargo.lock b/Cargo.lock
index 9b0551916..cff878ec4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -489,15 +489,15 @@ dependencies = [
  "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "structopt 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "wabt 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasmer-clif-backend 0.1.0",
- "wasmer-emscripten 0.1.1",
- "wasmer-runtime 0.1.0",
- "wasmer-runtime-core 0.1.0",
+ "wasmer-clif-backend 0.2.0",
+ "wasmer-emscripten 0.2.0",
+ "wasmer-runtime 0.2.0",
+ "wasmer-runtime-core 0.2.0",
 ]
 
 [[package]]
 name = "wasmer-clif-backend"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
  "byteorder 1.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "cranelift-codegen 0.26.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -507,13 +507,13 @@ dependencies = [
  "hashbrown 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "nix 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "target-lexicon 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasmer-runtime-core 0.1.0",
+ "wasmer-runtime-core 0.2.0",
  "wasmparser 0.23.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "wasmer-emscripten"
-version = "0.1.1"
+version = "0.2.0"
 dependencies = [
  "byteorder 1.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -521,21 +521,21 @@ dependencies = [
  "libc 0.2.44 (git+https://github.com/rust-lang/libc)",
  "time 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)",
  "wabt 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasmer-clif-backend 0.1.0",
- "wasmer-runtime-core 0.1.0",
+ "wasmer-clif-backend 0.2.0",
+ "wasmer-runtime-core 0.2.0",
 ]
 
 [[package]]
 name = "wasmer-runtime"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
- "wasmer-clif-backend 0.1.0",
- "wasmer-runtime-core 0.1.0",
+ "wasmer-clif-backend 0.2.0",
+ "wasmer-runtime-core 0.2.0",
 ]
 
 [[package]]
 name = "wasmer-runtime-core"
-version = "0.1.0"
+version = "0.2.0"
 dependencies = [
  "errno 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "field-offset 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -543,7 +543,7 @@ dependencies = [
  "nix 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "page_size 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "wabt 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasmer-clif-backend 0.1.0",
+ "wasmer-clif-backend 0.2.0",
  "wasmparser 0.23.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
diff --git a/lib/clif-backend/src/module_env.rs b/lib/clif-backend/src/module_env.rs
index c396f7fd5..d9e1ba032 100644
--- a/lib/clif-backend/src/module_env.rs
+++ b/lib/clif-backend/src/module_env.rs
@@ -106,7 +106,7 @@ impl<'module, 'isa, 'data> ModuleEnvironment<'data> for ModuleEnv<'module, 'isa>
             GlobalInit::F32Const(x) => Initializer::Const(Value::F32(f32::from_bits(x))),
             GlobalInit::F64Const(x) => Initializer::Const(Value::F64(f64::from_bits(x))),
             GlobalInit::GetGlobal(global_index) => {
-                assert!(!desc.mutable);
+                // assert!(!desc.mutable); // Can be mutable
                 let global_index: GlobalIndex = Converter(global_index).into();
                 let imported_global_index = global_index
                     .local_or_import(self.module)
diff --git a/lib/emscripten/src/README.md b/lib/emscripten/src/README.md
index b88f1fc03..8bbc3b3b7 100644
--- a/lib/emscripten/src/README.md
+++ b/lib/emscripten/src/README.md
@@ -10,7 +10,7 @@
   ```
 - **abort** ✅ 🔥 &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
-  fn abort(message: u32, instance: &mut Instance)
+  fn abort(message: u32, vmctx: &mut Ctx)
   ```
 - **abort_on_cannot_grow_memory** ✅ &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
@@ -28,11 +28,11 @@
 
 - **\_getenv** ✅ &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
-  fn _getenv(name: c_int, instance: &mut Instance)
+  fn _getenv(name: c_int, vmctx: &mut Ctx)
   ```
 - **\_putenv** ✅ &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
-  fn _putenv(name: c_int, instance: &mut Instance)
+  fn _putenv(name: c_int, vmctx: &mut Ctx)
   ```
 - **\_setenv** ✅ &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
@@ -40,7 +40,7 @@
   ```
 - **\_unsetenv** ✅ &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
-  fn _unsetenv(name: c_int, instance: &mut Instance)
+  fn _unsetenv(name: c_int, vmctx: &mut Ctx)
   ```
 
 ###### THREAD
@@ -70,7 +70,7 @@
 
 - **\_emscripten_memcpy_big** ✅ 🔥 &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
-  fn _emscripten_memcpy_big(dest: u32, src: u32, len: u32, instance: &mut Instance) -> u32
+  fn _emscripten_memcpy_big(dest: u32, src: u32, len: u32, vmctx: &mut Ctx) -> u32
   ```
 - **enlarge_memory** ✅ &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
@@ -78,7 +78,7 @@
   ```
 - **get_total_memory** ✅ &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
-  fn get_total_memory(instance: &mut Instance) -> u32
+  fn get_total_memory(vmctx: &mut Ctx) -> u32
   ```
 
 ###### TIMING
@@ -337,7 +337,7 @@
   ```
 - **open** (\_\_\_syscall5) ✅ ❗️ 🔥 &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
-  fn open(path: u32, flags: c_int, mode: c_int, instance: &mut Instance) -> c_int
+  fn open(path: u32, flags: c_int, mode: c_int, vmctx: &mut Ctx) -> c_int
   ```
 - **openat** (\_\_\_syscall295) &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
@@ -385,7 +385,7 @@
   ```
 - **read** (\_\_\_syscall3) ✅ ❗️ &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
-  fn read(fd: c_int, buf: u32, count: size_t, instance: &mut Instance) -> ssize_t
+  fn read(fd: c_int, buf: u32, count: size_t, vmctx: &mut Ctx) -> ssize_t
   ```
 - **readlink** (\_\_\_syscall85) &nbsp;&nbsp;&nbsp;&nbsp;[:top:](#host-apis)
   ```rust
diff --git a/lib/emscripten/src/env.rs b/lib/emscripten/src/env.rs
index 65c9d9520..df1c624eb 100644
--- a/lib/emscripten/src/env.rs
+++ b/lib/emscripten/src/env.rs
@@ -8,7 +8,7 @@ use std::mem;
 use std::os::raw::c_char;
 
 use super::utils::{allocate_on_stack, copy_cstr_into_wasm, copy_terminated_array_of_cstrs};
-use wasmer_runtime_core::{types::Value, Instance};
+use wasmer_runtime_core::{types::Value, vm::Ctx};
 //use super::EmscriptenData;
 
 //impl Instance {
@@ -23,10 +23,10 @@ use wasmer_runtime_core::{types::Value, Instance};
 
 // #[no_mangle]
 /// emscripten: _getenv // (name: *const char) -> *const c_char;
-pub extern "C" fn _getenv(name: c_int, instance: &mut Instance) -> u32 {
+pub extern "C" fn _getenv(name: c_int, vmctx: &mut Ctx) -> u32 {
     debug!("emscripten::_getenv");
 
-    let name_addr = instance.memory_offset_addr(0, name as usize) as *const c_char;
+    let name_addr = vmctx.memory(0)[name as usize] as *const c_char;
 
     debug!("=> name({:?})", unsafe { CStr::from_ptr(name_addr) });
 
@@ -35,15 +35,15 @@ pub extern "C" fn _getenv(name: c_int, instance: &mut Instance) -> u32 {
         return 0;
     }
 
-    unsafe { copy_cstr_into_wasm(instance, c_str) }
+    unsafe { copy_cstr_into_wasm(vmctx, c_str) }
 }
 
 /// emscripten: _setenv // (name: *const char, name: *const value, overwrite: int);
-pub extern "C" fn _setenv(name: c_int, value: c_int, overwrite: c_int, instance: &mut Instance) {
+pub extern "C" fn _setenv(name: c_int, value: c_int, overwrite: c_int, vmctx: &mut Ctx) {
     debug!("emscripten::_setenv");
 
-    let name_addr = instance.memory_offset_addr(0, name as usize) as *const c_char;
-    let value_addr = instance.memory_offset_addr(0, value as usize) as *const c_char;
+    let name_addr = vmctx.memory(0)[name as usize] as *const c_char;
+    let value_addr = vmctx.memory(0)[value as usize] as *const c_char;
 
     debug!("=> name({:?})", unsafe { CStr::from_ptr(name_addr) });
     debug!("=> value({:?})", unsafe { CStr::from_ptr(value_addr) });
@@ -52,10 +52,10 @@ pub extern "C" fn _setenv(name: c_int, value: c_int, overwrite: c_int, instance:
 }
 
 /// emscripten: _putenv // (name: *const char);
-pub extern "C" fn _putenv(name: c_int, instance: &mut Instance) {
+pub extern "C" fn _putenv(name: c_int, vmctx: &mut Ctx) {
     debug!("emscripten::_putenv");
 
-    let name_addr = instance.memory_offset_addr(0, name as usize) as *const c_char;
+    let name_addr = vmctx.memory(0)[name as usize] as *const c_char;
 
     debug!("=> name({:?})", unsafe { CStr::from_ptr(name_addr) });
 
@@ -63,10 +63,10 @@ pub extern "C" fn _putenv(name: c_int, instance: &mut Instance) {
 }
 
 /// emscripten: _unsetenv // (name: *const char);
-pub extern "C" fn _unsetenv(name: c_int, instance: &mut Instance) {
+pub extern "C" fn _unsetenv(name: c_int, vmctx: &mut Ctx) {
     debug!("emscripten::_unsetenv");
 
-    let name_addr = instance.memory_offset_addr(0, name as usize) as *const c_char;
+    let name_addr = vmctx.memory(0)[name as usize] as *const c_char;
 
     debug!("=> name({:?})", unsafe { CStr::from_ptr(name_addr) });
 
@@ -74,7 +74,7 @@ pub extern "C" fn _unsetenv(name: c_int, instance: &mut Instance) {
 }
 
 #[allow(clippy::cast_ptr_alignment)]
-pub extern "C" fn _getpwnam(name_ptr: c_int, instance: &mut Instance) -> c_int {
+pub extern "C" fn _getpwnam(name_ptr: c_int, vmctx: &mut Ctx) -> c_int {
     debug!("emscripten::_getpwnam {}", name_ptr);
 
     #[repr(C)]
@@ -89,21 +89,20 @@ pub extern "C" fn _getpwnam(name_ptr: c_int, instance: &mut Instance) -> c_int {
     }
 
     let name = unsafe {
-        let memory_name_ptr = instance.memory_offset_addr(0, name_ptr as usize) as *const c_char;
+        let memory_name_ptr = vmctx.memory(0)[name_ptr as usize] as *const c_char;
         CStr::from_ptr(memory_name_ptr)
     };
 
     unsafe {
         let passwd = &*libc_getpwnam(name.as_ptr());
-        let passwd_struct_offset = call_malloc(mem::size_of::<GuestPasswd>() as _, instance);
+        let passwd_struct_offset = call_malloc(mem::size_of::<GuestPasswd>() as _, vmctx);
 
