diff --git a/lib/runtime-core/src/backend.rs b/lib/runtime-core/src/backend.rs
index 1d493c314..5f332de91 100644
--- a/lib/runtime-core/src/backend.rs
+++ b/lib/runtime-core/src/backend.rs
@@ -4,6 +4,7 @@ use crate::{
     typed_func::Wasm,
     types::{LocalFuncIndex, SigIndex},
     vm,
+    state::FunctionStateMap,
 };
 
 use crate::{
@@ -84,6 +85,11 @@ pub trait RunnableModule: Send + Sync {
         local_func_index: LocalFuncIndex,
     ) -> Option<NonNull<vm::Func>>;
 
+    fn get_func_statemap(
+        &self,
+        _local_func_index: LocalFuncIndex,
+    ) -> Option<FunctionStateMap> { None }
+
     /// A wasm trampoline contains the necesarry data to dynamically call an exported wasm function.
     /// Given a particular signature index, we are returned a trampoline that is matched with that
     /// signature and an invoke function that can call the trampoline.
diff --git a/lib/runtime-core/src/lib.rs b/lib/runtime-core/src/lib.rs
index d7e56e7df..43b2b9b05 100644
--- a/lib/runtime-core/src/lib.rs
+++ b/lib/runtime-core/src/lib.rs
@@ -43,6 +43,7 @@ pub mod vm;
 pub mod vmcalls;
 #[cfg(all(unix, target_arch = "x86_64"))]
 pub use trampoline_x64 as trampoline;
+pub mod state;
 
 use self::error::CompileResult;
 #[doc(inline)]
diff --git a/lib/runtime-core/src/state.rs b/lib/runtime-core/src/state.rs
new file mode 100644
index 000000000..837e43831
--- /dev/null
+++ b/lib/runtime-core/src/state.rs
@@ -0,0 +1,75 @@
+#[derive(Copy, Clone, Debug)]
+pub struct RegisterIndex(pub usize);
+
+#[derive(Clone, Debug, Default)]
+pub struct FunctionStateMap {
+    pub local_to_locations: Vec<Location>,
+    pub diffs: Vec<StateDiff