-        let passwd_struct_ptr =
-            instance.memory_offset_addr(0, passwd_struct_offset as _) as *mut GuestPasswd;
-        (*passwd_struct_ptr).pw_name = copy_cstr_into_wasm(instance, passwd.pw_name);
-        (*passwd_struct_ptr).pw_passwd = copy_cstr_into_wasm(instance, passwd.pw_passwd);
-        (*passwd_struct_ptr).pw_gecos = copy_cstr_into_wasm(instance, passwd.pw_gecos);
-        (*passwd_struct_ptr).pw_dir = copy_cstr_into_wasm(instance, passwd.pw_dir);
-        (*passwd_struct_ptr).pw_shell = copy_cstr_into_wasm(instance, passwd.pw_shell);
+        let passwd_struct_ptr = vmctx.memory(0)[passwd_struct_offset as usize] as *mut GuestPasswd;
+        (*passwd_struct_ptr).pw_name = copy_cstr_into_wasm(vmctx, passwd.pw_name);
+        (*passwd_struct_ptr).pw_passwd = copy_cstr_into_wasm(vmctx, passwd.pw_passwd);
+        (*passwd_struct_ptr).pw_gecos = copy_cstr_into_wasm(vmctx, passwd.pw_gecos);
+        (*passwd_struct_ptr).pw_dir = copy_cstr_into_wasm(vmctx, passwd.pw_dir);
+        (*passwd_struct_ptr).pw_shell = copy_cstr_into_wasm(vmctx, passwd.pw_shell);
         (*passwd_struct_ptr).pw_uid = passwd.pw_uid;
         (*passwd_struct_ptr).pw_gid = passwd.pw_gid;
 
@@ -112,7 +111,7 @@ pub extern "C" fn _getpwnam(name_ptr: c_int, instance: &mut Instance) -> c_int {
 }
 
 #[allow(clippy::cast_ptr_alignment)]
-pub extern "C" fn _getgrnam(name_ptr: c_int, instance: &mut Instance) -> c_int {
+pub extern "C" fn _getgrnam(name_ptr: c_int, vmctx: &mut Ctx) -> c_int {
     debug!("emscripten::_getgrnam {}", name_ptr);
 
     #[repr(C)]
@@ -124,66 +123,69 @@ pub extern "C" fn _getgrnam(name_ptr: c_int, instance: &mut Instance) -> c_int {
     }
 
     let name = unsafe {
-        let memory_name_ptr = instance.memory_offset_addr(0, name_ptr as usize) as *const c_char;
+        let memory_name_ptr = vmctx.memory(0)[name_ptr as usize] as *const c_char;
         CStr::from_ptr(memory_name_ptr)
     };
 
     unsafe {
         let group = &*libc_getgrnam(name.as_ptr());
-        let group_struct_offset = call_malloc(mem::size_of::<GuestGroup>() as _, instance);
+        let group_struct_offset = call_malloc(mem::size_of::<GuestGroup>() as _, vmctx);
 
-        let group_struct_ptr =
-            instance.memory_offset_addr(0, group_struct_offset as _) as *mut GuestGroup;
-        (*group_struct_ptr).gr_name = copy_cstr_into_wasm(instance, group.gr_name);
-        (*group_struct_ptr).gr_passwd = copy_cstr_into_wasm(instance, group.gr_passwd);
+        let group_struct_ptr = vmctx.memory(0)[group_struct_offset as usize] as *mut GuestGroup;
+        (*group_struct_ptr).gr_name = copy_cstr_into_wasm(vmctx, group.gr_name);
+        (*group_struct_ptr).gr_passwd = copy_cstr_into_wasm(vmctx, group.gr_passwd);
         (*group_struct_ptr).gr_gid = group.gr_gid;
-        (*group_struct_ptr).gr_mem = copy_terminated_array_of_cstrs(instance, group.gr_mem);
+        (*group_struct_ptr).gr_mem = copy_terminated_array_of_cstrs(vmctx, group.gr_mem);
 
         group_struct_offset as c_int
     }
 }
 
-pub fn call_malloc(size: i32, instance: &mut Instance) -> u32 {
-    let ret = instance
-        .call("_malloc", &[Value::I32(size)])
-        .expect("_malloc call failed");
-    if let [Value::I32(x)] = ret.as_slice() {
-        *x as u32
-    } else {
-        panic!("unexpected value from _malloc: {:?}", ret);
-    }
+pub fn call_malloc(size: i32, vmctx: &mut Ctx) -> u32 {
+    unimplemented!()
+//    let ret = instance
+//        .call("_malloc", &[Value::I32(size)])
+//        .expect("_malloc call failed");
+//    if let [Value::I32(x)] = ret.as_slice() {
+//        *x as u32
+//    } else {
+//        panic!("unexpected value from _malloc: {:?}", ret);
+//    }
 }
 
-pub fn call_memalign(alignment: u32, size: u32, instance: &mut Instance) -> u32 {
-    let ret = instance
-        .call(
-            "_memalign",
-            &[Value::I32(alignment as i32), Value::I32(size as i32)],
-        )
-        .expect("_memalign call failed");
-    if let [Value::I32(x)] = ret.as_slice() {
-        *x as u32
-    } else {
-        panic!("unexpected value from _memalign {:?}", ret);
-    }
+pub fn call_memalign(alignment: u32, size: u32, vmctx: &mut Ctx) -> u32 {
+    unimplemented!()
+    // let ret =
+    //     call(
+    //         vmctx,
+    //         "_memalign",
+    //         &[Value::I32(alignment as i32), Value::I32(size as i32)],
+    //     )
+    //     .expect("_memalign call failed");
+    // if let [Value::I32(x)] = ret.as_slice() {
+    //     *x as u32
+    // } else {
+    //     panic!("unexpected value from _memalign {:?}", ret);
+    // }
 }
 
-pub fn call_memset(pointer: u32, value: i32, size: u32, instance: &mut Instance) -> u32 {
-    let ret = instance
-        .call(
-            "_memset",
-            &[
-                Value::I32(pointer as i32),
-                Value::I32(value),
-                Value::I32(size as i32),
-            ],
-        )
-        .expect("_memset call failed");
-    if let [Value::I32(x)] = ret.as_slice() {
-        *x as u32
-    } else {
-        panic!("unexpected value from _memset {:?}", ret);
-    }
+pub fn call_memset(pointer: u32, value: i32, size: u32, vmctx: &mut Ctx) -> u32 {
+    unimplemented!()
+//    let ret = instance
+//        .call(
+//            "_memset",
+//            &[
+//                Value::I32(pointer as i32),
+//                Value::I32(value),
+//                Value::I32(size as i32),
+//            ],
+//        )
+//        .expect("_memset call failed");
+//    if let [Value::I32(x)] = ret.as_slice() {
+//        *x as u32
+//    } else {
+//        panic!("unexpected value from _memset {:?}", ret);
+//    }
 }
 
 pub extern "C" fn _getpagesize() -> u32 {
@@ -192,18 +194,18 @@ pub extern "C" fn _getpagesize() -> u32 {
 }
 
 #[allow(clippy::cast_ptr_alignment)]
-pub extern "C" fn ___build_environment(environ: c_int, instance: &mut Instance) {
+pub extern "C" fn ___build_environment(environ: c_int, vmctx: &mut Ctx) {
     debug!("emscripten::___build_environment {}", environ);
     const MAX_ENV_VALUES: u32 = 64;
     const TOTAL_ENV_SIZE: u32 = 1024;
-    let mut environment = instance.memory_offset_addr(0, environ as _) as *mut c_int;
+    let mut environment = vmctx.memory(0)[environ as usize] as *mut c_int;
     unsafe {
         let (pool_offset, _pool_slice): (u32, &mut [u8]) =
-            allocate_on_stack(TOTAL_ENV_SIZE as u32, instance);
+            allocate_on_stack(TOTAL_ENV_SIZE as u32, vmctx);
         let (env_offset, _env_slice): (u32, &mut [u8]) =
-            allocate_on_stack((MAX_ENV_VALUES * 4) as u32, instance);
-        let mut env_ptr = instance.memory_offset_addr(0, env_offset as _) as *mut c_int;
-        let mut _pool_ptr = instance.memory_offset_addr(0, pool_offset as _) as *mut c_int;
+            allocate_on_stack((MAX_ENV_VALUES * 4) as u32, vmctx);
+        let mut env_ptr = vmctx.memory(0)[env_offset as usize] as *mut c_int;
+        let mut _pool_ptr = vmctx.memory(0)[pool_offset as usize] as *mut c_int;
         *env_ptr = pool_offset as i32;
         *environment = env_offset as i32;
 
@@ -214,7 +216,7 @@ pub extern "C" fn ___build_environment(environ: c_int, instance: &mut Instance)
     // };
 }
 
-pub extern "C" fn _sysconf(name: c_int, _instance: &mut Instance) -> c_long {
+pub extern "C" fn _sysconf(name: c_int, _vmctx: &mut Ctx) -> c_long {
     debug!("emscripten::_sysconf {}", name);
     // TODO: Implement like emscripten expects regarding memory/page size
     unsafe { sysconf(name) }
diff --git a/lib/emscripten/src/exception.rs b/lib/emscripten/src/exception.rs
index 418ef6501..cf8a12ea6 100644
--- a/lib/emscripten/src/exception.rs
+++ b/lib/emscripten/src/exception.rs
@@ -1,16 +1,16 @@
 use super::env;
 use super::process::_abort;
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::{Instance, vm::Ctx};
 
 /// emscripten: ___cxa_allocate_exception
-pub extern "C" fn ___cxa_allocate_exception(size: u32, instance: &mut Instance) -> u32 {
+pub extern "C" fn ___cxa_allocate_exception(size: u32, vmctx: &mut Ctx) -> u32 {
     debug!("emscripten::___cxa_allocate_exception");
-    env::call_malloc(size as _, instance)
+    env::call_malloc(size as _, vmctx)
 }
 
 /// emscripten: ___cxa_throw
 /// TODO: We don't have support for exceptions yet
-pub extern "C" fn ___cxa_throw(_ptr: u32, ty: u32, destructor: u32, instance: &mut Instance) {
+pub extern "C" fn ___cxa_throw(_ptr: u32, ty: u32, destructor: u32, vmctx: &mut Ctx) {
     debug!("emscripten::___cxa_throw");
     _abort();
 }
diff --git a/lib/emscripten/src/jmp.rs b/lib/emscripten/src/jmp.rs
index eb28a68c5..87d105546 100644
--- a/lib/emscripten/src/jmp.rs
+++ b/lib/emscripten/src/jmp.rs
@@ -1,15 +1,15 @@
 use libc::{c_int, c_void};
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::vm::Ctx;
 
 /// setjmp
-pub extern "C" fn __setjmp(env_addr: u32, instance: &mut Instance) -> c_int {
+pub extern "C" fn __setjmp(env_addr: u32, vmctx: &mut Ctx) -> c_int {
     debug!("emscripten::__setjmp (setjmp)");
     unimplemented!()
     //    unsafe {
     //        // Rather than using the env as the holder of the jump buffer pointer,
     //        // we use the environment address to store the index relative to jumps
     //        // so the address of the jump it's outside the wasm memory itself.
-    //        let jump_index = instance.memory_offset_addr(0, env_addr as usize) as *mut i8;
+    //        let jump_index = vmctx.memory(0)[env_addr as usize] as *mut i8;
     //        // We create the jump buffer outside of the wasm memory
     //        let jump_buf: UnsafeCell<[c_int; 27]> = UnsafeCell::new([0; 27]);
     //        let mut jumps = &mut instance.emscripten_data().as_mut().unwrap().jumps;
@@ -23,12 +23,12 @@ pub extern "C" fn __setjmp(env_addr: u32, instance: &mut Instance) -> c_int {
 }
 
 /// longjmp
-pub extern "C" fn __longjmp(env_addr: u32, val: c_int, instance: &mut Instance) -> ! {
+pub extern "C" fn __longjmp(env_addr: u32, val: c_int, vmctx: &mut Ctx) -> ! {
     debug!("emscripten::__longjmp (longjmp) {}", val);
     unimplemented!()
     //    unsafe {
     //        // We retrieve the jump index from the env address
-    //        let jump_index = instance.memory_offset_addr(0, env_addr as usize) as *mut i8;
+    //        let jump_index = vmctx.memory(0)[env_addr as usize] as *mut i8;
     //        let mut jumps = &mut instance.emscripten_data().as_mut().unwrap().jumps;
     //        // We get the real jump buffer from the jumps vector, using the retrieved index
     //        let mut jump_buf = &jumps[*jump_index as usize];
diff --git a/lib/emscripten/src/lock.rs b/lib/emscripten/src/lock.rs
index 7a8ec9cb1..17073b591 100644
--- a/lib/emscripten/src/lock.rs
+++ b/lib/emscripten/src/lock.rs
@@ -1,17 +1,17 @@
 use libc::c_int;
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::vm::Ctx;
 
 // NOTE: Not implemented by Emscripten
-pub extern "C" fn ___lock(which: c_int, varargs: c_int, _instance: &mut Instance) {
+pub extern "C" fn ___lock(which: c_int, varargs: c_int, _vmctx: &mut Ctx) {
     debug!("emscripten::___lock {}, {}", which, varargs);
 }
 
 // NOTE: Not implemented by Emscripten
-pub extern "C" fn ___unlock(which: c_int, varargs: c_int, _instance: &mut Instance) {
+pub extern "C" fn ___unlock(which: c_int, varargs: c_int, _vmctx: &mut Ctx) {
     debug!("emscripten::___unlock {}, {}", which, varargs);
 }
 
 // NOTE: Not implemented by Emscripten
-pub extern "C" fn ___wait(_which: c_int, _varargs: c_int, _instance: &mut Instance) {
+pub extern "C" fn ___wait(_which: c_int, _varargs: c_int, _vmctx: &mut Ctx) {
     debug!("emscripten::___wait");
 }
diff --git a/lib/emscripten/src/memory.rs b/lib/emscripten/src/memory.rs
index c59af6317..7e48e0144 100644
--- a/lib/emscripten/src/memory.rs
+++ b/lib/emscripten/src/memory.rs
@@ -1,20 +1,15 @@
 use super::process::abort_with_message;
 use libc::{c_int, c_void, memcpy, size_t};
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::vm::Ctx;
 
 /// emscripten: _emscripten_memcpy_big
-pub extern "C" fn _emscripten_memcpy_big(
-    dest: u32,
-    src: u32,
-    len: u32,
-    instance: &mut Instance,
-) -> u32 {
+pub extern "C" fn _emscripten_memcpy_big(dest: u32, src: u32, len: u32, vmctx: &mut Ctx) -> u32 {
     debug!(
         "emscripten::_emscripten_memcpy_big {}, {}, {}",
         dest, src, len
     );
-    let dest_addr = instance.memory_offset_addr(0, dest as usize) as *mut c_void;
-    let src_addr = instance.memory_offset_addr(0, src as usize) as *mut c_void;
+    let dest_addr = vmctx.memory(0)[dest as usize] as *mut c_void;
+    let src_addr = vmctx.memory(0)[src as usize] as *mut c_void;
     unsafe {
         memcpy(dest_addr, src_addr, len as size_t);
     }
@@ -22,16 +17,18 @@ pub extern "C" fn _emscripten_memcpy_big(
 }
 
 /// emscripten: getTotalMemory
-pub extern "C" fn get_total_memory(_instance: &mut Instance) -> u32 {
+pub extern "C" fn get_total_memory(_vmctx: &mut Ctx) -> u32 {
     debug!("emscripten::get_total_memory");
     // instance.memories[0].current_pages()
+    // TODO: Fix implementation
     16_777_216
 }
 
 /// emscripten: enlargeMemory
-pub extern "C" fn enlarge_memory(_instance: &mut Instance) {
+pub extern "C" fn enlarge_memory(_vmctx: &mut Ctx) {
     debug!("emscripten::enlarge_memory");
     // instance.memories[0].grow(100);
+    // TODO: Fix implementation
 }
 
 /// emscripten: abortOnCannotGrowMemory
diff --git a/lib/emscripten/src/nullfunc.rs b/lib/emscripten/src/nullfunc.rs
index 3cfc44bdd..3121b094a 100644
--- a/lib/emscripten/src/nullfunc.rs
+++ b/lib/emscripten/src/nullfunc.rs
@@ -1,62 +1,62 @@
 use super::process::abort_with_message;
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::vm::Ctx;
 
-pub extern "C" fn nullfunc_ii(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_ii(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_ii {}", x);
     abort_with_message("Invalid function pointer called with signature 'ii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_iii(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_iii(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_iii {}", x);
     abort_with_message("Invalid function pointer called with signature 'iii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_iiii(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_iiii(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_iiii {}", x);
     abort_with_message("Invalid function pointer called with signature 'iiii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_iiiii(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_iiiii(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_iiiii {}", x);
     abort_with_message("Invalid function pointer called with signature 'iiiii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_iiiiii(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_iiiiii(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_iiiiii {}", x);
     abort_with_message("Invalid function pointer called with signature 'iiiiii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_v(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_v(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_v {}", x);
     abort_with_message("Invalid function pointer called with signature 'v'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_vi(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_vi(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_vi {}", x);
     abort_with_message("Invalid function pointer called with signature 'vi'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_vii(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_vii(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_vii {}", x);
     abort_with_message("Invalid function pointer called with signature 'vii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_viii(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_viii(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_viii {}", x);
     abort_with_message("Invalid function pointer called with signature 'viii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_viiii(x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_viiii(x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_viiii {}", x);
     abort_with_message("Invalid function pointer called with signature 'viiii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_viiiii(_x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_viiiii(_x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_viiiii");
     abort_with_message("Invalid function pointer called with signature 'viiiii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
 
-pub extern "C" fn nullfunc_viiiiii(_x: u32, _instance: &Instance) {
+pub extern "C" fn nullfunc_viiiiii(_x: u32, _vmctx: &mut Ctx) {
     debug!("emscripten::nullfunc_viiiiii");
     abort_with_message("Invalid function pointer called with signature 'viiiiii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
 }
diff --git a/lib/emscripten/src/process.rs b/lib/emscripten/src/process.rs
index 6f65f75e2..ae48bdff8 100644
--- a/lib/emscripten/src/process.rs
+++ b/lib/emscripten/src/process.rs
@@ -1,7 +1,7 @@
 use libc::{abort, c_char, c_int, exit, pid_t, EAGAIN};
 
 use std::ffi::CStr;
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::vm::Ctx;
 
 pub extern "C" fn abort_with_message(message: &str) {
     debug!("emscripten::abort_with_message");
@@ -16,7 +16,7 @@ pub extern "C" fn _abort() {
     }
 }
 
-pub extern "C" fn _fork(_instance: &mut Instance) -> pid_t {
+pub extern "C" fn _fork(_vmctx: &mut Ctx) -> pid_t {
     debug!("emscripten::_fork");
     // unsafe {
     //     fork()
@@ -24,14 +24,14 @@ pub extern "C" fn _fork(_instance: &mut Instance) -> pid_t {
     -1
 }
 
-pub extern "C" fn _exit(status: c_int, _instance: &mut Instance) -> ! {
+pub extern "C" fn _exit(status: c_int, _vmctx: &mut Ctx) -> ! {
     debug!("emscripten::_exit {}", status);
     unsafe { exit(status) }
 }
 
-pub extern "C" fn em_abort(message: u32, instance: &mut Instance) {
+pub extern "C" fn em_abort(message: u32, vmctx: &mut Ctx) {
     debug!("emscripten::em_abort {}", message);
-    let message_addr = instance.memory_offset_addr(0, message as usize) as *mut c_char;
+    let message_addr = vmctx.memory(0)[message as usize] as *mut c_char;
     unsafe {
         let message = CStr::from_ptr(message_addr)
             .to_str()
diff --git a/lib/emscripten/src/signal.rs b/lib/emscripten/src/signal.rs
index 97792588d..1e7c5dbac 100644
--- a/lib/emscripten/src/signal.rs
+++ b/lib/emscripten/src/signal.rs
@@ -1,25 +1,25 @@
 // use super::varargs::VarArgs;
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::vm::Ctx;
 
 #[allow(clippy::cast_ptr_alignment)]
-pub extern "C" fn _sigemptyset(set: u32, instance: &mut Instance) -> i32 {
+pub extern "C" fn _sigemptyset(set: u32, vmctx: &mut Ctx) -> i32 {
     debug!("emscripten::_sigemptyset");
-    let set_addr = instance.memory_offset_addr(0, set as _) as *mut u32;
+    let set_addr = vmctx.memory(0)[set as usize] as *mut u32;
     unsafe {
         *set_addr = 0;
     }
     0
 }
 
-pub extern "C" fn _sigaction(signum: u32, act: u32, oldact: u32, _instance: &mut Instance) -> i32 {
+pub extern "C" fn _sigaction(signum: u32, act: u32, oldact: u32, _vmctx: &mut Ctx) -> i32 {
     debug!("emscripten::_sigaction {}, {}, {}", signum, act, oldact);
     0
 }
 
 #[allow(clippy::cast_ptr_alignment)]
-pub extern "C" fn _sigaddset(set: u32, signum: u32, instance: &mut Instance) -> i32 {
+pub extern "C" fn _sigaddset(set: u32, signum: u32, vmctx: &mut Ctx) -> i32 {
     debug!("emscripten::_sigaddset {}, {}", set, signum);
-    let set_addr = instance.memory_offset_addr(0, set as _) as *mut u32;
+    let set_addr = vmctx.memory(0)[set as usize] as *mut u32;
     unsafe {
         *set_addr |= 1 << (signum - 1);
     }
@@ -31,7 +31,7 @@ pub extern "C" fn _sigprocmask() -> i32 {
     0
 }
 
-pub extern "C" fn _signal(sig: u32, _instance: &mut Instance) -> i32 {
+pub extern "C" fn _signal(sig: u32, _vmctx: &mut Ctx) -> i32 {
     debug!("emscripten::_signal ({})", sig);
     0
 }
diff --git a/lib/emscripten/src/syscalls.rs b/lib/emscripten/src/syscalls.rs
index 7a58c7cb7..3cafdcc64 100644
--- a/lib/emscripten/src/syscalls.rs
+++ b/lib/emscripten/src/syscalls.rs
@@ -70,7 +70,7 @@ use libc::{
     SO_REUSEADDR,
     TIOCGWINSZ,
 };
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::vm::Ctx;
 
 use super::env;
 use std::mem;
@@ -96,9 +96,9 @@ use libc::SO_NOSIGPIPE;
 const SO_NOSIGPIPE: c_int = 0;
 
 /// exit
-pub extern "C" fn ___syscall1(which: c_int, mut varargs: VarArgs, instance: &mut Instance) {
+pub extern "C" fn ___syscall1(which: c_int, mut varargs: VarArgs, vmctx: &mut Ctx) {
     debug!("emscripten::___syscall1 (exit) {}", which);
-    let status: i32 = varargs.get(instance);
+    let status: i32 = varargs.get(vmctx);
     unsafe {
         exit(status);
     }
@@ -108,14 +108,14 @@ pub extern "C" fn ___syscall1(which: c_int, mut varargs: VarArgs, instance: &mut
 pub extern "C" fn ___syscall3(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> ssize_t {
     debug!("emscripten::___syscall3 (read) {}", which);
-    let fd: i32 = varargs.get(instance);
-    let buf: u32 = varargs.get(instance);
-    let count: usize = varargs.get(instance);
+    let fd: i32 = varargs.get(vmctx);
+    let buf: u32 = varargs.get(vmctx);
+    let count: usize = varargs.get(vmctx);
     debug!("=> fd: {}, buf_offset: {}, count: {}", fd, buf, count);
-    let buf_addr = instance.memory_offset_addr(0, buf as usize) as *mut c_void;
+    let buf_addr = vmctx.memory(0)[buf as usize] as *mut c_void;
     let ret = unsafe { read(fd, buf_addr, count) };
     debug!("=> ret: {}", ret);
     ret
@@ -125,14 +125,14 @@ pub extern "C" fn ___syscall3(
 pub extern "C" fn ___syscall4(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall4 (write) {}", which);
-    let fd: i32 = varargs.get(instance);
-    let buf: u32 = varargs.get(instance);
-    let count: u32 = varargs.get(instance);
+    let fd: i32 = varargs.get(vmctx);
+    let buf: u32 = varargs.get(vmctx);
+    let count: u32 = varargs.get(vmctx);
     debug!("=> fd: {}, buf: {}, count: {}", fd, buf, count);
-    let buf_addr = instance.memory_offset_addr(0, buf as usize) as *const c_void;
+    let buf_addr = vmctx.memory(0)[buf as usize] as *const c_void;
     unsafe { write(fd, buf_addr, count as usize) as i32 }
 }
 
@@ -140,13 +140,13 @@ pub extern "C" fn ___syscall4(
 pub extern "C" fn ___syscall5(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall5 (open) {}", which);
-    let pathname: u32 = varargs.get(instance);
-    let flags: i32 = varargs.get(instance);
-    let mode: u32 = varargs.get(instance);
-    let pathname_addr = instance.memory_offset_addr(0, pathname as usize) as *const i8;
+    let pathname: u32 = varargs.get(vmctx);
+    let flags: i32 = varargs.get(vmctx);
+    let mode: u32 = varargs.get(vmctx);
+    let pathname_addr = vmctx.memory(0)[pathname as usize] as *const i8;
     let path_str = unsafe { std::ffi::CStr::from_ptr(pathname_addr).to_str().unwrap() };
     let fd = unsafe { open(pathname_addr, flags, mode) };
     debug!(
@@ -160,10 +160,10 @@ pub extern "C" fn ___syscall5(
 pub extern "C" fn ___syscall6(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall6 (close) {}", which);
-    let fd: i32 = varargs.get(instance);
+    let fd: i32 = varargs.get(vmctx);
     debug!("fd: {}", fd);
     unsafe { close(fd) }
 }
@@ -172,12 +172,12 @@ pub extern "C" fn ___syscall6(
 pub extern "C" fn ___syscall12(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall12 (chdir) {}", which);
-    let path_addr: i32 = varargs.get(instance);
+    let path_addr: i32 = varargs.get(vmctx);
     unsafe {
-        let path_ptr = instance.memory_offset_addr(0, path_addr as usize) as *const i8;
+        let path_ptr = vmctx.memory(0)[path_addr as usize] as *const i8;
         let path = std::ffi::CStr::from_ptr(path_ptr);
         let ret = chdir(path_ptr);
         debug!("=> path: {:?}, ret: {}", path, ret);
@@ -195,12 +195,12 @@ pub extern "C" fn ___syscall20() -> pid_t {
 pub extern "C" fn ___syscall39(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall39 (mkdir) {}", which);
-    let pathname: u32 = varargs.get(instance);
-    let mode: u32 = varargs.get(instance);
-    let pathname_addr = instance.memory_offset_addr(0, pathname as usize) as *const i8;
+    let pathname: u32 = varargs.get(vmctx);
+    let mode: u32 = varargs.get(vmctx);
+    let pathname_addr = vmctx.memory(0)[pathname as usize] as *const i8;
     unsafe { mkdir(pathname_addr, mode as _) }
 }
 
@@ -208,11 +208,11 @@ pub extern "C" fn ___syscall39(
 pub extern "C" fn ___syscall40(
     _which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall40 (rmdir)");
-    let pathname: u32 = varargs.get(instance);
-    let pathname_addr = instance.memory_offset_addr(0, pathname as usize) as *const i8;
+    let pathname: u32 = varargs.get(vmctx);
+    let pathname_addr = vmctx.memory(0)[pathname as usize] as *const i8;
     unsafe { rmdir(pathname_addr) }
 }
 
@@ -220,18 +220,18 @@ pub extern "C" fn ___syscall40(
 pub extern "C" fn ___syscall54(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall54 (ioctl) {}", which);
-    let fd: i32 = varargs.get(instance);
-    let request: u32 = varargs.get(instance);
+    let fd: i32 = varargs.get(vmctx);
+    let request: u32 = varargs.get(vmctx);
     debug!("fd: {}, op: {}", fd, request);
     // Got the equivalents here: https://code.woboq.org/linux/linux/include/uapi/asm-generic/ioctls.h.html
     match request as _ {
         21537 => {
             // FIONBIO
-            let argp: u32 = varargs.get(instance);
-            let argp_ptr = instance.memory_offset_addr(0, argp as _);
+            let argp: u32 = varargs.get(vmctx);
+            let argp_ptr = vmctx.memory(0)[argp as usize] as *mut c_void;
             let ret = unsafe { ioctl(fd, FIONBIO, argp_ptr) };
             debug!("ret(FIONBIO): {}", ret);
             ret
@@ -239,8 +239,8 @@ pub extern "C" fn ___syscall54(
         }
         21523 => {
             // TIOCGWINSZ
-            let argp: u32 = varargs.get(instance);
-            let argp_ptr = instance.memory_offset_addr(0, argp as _);
+            let argp: u32 = varargs.get(vmctx);
+            let argp_ptr = vmctx.memory(0)[argp as usize] as *mut c_void;
             let ret = unsafe { ioctl(fd, TIOCGWINSZ, argp_ptr) };
             debug!("ret(TIOCGWINSZ): {} (harcoded to 0)", ret);
             // ret
@@ -266,11 +266,11 @@ pub extern "C" fn ___syscall54(
 pub extern "C" fn ___syscall57(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall57 (setpgid) {}", which);
-    let pid: i32 = varargs.get(instance);
-    let pgid: i32 = varargs.get(instance);
+    let pid: i32 = varargs.get(vmctx);
+    let pgid: i32 = varargs.get(vmctx);
     unsafe { setpgid(pid, pgid) }
 }
 
@@ -278,12 +278,12 @@ pub extern "C" fn ___syscall57(
 pub extern "C" fn ___syscall63(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall63 (dup2) {}", which);
 
-    let src: i32 = varargs.get(instance);
-    let dst: i32 = varargs.get(instance);
+    let src: i32 = varargs.get(vmctx);
+    let dst: i32 = varargs.get(vmctx);
 
     unsafe { dup2(src, dst) }
 }
@@ -299,11 +299,11 @@ pub extern "C" fn ___syscall64() -> pid_t {
 pub extern "C" fn ___syscall102(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall102 (socketcall) {}", which);
-    let call: u32 = varargs.get(instance);
-    let mut socket_varargs: VarArgs = varargs.get(instance);
+    let call: u32 = varargs.get(vmctx);
+    let mut socket_varargs: VarArgs = varargs.get(vmctx);
 
     #[repr(C)]
     pub struct GuestSockaddrIn {
@@ -330,9 +330,9 @@ pub extern "C" fn ___syscall102(
         1 => {
             debug!("socket: socket");
             // socket (domain: c_int, ty: c_int, protocol: c_int) -> c_int
-            let domain: i32 = socket_varargs.get(instance);
-            let ty: i32 = socket_varargs.get(instance);
-            let protocol: i32 = socket_varargs.get(instance);
+            let domain: i32 = socket_varargs.get(vmctx);
+            let ty: i32 = socket_varargs.get(vmctx);
+            let protocol: i32 = socket_varargs.get(vmctx);
             let fd = unsafe { socket(domain, ty, protocol) };
             // set_cloexec
             unsafe {
@@ -361,10 +361,10 @@ pub extern "C" fn ___syscall102(
             debug!("socket: bind");
             // bind (socket: c_int, address: *const sockaddr, address_len: socklen_t) -> c_int
             // TODO: Emscripten has a different signature.
-            let socket: i32 = socket_varargs.get(instance);
-            let address: u32 = socket_varargs.get(instance);
-            let address_len: u32 = socket_varargs.get(instance);
-            let address = instance.memory_offset_addr(0, address as usize) as *mut sockaddr;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let address: u32 = socket_varargs.get(vmctx);
+            let address_len: u32 = socket_varargs.get(vmctx);
+            let address = vmctx.memory(0)[address as usize] as *mut sockaddr;
 
             // Debug received address
             unsafe {
@@ -388,17 +388,17 @@ pub extern "C" fn ___syscall102(
             debug!("socket: connect");
             // connect (socket: c_int, address: *const sockaddr, len: socklen_t) -> c_int
             // TODO: Emscripten has a different signature.
-            let socket: i32 = socket_varargs.get(instance);
-            let address: u32 = socket_varargs.get(instance);
-            let address_len: u32 = socket_varargs.get(instance);
-            let address = instance.memory_offset_addr(0, address as usize) as *mut sockaddr;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let address: u32 = socket_varargs.get(vmctx);
+            let address_len: u32 = socket_varargs.get(vmctx);
+            let address = vmctx.memory(0)[address as usize] as *mut sockaddr;
             unsafe { connect(socket, address, address_len) }
         }
         4 => {
             debug!("socket: listen");
             // listen (socket: c_int, backlog: c_int) -> c_int
-            let socket: i32 = socket_varargs.get(instance);
-            let backlog: i32 = socket_varargs.get(instance);
+            let socket: i32 = socket_varargs.get(vmctx);
+            let backlog: i32 = socket_varargs.get(vmctx);
             let status = unsafe { listen(socket, backlog) };
             debug!(
                 "=> socketfd: {}, backlog: {} = status: {}",
@@ -409,24 +409,22 @@ pub extern "C" fn ___syscall102(
         5 => {
             debug!("socket: accept");
             // accept (socket: c_int, address: *mut sockaddr, address_len: *mut socklen_t) -> c_int
-            let socket: i32 = socket_varargs.get(instance);
-            let address_addr: u32 = socket_varargs.get(instance);
-            let address_len: u32 = socket_varargs.get(instance);
-            let address = instance.memory_offset_addr(0, address_addr as usize) as *mut sockaddr;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let address_addr: u32 = socket_varargs.get(vmctx);
+            let address_len: u32 = socket_varargs.get(vmctx);
+            let address = vmctx.memory(0)[address_addr as usize] as *mut sockaddr;
 
             debug!(
                 "=> socket: {}, address: {:?}, address_len: {}",
                 socket, address, address_len
             );
-            let address_len_addr =
-                instance.memory_offset_addr(0, address_len as usize) as *mut socklen_t;
+            let address_len_addr = vmctx.memory(0)[address_len as usize] as *mut socklen_t;
             // let mut address_len_addr: socklen_t = 0;
 
             let fd = unsafe { accept(socket, address, address_len_addr) };
 
             unsafe {
-                let address_linux =
-                    instance.memory_offset_addr(0, address_addr as usize) as *mut LinuxSockAddr;
+                let address_linux = vmctx.memory(0)[address_addr as usize] as *mut LinuxSockAddr;
                 (*address_linux).sa_family = (*address).sa_family as u16;
                 (*address_linux).sa_data = (*address).sa_data;
             };
@@ -443,51 +441,48 @@ pub extern "C" fn ___syscall102(
         6 => {
             debug!("socket: getsockname");
             // getsockname (socket: c_int, address: *mut sockaddr, address_len: *mut socklen_t) -> c_int
-            let socket: i32 = socket_varargs.get(instance);
-            let address: u32 = socket_varargs.get(instance);
-            let address_len: u32 = socket_varargs.get(instance);
-            let address = instance.memory_offset_addr(0, address as usize) as *mut sockaddr;
-            let address_len_addr =
-                instance.memory_offset_addr(0, address_len as usize) as *mut socklen_t;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let address: u32 = socket_varargs.get(vmctx);
+            let address_len: u32 = socket_varargs.get(vmctx);
+            let address = vmctx.memory(0)[address as usize] as *mut sockaddr;
+            let address_len_addr = vmctx.memory(0)[address_len as usize] as *mut socklen_t;
             unsafe { getsockname(socket, address, address_len_addr) }
         }
         7 => {
             debug!("socket: getpeername");
             // getpeername (socket: c_int, address: *mut sockaddr, address_len: *mut socklen_t) -> c_int
-            let socket: i32 = socket_varargs.get(instance);
-            let address: u32 = socket_varargs.get(instance);
-            let address_len: u32 = socket_varargs.get(instance);
-            let address = instance.memory_offset_addr(0, address as usize) as *mut sockaddr;
-            let address_len_addr =
-                instance.memory_offset_addr(0, address_len as usize) as *mut socklen_t;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let address: u32 = socket_varargs.get(vmctx);
+            let address_len: u32 = socket_varargs.get(vmctx);
+            let address = vmctx.memory(0)[address as usize] as *mut sockaddr;
+            let address_len_addr = vmctx.memory(0)[address_len as usize] as *mut socklen_t;
             unsafe { getpeername(socket, address, address_len_addr) }
         }
         11 => {
             debug!("socket: sendto");
             // sendto (socket: c_int, buf: *const c_void, len: size_t, flags: c_int, addr: *const sockaddr, addrlen: socklen_t) -> ssize_t
-            let socket: i32 = socket_varargs.get(instance);
-            let buf: u32 = socket_varargs.get(instance);
-            let flags: usize = socket_varargs.get(instance);
-            let len: i32 = socket_varargs.get(instance);
-            let address: u32 = socket_varargs.get(instance);
-            let address_len: u32 = socket_varargs.get(instance);
-            let buf_addr = instance.memory_offset_addr(0, buf as usize) as *mut c_void;
-            let address = instance.memory_offset_addr(0, address as usize) as *mut sockaddr;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let buf: u32 = socket_varargs.get(vmctx);
+            let flags: usize = socket_varargs.get(vmctx);
+            let len: i32 = socket_varargs.get(vmctx);
+            let address: u32 = socket_varargs.get(vmctx);
+            let address_len: u32 = socket_varargs.get(vmctx);
+            let buf_addr = vmctx.memory(0)[buf as usize] as *mut c_void;
+            let address = vmctx.memory(0)[address as usize] as *mut sockaddr;
             unsafe { sendto(socket, buf_addr, flags, len, address, address_len) as i32 }
         }
         12 => {
             debug!("socket: recvfrom");
             // recvfrom (socket: c_int, buf: *const c_void, len: size_t, flags: c_int, addr: *const sockaddr, addrlen: socklen_t) -> ssize_t
-            let socket: i32 = socket_varargs.get(instance);
-            let buf: u32 = socket_varargs.get(instance);
-            let flags: usize = socket_varargs.get(instance);
-            let len: i32 = socket_varargs.get(instance);
-            let address: u32 = socket_varargs.get(instance);
-            let address_len: u32 = socket_varargs.get(instance);
-            let buf_addr = instance.memory_offset_addr(0, buf as usize) as *mut c_void;
-            let address = instance.memory_offset_addr(0, address as usize) as *mut sockaddr;
-            let address_len_addr =
-                instance.memory_offset_addr(0, address_len as usize) as *mut socklen_t;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let buf: u32 = socket_varargs.get(vmctx);
+            let flags: usize = socket_varargs.get(vmctx);
+            let len: i32 = socket_varargs.get(vmctx);
+            let address: u32 = socket_varargs.get(vmctx);
+            let address_len: u32 = socket_varargs.get(vmctx);
+            let buf_addr = vmctx.memory(0)[buf as usize] as *mut c_void;
+            let address = vmctx.memory(0)[address as usize] as *mut sockaddr;
+            let address_len_addr = vmctx.memory(0)[address_len as usize] as *mut socklen_t;
             unsafe { recvfrom(socket, buf_addr, flags, len, address, address_len_addr) as i32 }
         }
         14 => {
@@ -498,16 +493,16 @@ pub extern "C" fn ___syscall102(
             //      https://github.com/openbsd/src/blob/master/sys/sys/socket.h#L156
             // setsockopt (socket: c_int, level: c_int, name: c_int, value: *const c_void, option_len: socklen_t) -> c_int
 
-            let socket: i32 = socket_varargs.get(instance);
+            let socket: i32 = socket_varargs.get(vmctx);
             // SOL_SOCKET = 0xffff (BSD, Linux)
             let level: i32 = SOL_SOCKET;
-            let _: u32 = socket_varargs.get(instance);
+            let _: u32 = socket_varargs.get(vmctx);
             // SO_REUSEADDR = 0x4 (BSD, Linux)
             let name: i32 = SO_REUSEADDR;
-            let _: u32 = socket_varargs.get(instance);
-            let value: u32 = socket_varargs.get(instance);
-            let option_len: u32 = socket_varargs.get(instance);
-            let value_addr = instance.memory_offset_addr(0, value as usize) as *mut c_void; // Endian problem
+            let _: u32 = socket_varargs.get(vmctx);
+            let value: u32 = socket_varargs.get(vmctx);
+            let option_len: u32 = socket_varargs.get(vmctx);
+            let value_addr = vmctx.memory(0)[value as usize] as *mut c_void; // Endian problem
             let ret = unsafe { setsockopt(socket, level, name, value_addr, option_len) };
 
             debug!("=> socketfd: {}, level: {} (SOL_SOCKET/0xffff), name: {} (SO_REUSEADDR/4), value_addr: {:?}, option_len: {} = status: {}", socket, level, name, value_addr, option_len, ret);
@@ -516,32 +511,31 @@ pub extern "C" fn ___syscall102(
         15 => {
             debug!("socket: getsockopt");
             // getsockopt (sockfd: c_int, level: c_int, optname: c_int, optval: *mut c_void, optlen: *mut socklen_t) -> c_int
-            let socket: i32 = socket_varargs.get(instance);
-            let level: i32 = socket_varargs.get(instance);
-            let name: i32 = socket_varargs.get(instance);
-            let value: u32 = socket_varargs.get(instance);
-            let option_len: u32 = socket_varargs.get(instance);
-            let value_addr = instance.memory_offset_addr(0, value as usize) as *mut c_void;
-            let option_len_addr =
-                instance.memory_offset_addr(0, option_len as usize) as *mut socklen_t;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let level: i32 = socket_varargs.get(vmctx);
+            let name: i32 = socket_varargs.get(vmctx);
+            let value: u32 = socket_varargs.get(vmctx);
+            let option_len: u32 = socket_varargs.get(vmctx);
+            let value_addr = vmctx.memory(0)[value as usize] as *mut c_void;
+            let option_len_addr = vmctx.memory(0)[option_len as usize] as *mut socklen_t;
             unsafe { getsockopt(socket, level, name, value_addr, option_len_addr) }
         }
         16 => {
             debug!("socket: sendmsg");
             // sendmsg (fd: c_int, msg: *const msghdr, flags: c_int) -> ssize_t
-            let socket: i32 = socket_varargs.get(instance);
-            let msg: u32 = socket_varargs.get(instance);
-            let flags: i32 = socket_varargs.get(instance);
-            let msg_addr = instance.memory_offset_addr(0, msg as usize) as *const msghdr;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let msg: u32 = socket_varargs.get(vmctx);
+            let flags: i32 = socket_varargs.get(vmctx);
+            let msg_addr = vmctx.memory(0)[msg as usize] as *const msghdr;
             unsafe { sendmsg(socket, msg_addr, flags) as i32 }
         }
         17 => {
             debug!("socket: recvmsg");
             // recvmsg (fd: c_int, msg: *mut msghdr, flags: c_int) -> ssize_t
-            let socket: i32 = socket_varargs.get(instance);
-            let msg: u32 = socket_varargs.get(instance);
-            let flags: i32 = socket_varargs.get(instance);
-            let msg_addr = instance.memory_offset_addr(0, msg as usize) as *mut msghdr;
+            let socket: i32 = socket_varargs.get(vmctx);
+            let msg: u32 = socket_varargs.get(vmctx);
+            let flags: i32 = socket_varargs.get(vmctx);
+            let msg_addr = vmctx.memory(0)[msg as usize] as *mut msghdr;
             unsafe { recvmsg(socket, msg_addr, flags) as i32 }
         }
         _ => {
@@ -556,15 +550,15 @@ pub extern "C" fn ___syscall102(
 pub extern "C" fn ___syscall114(
     _which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> pid_t {
     debug!("emscripten::___syscall114 (wait4)");
-    let pid: pid_t = varargs.get(instance);
-    let status: u32 = varargs.get(instance);
-    let options: c_int = varargs.get(instance);
-    let rusage: u32 = varargs.get(instance);
-    let status_addr = instance.memory_offset_addr(0, status as usize) as *mut c_int;
-    let rusage_addr = instance.memory_offset_addr(0, rusage as usize) as *mut rusage;
+    let pid: pid_t = varargs.get(vmctx);
+    let status: u32 = varargs.get(vmctx);
+    let options: c_int = varargs.get(vmctx);
+    let rusage: u32 = varargs.get(vmctx);
+    let status_addr = vmctx.memory(0)[status as usize] as *mut c_int;
+    let rusage_addr = vmctx.memory(0)[rusage as usize] as *mut rusage;
     let res = unsafe { wait4(pid, status_addr, options, rusage_addr) };
     debug!(
         "=> pid: {}, status: {:?}, options: {}, rusage: {:?} = pid: {}",
@@ -578,12 +572,12 @@ pub extern "C" fn ___syscall114(
 pub extern "C" fn ___syscall122(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall122 (uname) {}", which);
-    let buf: u32 = varargs.get(instance);
+    let buf: u32 = varargs.get(vmctx);
     debug!("=> buf: {}", buf);
-    let buf_addr = instance.memory_offset_addr(0, buf as usize) as *mut utsname;
+    let buf_addr = vmctx.memory(0)[buf as usize] as *mut utsname;
     unsafe { uname(buf_addr) }
 }
 
@@ -592,21 +586,21 @@ pub extern "C" fn ___syscall122(
 pub extern "C" fn ___syscall142(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall142 (newselect) {}", which);
 
-    let nfds: i32 = varargs.get(instance);
-    let readfds: u32 = varargs.get(instance);
-    let writefds: u32 = varargs.get(instance);
-    let exceptfds: u32 = varargs.get(instance);
-    let _timeout: i32 = varargs.get(instance);
+    let nfds: i32 = varargs.get(vmctx);
+    let readfds: u32 = varargs.get(vmctx);
+    let writefds: u32 = varargs.get(vmctx);
+    let exceptfds: u32 = varargs.get(vmctx);
+    let _timeout: i32 = varargs.get(vmctx);
 
     assert!(nfds <= 64, "`nfds` must be less than or equal to 64");
     assert!(exceptfds == 0, "`exceptfds` is not supporrted");
 
-    let readfds_ptr = instance.memory_offset_addr(0, readfds as _) as _;
-    let writefds_ptr = instance.memory_offset_addr(0, writefds as _) as _;
+    let readfds_ptr = vmctx.memory(0)[readfds as usize] as _;
+    let writefds_ptr = vmctx.memory(0)[writefds as usize] as _;
 
     unsafe { select(nfds, readfds_ptr, writefds_ptr, 0 as _, 0 as _) }
 }
@@ -615,26 +609,26 @@ pub extern "C" fn ___syscall142(
 pub extern "C" fn ___syscall192(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall192 (mmap2) {}", which);
-    let addr: i32 = varargs.get(instance);
-    let len: u32 = varargs.get(instance);
-    let prot: i32 = varargs.get(instance);
-    let flags: i32 = varargs.get(instance);
-    let fd: i32 = varargs.get(instance);
-    let off: i32 = varargs.get(instance);
+    let addr: i32 = varargs.get(vmctx);
+    let len: u32 = varargs.get(vmctx);
+    let prot: i32 = varargs.get(vmctx);
+    let flags: i32 = varargs.get(vmctx);
+    let fd: i32 = varargs.get(vmctx);
+    let off: i32 = varargs.get(vmctx);
     debug!(
         "=> addr: {}, len: {}, prot: {}, flags: {}, fd: {}, off: {}",
         addr, len, prot, flags, fd, off
     );
 
     if fd == -1 {
-        let ptr = env::call_memalign(16384, len, instance);
+        let ptr = env::call_memalign(16384, len, vmctx);
         if ptr == 0 {
             return -1;
         }
-        env::call_memset(ptr, 0, len, instance);
+        env::call_memset(ptr, 0, len, vmctx);
         ptr as _
     } else {
         -1
@@ -645,12 +639,12 @@ pub extern "C" fn ___syscall192(
 pub extern "C" fn ___syscall140(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> off_t {
     debug!("emscripten::___syscall140 (lseek) {}", which);
-    let fd: i32 = varargs.get(instance);
-    let offset: i64 = varargs.get(instance);
-    let whence: i32 = varargs.get(instance);
+    let fd: i32 = varargs.get(vmctx);
+    let offset: i64 = varargs.get(vmctx);
+    let whence: i32 = varargs.get(vmctx);
     debug!("=> fd: {}, offset: {}, whence = {}", fd, offset, whence);
     unsafe { lseek(fd, offset, whence) }
 }
@@ -660,19 +654,19 @@ pub extern "C" fn ___syscall140(
 pub extern "C" fn ___syscall145(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> ssize_t {
     debug!("emscripten::___syscall145 (readv) {}", which);
-    // let fd: i32 = varargs.get(instance);
-    // let iov: u32 = varargs.get(instance);
-    // let iovcnt: i32 = varargs.get(instance);
+    // let fd: i32 = varargs.get(vmctx);
+    // let iov: u32 = varargs.get(vmctx);
+    // let iovcnt: i32 = varargs.get(vmctx);
     // debug!("=> fd: {}, iov: {}, iovcnt = {}", fd, iov, iovcnt);
-    // let iov_addr = instance.memory_offset_addr(0, iov as usize) as *mut iovec;
+    // let iov_addr = vmctx.memory(0)[iov as usize] as *mut iovec;
     // unsafe { readv(fd, iov_addr, iovcnt) }
 
-    let fd: i32 = varargs.get(instance);
-    let iov: i32 = varargs.get(instance);
-    let iovcnt: i32 = varargs.get(instance);
+    let fd: i32 = varargs.get(vmctx);
+    let iov: i32 = varargs.get(vmctx);
+    let iovcnt: i32 = varargs.get(vmctx);
 
     #[repr(C)]
     struct GuestIovec {
@@ -684,10 +678,8 @@ pub extern "C" fn ___syscall145(
     let mut ret = 0;
     unsafe {
         for i in 0..iovcnt {
-            let guest_iov_addr =
-                instance.memory_offset_addr(0, (iov + i * 8) as usize) as *mut GuestIovec;
-            let iov_base =
-                instance.memory_offset_addr(0, (*guest_iov_addr).iov_base as usize) as *mut c_void;
+            let guest_iov_addr = vmctx.memory(0)[(iov + i * 8) as usize] as *mut GuestIovec;
+            let iov_base = vmctx.memory(0)[(*guest_iov_addr).iov_base as usize] as *mut c_void;
             let iov_len: usize = (*guest_iov_addr).iov_len as _;
             // debug!("=> iov_addr: {:?}, {:?}", iov_base, iov_len);
             let curr = read(fd, iov_base, iov_len);
@@ -706,12 +698,12 @@ pub extern "C" fn ___syscall145(
 pub extern "C" fn ___syscall146(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> ssize_t {
     debug!("emscripten::___syscall146 (writev) {}", which);
-    let fd: i32 = varargs.get(instance);
-    let iov: i32 = varargs.get(instance);
-    let iovcnt: i32 = varargs.get(instance);
+    let fd: i32 = varargs.get(vmctx);
+    let iov: i32 = varargs.get(vmctx);
+    let iovcnt: i32 = varargs.get(vmctx);
 
     #[repr(C)]
     struct GuestIovec {
@@ -723,10 +715,8 @@ pub extern "C" fn ___syscall146(
     let mut ret = 0;
     unsafe {
         for i in 0..iovcnt {
-            let guest_iov_addr =
-                instance.memory_offset_addr(0, (iov + i * 8) as usize) as *mut GuestIovec;
-            let iov_base = instance.memory_offset_addr(0, (*guest_iov_addr).iov_base as usize)
-                as *const c_void;
+            let guest_iov_addr = vmctx.memory(0)[(iov + i * 8) as usize] as *mut GuestIovec;
+            let iov_base = vmctx.memory(0)[(*guest_iov_addr).iov_base as usize] as *const c_void;
             let iov_len: usize = (*guest_iov_addr).iov_len as _;
             // debug!("=> iov_addr: {:?}, {:?}", iov_base, iov_len);
             let curr = write(fd, iov_base, iov_len);
@@ -744,19 +734,19 @@ pub extern "C" fn ___syscall146(
 pub extern "C" fn ___syscall180(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall180 (pread) {}", which);
-    let fd: i32 = varargs.get(instance);
-    let buf: u32 = varargs.get(instance);
-    let count: u32 = varargs.get(instance);
+    let fd: i32 = varargs.get(vmctx);
+    let buf: u32 = varargs.get(vmctx);
+    let count: u32 = varargs.get(vmctx);
     {
-        let zero: u32 = varargs.get(instance);
+        let zero: u32 = varargs.get(vmctx);
         assert_eq!(zero, 0);
     }
-    let offset: i64 = varargs.get(instance);
+    let offset: i64 = varargs.get(vmctx);
 
-    let buf_ptr = instance.memory_offset_addr(0, buf as _) as _;
+    let buf_ptr = vmctx.memory(0)[buf as usize] as _;
 
     unsafe { pread(fd, buf_ptr, count as _, offset) as _ }
 }
@@ -765,19 +755,19 @@ pub extern "C" fn ___syscall180(
 pub extern "C" fn ___syscall181(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall181 (pwrite) {}", which);
-    let fd: i32 = varargs.get(instance);
-    let buf: u32 = varargs.get(instance);
-    let count: u32 = varargs.get(instance);
+    let fd: i32 = varargs.get(vmctx);
+    let buf: u32 = varargs.get(vmctx);
+    let count: u32 = varargs.get(vmctx);
     {
-        let zero: u32 = varargs.get(instance);
+        let zero: u32 = varargs.get(vmctx);
         assert_eq!(zero, 0);
     }
-    let offset: i64 = varargs.get(instance);
+    let offset: i64 = varargs.get(vmctx);
 
-    let buf_ptr = instance.memory_offset_addr(0, buf as _) as _;
+    let buf_ptr = vmctx.memory(0)[buf as usize] as _;
     let status = unsafe { pwrite(fd, buf_ptr, count as _, offset) as _ };
     debug!(
         "=> fd: {}, buf: {}, count: {}, offset: {} = status:{}",
@@ -790,13 +780,13 @@ pub extern "C" fn ___syscall181(
 pub extern "C" fn ___syscall195(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall195 (stat64) {}", which);
-    let pathname: u32 = varargs.get(instance);
-    let buf: u32 = varargs.get(instance);
+    let pathname: u32 = varargs.get(vmctx);
+    let buf: u32 = varargs.get(vmctx);
 
-    let pathname_addr = instance.memory_offset_addr(0, pathname as usize) as *const i8;
+    let pathname_addr = vmctx.memory(0)[pathname as usize] as *const i8;
 
     unsafe {
         let mut _stat: stat = std::mem::zeroed();
@@ -805,7 +795,7 @@ pub extern "C" fn ___syscall195(
         if ret != 0 {
             return ret;
         }
-        copy_stat_into_wasm(instance, buf, &_stat);
+        copy_stat_into_wasm(vmctx, buf, &_stat);
     }
     0
 }
@@ -814,11 +804,11 @@ pub extern "C" fn ___syscall195(
 pub extern "C" fn ___syscall197(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall197 (fstat64) {}", which);
-    let fd: c_int = varargs.get(instance);
-    let buf: u32 = varargs.get(instance);
+    let fd: c_int = varargs.get(vmctx);
+    let buf: u32 = varargs.get(vmctx);
 
     unsafe {
         let mut stat = std::mem::zeroed();
@@ -827,7 +817,7 @@ pub extern "C" fn ___syscall197(
         if ret != 0 {
             return ret;
         }
-        copy_stat_into_wasm(instance, buf, &stat);
+        copy_stat_into_wasm(vmctx, buf, &stat);
     }
 
     0
@@ -855,15 +845,15 @@ pub extern "C" fn ___syscall202() -> gid_t {
 pub extern "C" fn ___syscall212(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall212 (chown) {}", which);
 
-    let pathname: u32 = varargs.get(instance);
-    let owner: u32 = varargs.get(instance);
-    let group: u32 = varargs.get(instance);
+    let pathname: u32 = varargs.get(vmctx);
+    let owner: u32 = varargs.get(vmctx);
+    let group: u32 = varargs.get(vmctx);
 
-    let pathname_addr = instance.memory_offset_addr(0, pathname as usize) as *const i8;
+    let pathname_addr = vmctx.memory(0)[pathname as usize] as *const i8;
 
     unsafe { chown(pathname_addr, owner, group) }
 }
@@ -872,12 +862,12 @@ pub extern "C" fn ___syscall212(
 pub extern "C" fn ___syscall221(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall221 (fcntl64) {}", which);
     // fcntl64
-    let _fd: i32 = varargs.get(instance);
-    let cmd: u32 = varargs.get(instance);
+    let _fd: i32 = varargs.get(vmctx);
+    let cmd: u32 = varargs.get(vmctx);
     match cmd {
         2 => 0,
         _ => -1,
@@ -888,13 +878,13 @@ pub extern "C" fn ___syscall221(
 pub extern "C" fn ___syscall330(
     _which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> pid_t {
     // Implementation based on description at https://linux.die.net/man/2/dup3
     debug!("emscripten::___syscall330 (dup3)");
-    let oldfd: c_int = varargs.get(instance);
-    let newfd: c_int = varargs.get(instance);
-    let flags: c_int = varargs.get(instance);
+    let oldfd: c_int = varargs.get(vmctx);
+    let newfd: c_int = varargs.get(vmctx);
+    let flags: c_int = varargs.get(vmctx);
 
     if oldfd == newfd {
         return EINVAL;
@@ -926,18 +916,18 @@ pub extern "C" fn ___syscall330(
 pub extern "C" fn ___syscall340(
     which: c_int,
     mut varargs: VarArgs,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___syscall340 (prlimit64), {}", which);
     // NOTE: Doesn't really matter. Wasm modules cannot exceed WASM_PAGE_SIZE anyway.
-    let _pid: i32 = varargs.get(instance);
-    let _resource: i32 = varargs.get(instance);
-    let _new_limit: u32 = varargs.get(instance);
-    let old_limit: u32 = varargs.get(instance);
+    let _pid: i32 = varargs.get(vmctx);
+    let _resource: i32 = varargs.get(vmctx);
+    let _new_limit: u32 = varargs.get(vmctx);
+    let old_limit: u32 = varargs.get(vmctx);
 
     if old_limit != 0 {
         // just report no limits
-        let buf_ptr = instance.memory_offset_addr(0, old_limit as _) as *mut u8;
+        let buf_ptr = vmctx.memory(0)[old_limit as usize] as *mut u8;
         let buf = unsafe { slice::from_raw_parts_mut(buf_ptr, 16) };
 
         LittleEndian::write_i32(&mut buf[..], -1); // RLIM_INFINITY
diff --git a/lib/emscripten/src/time.rs b/lib/emscripten/src/time.rs
index c053f7440..bfaeb8331 100644
--- a/lib/emscripten/src/time.rs
+++ b/lib/emscripten/src/time.rs
@@ -6,7 +6,7 @@ use std::time::SystemTime;
 use time;
 
 use super::env;
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::vm::Ctx;
 
 #[cfg(target_os = "linux")]
 use libc::{CLOCK_MONOTONIC, CLOCK_MONOTONIC_COARSE, CLOCK_REALTIME};
@@ -26,7 +26,7 @@ const CLOCK_MONOTONIC_COARSE: libc::clockid_t = 6;
 
 /// emscripten: _gettimeofday
 #[allow(clippy::cast_ptr_alignment)]
-pub extern "C" fn _gettimeofday(tp: c_int, tz: c_int, instance: &mut Instance) -> c_int {
+pub extern "C" fn _gettimeofday(tp: c_int, tz: c_int, vmctx: &mut Ctx) -> c_int {
     debug!("emscripten::_gettimeofday {} {}", tp, tz);
     #[repr(C)]
     struct GuestTimeVal {
@@ -41,7 +41,7 @@ pub extern "C" fn _gettimeofday(tp: c_int, tz: c_int, instance: &mut Instance) -
     unsafe {
         let now = SystemTime::now();
         let since_epoch = now.duration_since(SystemTime::UNIX_EPOCH).unwrap();
-        let timeval_struct_ptr = instance.memory_offset_addr(0, tp as _) as *mut GuestTimeVal;
+        let timeval_struct_ptr = vmctx.memory(0)[tp as usize] as *mut GuestTimeVal;
 
         (*timeval_struct_ptr).tv_sec = since_epoch.as_secs() as _;
         (*timeval_struct_ptr).tv_usec = since_epoch.subsec_nanos() as _;
@@ -54,7 +54,7 @@ pub extern "C" fn _gettimeofday(tp: c_int, tz: c_int, instance: &mut Instance) -
 pub extern "C" fn _clock_gettime(
     clk_id: libc::clockid_t,
     tp: c_int,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::_clock_gettime {} {}", clk_id, tp);
     #[repr(C)]
@@ -76,7 +76,7 @@ pub extern "C" fn _clock_gettime(
     };
 
     unsafe {
-        let timespec_struct_ptr = instance.memory_offset_addr(0, tp as _) as *mut GuestTimeSpec;
+        let timespec_struct_ptr = vmctx.memory(0)[tp as usize] as *mut GuestTimeSpec;
         (*timespec_struct_ptr).tv_sec = timespec.sec as _;
         (*timespec_struct_ptr).tv_nsec = timespec.nsec as _;
     }
@@ -87,10 +87,10 @@ pub extern "C" fn _clock_gettime(
 pub extern "C" fn ___clock_gettime(
     clk_id: libc::clockid_t,
     tp: c_int,
-    instance: &mut Instance,
+    vmctx: &mut Ctx,
 ) -> c_int {
     debug!("emscripten::___clock_gettime {} {}", clk_id, tp);
-    _clock_gettime(clk_id, tp, instance)
+    _clock_gettime(clk_id, tp, vmctx)
 }
 
 /// emscripten: _clock
@@ -127,8 +127,8 @@ pub extern "C" fn _tvset() {
 
 /// formats time as a C string
 #[allow(clippy::cast_ptr_alignment)]
-unsafe extern "C" fn fmt_time(time: u32, instance: &Instance) -> *const c_char {
-    let date = &*(instance.memory_offset_addr(0, time as _) as *mut guest_tm);
+unsafe extern "C" fn fmt_time(time: u32, vmctx: &mut Ctx) -> *const c_char {
+    let date = &*(vmctx.memory(0)[time as usize] as *mut guest_tm);
 
     let days = vec!["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
     let months = vec![
@@ -152,21 +152,21 @@ unsafe extern "C" fn fmt_time(time: u32, instance: &Instance) -> *const c_char {
 }
 
 /// emscripten: _asctime
-pub extern "C" fn _asctime(time: u32, instance: &mut Instance) -> u32 {
+pub extern "C" fn _asctime(time: u32, vmctx: &mut Ctx) -> u32 {
     debug!("emscripten::_asctime {}", time);
 
     unsafe {
-        let time_str_ptr = fmt_time(time, instance);
-        copy_cstr_into_wasm(instance, time_str_ptr)
+        let time_str_ptr = fmt_time(time, vmctx);
+        copy_cstr_into_wasm(vmctx, time_str_ptr)
 
-        // let c_str = instance.memory_offset_addr(0, res as _) as *mut i8;
+        // let c_str = vmctx.memory(0)[res as usize] as *mut i8;
         // use std::ffi::CStr;
         // debug!("#### cstr = {:?}", CStr::from_ptr(c_str));
     }
 }
 
 /// emscripten: _asctime_r
-pub extern "C" fn _asctime_r(time: u32, buf: u32, instance: &mut Instance) -> u32 {
+pub extern "C" fn _asctime_r(time: u32, buf: u32, vmctx: &mut Ctx) -> u32 {
     debug!("emscripten::_asctime_r {}, {}", time, buf);
 
     unsafe {
@@ -174,10 +174,10 @@ pub extern "C" fn _asctime_r(time: u32, buf: u32, instance: &mut Instance) -> u3
         //      to write out more than 26 bytes (including the null terminator).
         //      See http://pubs.opengroup.org/onlinepubs/9699919799/functions/asctime.html
         //      Our undefined behavior is to truncate the write to at most 26 bytes, including null terminator.
-        let time_str_ptr = fmt_time(time, instance);
-        write_to_buf(time_str_ptr, buf, 26, instance)
+        let time_str_ptr = fmt_time(time, vmctx);
+        write_to_buf(time_str_ptr, buf, 26, vmctx)
 
-        // let c_str = instance.memory_offset_addr(0, res as _) as *mut i8;
+        // let c_str = vmctx.memory(0)[res as usize] as *mut i8;
         // use std::ffi::CStr;
         // debug!("#### cstr = {:?}", CStr::from_ptr(c_str));
     }
@@ -185,21 +185,21 @@ pub extern "C" fn _asctime_r(time: u32, buf: u32, instance: &mut Instance) -> u3
 
 /// emscripten: _localtime
 #[allow(clippy::cast_ptr_alignment)]
-pub extern "C" fn _localtime(time_p: u32, instance: &mut Instance) -> c_int {
+pub extern "C" fn _localtime(time_p: u32, vmctx: &mut Ctx) -> c_int {
     debug!("emscripten::_localtime {}", time_p);
     // NOTE: emscripten seems to want tzset() called in this function
     //      https://stackoverflow.com/questions/19170721/real-time-awareness-of-timezone-change-in-localtime-vs-localtime-r
 
     let timespec = unsafe {
-        let time_p_addr = instance.memory_offset_addr(0, time_p as _) as *mut i64;
+        let time_p_addr = vmctx.memory(0)[time_p as usize] as *mut i64;
         let seconds = *time_p_addr.clone();
         time::Timespec::new(seconds, 0)
     };
     let result_tm = time::at(timespec);
 
     unsafe {
-        let tm_struct_offset = env::call_malloc(mem::size_of::<guest_tm>() as _, instance);
-        let tm_struct_ptr = instance.memory_offset_addr(0, tm_struct_offset as _) as *mut guest_tm;
+        let tm_struct_offset = env::call_malloc(mem::size_of::<guest_tm>() as _, vmctx);
+        let tm_struct_ptr = vmctx.memory(0)[tm_struct_offset as usize] as *mut guest_tm;
         // debug!(
         //     ">>>>>>> time = {}, {}, {}, {}, {}, {}, {}, {}",
         //     result_tm.tm_sec, result_tm.tm_min, result_tm.tm_hour, result_tm.tm_mday,
@@ -222,14 +222,14 @@ pub extern "C" fn _localtime(time_p: u32, instance: &mut Instance) -> c_int {
 }
 /// emscripten: _localtime_r
 #[allow(clippy::cast_ptr_alignment)]
-pub extern "C" fn _localtime_r(time_p: u32, result: u32, instance: &mut Instance) -> c_int {
+pub extern "C" fn _localtime_r(time_p: u32, result: u32, vmctx: &mut Ctx) -> c_int {
     debug!("emscripten::_localtime_r {}", time_p);
 
     // NOTE: emscripten seems to want tzset() called in this function
     //      https://stackoverflow.com/questions/19170721/real-time-awareness-of-timezone-change-in-localtime-vs-localtime-r
 
     unsafe {
-        let seconds = instance.memory_offset_addr(0, time_p as _) as *const i32;
+        let seconds = vmctx.memory(0)[time_p as usize] as *const i32;
         let timespec = time::Timespec::new(*seconds as _, 0);
         let result_tm = time::at(timespec);
 
@@ -239,7 +239,7 @@ pub extern "C" fn _localtime_r(time_p: u32, result: u32, instance: &mut Instance
         //     result_tm.tm_mon, result_tm.tm_year, result_tm.tm_wday, result_tm.tm_yday,
         // );
 
-        let result_addr = instance.memory_offset_addr(0, result as _) as *mut guest_tm;
+        let result_addr = vmctx.memory(0)[result as usize] as *mut guest_tm;
 
         (*result_addr).tm_sec = result_tm.tm_sec;
         (*result_addr).tm_min = result_tm.tm_min;
@@ -259,11 +259,11 @@ pub extern "C" fn _localtime_r(time_p: u32, result: u32, instance: &mut Instance
 
 /// emscripten: _time
 #[allow(clippy::cast_ptr_alignment)]
-pub extern "C" fn _time(time_p: u32, instance: &mut Instance) -> time_t {
+pub extern "C" fn _time(time_p: u32, vmctx: &mut Ctx) -> time_t {
     debug!("emscripten::_time {}", time_p);
 
     unsafe {
-        let time_p_addr = instance.memory_offset_addr(0, time_p as _) as *mut i64;
+        let time_p_addr = vmctx.memory(0)[time_p as usize] as *mut i64;
         libc_time(time_p_addr)
     }
 }
@@ -274,7 +274,7 @@ pub extern "C" fn _strftime(
     maxsize: u32,
     format_ptr: c_int,
     tm_ptr: c_int,
-    _instance: &mut Instance,
+    _vmctx: &mut Ctx,
 ) -> time_t {
     debug!(
         "emscripten::_strftime {} {} {} {}",
diff --git a/lib/emscripten/src/utils.rs b/lib/emscripten/src/utils.rs
index 110802e0f..23bb9e68e 100644
--- a/lib/emscripten/src/utils.rs
+++ b/lib/emscripten/src/utils.rs
@@ -1,4 +1,4 @@
-use wasmer_runtime_core::{module::Module, Instance};
+use wasmer_runtime_core::{module::Module, vm::Ctx};
 //use wasmer_runtime_core::Instance;
 use super::env;
 use libc::stat;
@@ -15,8 +15,8 @@ pub fn is_emscripten_module(module: &Module) -> bool {
     false
 }
 
-pub unsafe fn write_to_buf(string: *const c_char, buf: u32, max: u32, instance: &Instance) -> u32 {
-    let buf_addr = instance.memory_offset_addr(0, buf as _) as *mut c_char;
+pub unsafe fn write_to_buf(string: *const c_char, buf: u32, max: u32, vmctx: &mut Ctx) -> u32 {
+    let buf_addr = vmctx.memory(0)[buf as usize] as *mut c_char;
 
     for i in 0..max {
         *buf_addr.add(i as _) = *string.add(i as _);
@@ -26,11 +26,11 @@ pub unsafe fn write_to_buf(string: *const c_char, buf: u32, max: u32, instance:
 }
 
 /// This function expects nullbyte to be appended.
-pub unsafe fn copy_cstr_into_wasm(instance: &mut Instance, cstr: *const c_char) -> u32 {
+pub unsafe fn copy_cstr_into_wasm(vmctx: &mut Ctx, cstr: *const c_char) -> u32 {
     let s = CStr::from_ptr(cstr).to_str().unwrap();
     let cstr_len = s.len();
-    let space_offset = env::call_malloc((cstr_len as i32) + 1, instance);
-    let raw_memory = instance.memory_offset_addr(0, space_offset as _) as *mut u8;
+    let space_offset = env::call_malloc((cstr_len as i32) + 1, vmctx);
+    let raw_memory = vmctx.memory(0)[space_offset as usize] as *mut u8;
     let slice = slice::from_raw_parts_mut(raw_memory, cstr_len);
 
     for (byte, loc) in s.bytes().zip(slice.iter_mut()) {
@@ -44,23 +44,20 @@ pub unsafe fn copy_cstr_into_wasm(instance: &mut Instance, cstr: *const c_char)
     space_offset
 }
 
-pub unsafe fn allocate_on_stack<'a, T: Copy>(
-    count: u32,
-    instance: &'a Instance,
-) -> (u32, &'a mut [T]) {
+pub unsafe fn allocate_on_stack<'a, T: Copy>(count: u32, vmctx: &'a Ctx) -> (u32, &'a mut [T]) {
     unimplemented!("allocate_on_stack not implemented")
     //    let offset = (instance.emscripten_data().as_ref().unwrap().stack_alloc)(
     //        count * (size_of::<T>() as u32),
-    //        instance,
+    //        vmctx,
     //    );
-    //    let addr = instance.memory_offset_addr(0, offset as _) as *mut T;
+    //    let addr = vmctx.memory(0)[offset as usize] as *mut T;
     //    let slice = slice::from_raw_parts_mut(addr, count as usize);
     //
     //    (offset, slice)
 }
 
-pub unsafe fn allocate_cstr_on_stack<'a>(s: &str, instance: &'a Instance) -> (u32, &'a [u8]) {
-    let (offset, slice) = allocate_on_stack((s.len() + 1) as u32, instance);
+pub unsafe fn allocate_cstr_on_stack<'a>(s: &str, vmctx: &'a Ctx) -> (u32, &'a [u8]) {
+    let (offset, slice) = allocate_on_stack((s.len() + 1) as u32, vmctx);
 
     use std::iter;
     for (byte, loc) in s.bytes().chain(iter::once(0)).zip(slice.iter_mut()) {
@@ -70,10 +67,7 @@ pub unsafe fn allocate_cstr_on_stack<'a>(s: &str, instance: &'a Instance) -> (u3
     (offset, slice)
 }
 
-pub unsafe fn copy_terminated_array_of_cstrs(
-    _instance: &mut Instance,
-    cstrs: *mut *mut c_char,
-) -> u32 {
+pub unsafe fn copy_terminated_array_of_cstrs(_vmctx: &mut Ctx, cstrs: *mut *mut c_char) -> u32 {
     let total_num = {
         let mut ptr = cstrs;
         let mut counter = 0;
@@ -111,8 +105,8 @@ pub struct GuestStat {
 }
 
 #[allow(clippy::cast_ptr_alignment)]
-pub unsafe fn copy_stat_into_wasm(instance: &mut Instance, buf: u32, stat: &stat) {
-    let stat_ptr = instance.memory_offset_addr(0, buf as _) as *mut GuestStat;
+pub unsafe fn copy_stat_into_wasm(vmctx: &mut Ctx, buf: u32, stat: &stat) {
+    let stat_ptr = vmctx.memory(0)[buf as usize] as *mut GuestStat;
     (*stat_ptr).st_dev = stat.st_dev as _;
     (*stat_ptr).__st_dev_padding = 0;
     (*stat_ptr).__st_ino_truncated = stat.st_ino as _;
@@ -144,14 +138,14 @@ mod tests {
     use std::sync::Arc;
     use wabt::wat2wasm;
     use wasmer_clif_backend::CraneliftCompiler;
-    use wasmer_runtime_core::{compile, module::Module};
+    use wasmer_runtime_core::{compile_with, module::Module};
 
     #[test]
     fn should_detect_emscripten_files() {
         const wast_bytes: &[u8] = include_bytes!("tests/is_emscripten_true.wast");
         let wasm_binary = wat2wasm(wast_bytes.to_vec()).expect("Can't convert to wasm");
         let module =
-            compile(&wasm_binary[..], &CraneliftCompiler::new()).expect("WASM can't be compiled");
+            compile_with(&wasm_binary[..], &CraneliftCompiler::new()).expect("WASM can't be compiled");
         let module = Arc::new(module);
         assert!(is_emscripten_module(&module));
     }
@@ -161,7 +155,7 @@ mod tests {
         const wast_bytes: &[u8] = include_bytes!("tests/is_emscripten_false.wast");
         let wasm_binary = wat2wasm(wast_bytes.to_vec()).expect("Can't convert to wasm");
         let module =
-            compile(&wasm_binary[..], &CraneliftCompiler::new()).expect("WASM can't be compiled");
+            compile_with(&wasm_binary[..], &CraneliftCompiler::new()).expect("WASM can't be compiled");
         let module = Arc::new(module);
         assert!(!is_emscripten_module(&module));
     }
diff --git a/lib/emscripten/src/varargs.rs b/lib/emscripten/src/varargs.rs
index 6664ec9a9..dba4f956a 100644
--- a/lib/emscripten/src/varargs.rs
+++ b/lib/emscripten/src/varargs.rs
@@ -1,5 +1,5 @@
 use std::mem;
-use wasmer_runtime_core::Instance;
+use wasmer_runtime_core::vm::Ctx;
 
 #[repr(transparent)]
 pub struct VarArgs {
@@ -7,8 +7,8 @@ pub struct VarArgs {
 }
 
 impl VarArgs {
-    pub fn get<T: Sized>(&mut self, instance: &mut Instance) -> T {
-        let ptr = instance.memory_offset_addr(0, self.pointer as usize);
+    pub fn get<T: Sized>(&mut self, vmctx: &mut Ctx) -> T {
+        let ptr = vmctx.memory(0)[self.pointer as usize];
         self.pointer += mem::size_of::<T>() as u32;
         unsafe { (ptr as *const T).read() }
     }
diff --git a/lib/emscripten/tests/emtests/_common.rs b/lib/emscripten/tests/emtests/_common.rs
index 93f5128cc..5b54bd580 100644
--- a/lib/emscripten/tests/emtests/_common.rs
+++ b/lib/emscripten/tests/emtests/_common.rs
@@ -10,7 +10,7 @@ macro_rules! assert_emscripten_output {
 
         let wasm_bytes = include_bytes!($file);
 
-        let module = wasmer_runtime_core::compile(&wasm_bytes[..], &CraneliftCompiler::new())
+        let module = wasmer_runtime_core::compile_with(&wasm_bytes[..], &CraneliftCompiler::new())
             .expect("WASM can't be compiled");
 
 //        let module = compile(&wasm_bytes[..])
diff --git a/lib/runtime-core/build/spectests.rs b/lib/runtime-core/build/spectests.rs
index 6cbd9ade2..867f99454 100644
--- a/lib/runtime-core/build/spectests.rs
+++ b/lib/runtime-core/build/spectests.rs
@@ -374,7 +374,7 @@ fn test_module_{}() {{
         let start_module_call = format!("start_module_{}", self.last_module);
         self.buffer.push_str(
             format!(
-                "\nfn {}(instance: &mut Instance) {{
+                "\nfn {}(vmctx: &mut Ctx) {{
     // TODO Review is explicit start needed? Start now called in runtime::Instance::new()
     //instance.start();
 }}\n",
@@ -437,7 +437,7 @@ fn {}_assert_invalid() {{
                 let func_name = format!("{}_assert_return_arithmetic_nan", self.command_name());
                 self.buffer.push_str(
                     format!(
-                        "fn {func_name}(instance: &mut Instance) {{
+                        "fn {func_name}(vmctx: &mut Ctx) {{
     println!(\"Executing function {{}}\", \"{func_name}\");
     let result = instance.call(\"{field}\", &[{args_values}]).unwrap().first().expect(\"Missing result in {func_name}\").clone();
     {assertion}
@@ -496,7 +496,7 @@ fn {}_assert_invalid() {{
                 let func_name = format!("{}_assert_return_canonical_nan", self.command_name());
                 self.buffer.push_str(
                     format!(
-                        "fn {func_name}(instance: &mut Instance) {{
+                        "fn {func_name}(vmctx: &mut Ctx) {{
     println!(\"Executing function {{}}\", \"{func_name}\");
     let result = instance.call(\"{field}\", &[{args_values}]).unwrap().first().expect(\"Missing result in {func_name}\").clone();
     {assertion}
@@ -611,7 +611,7 @@ fn {}_assert_malformed() {{
                 let func_name = format!("{}_action_invoke", self.command_name());
                 self.buffer.push_str(
                     format!(
-                        "fn {func_name}(instance: &mut Instance) -> Result<()> {{
+                        "fn {func_name}(vmctx: &mut Ctx) -> Result<()> {{
     println!(\"Executing function {{}}\", \"{func_name}\");
     let result = instance.call(\"{field}\", &[{args_values}]);
     {assertion}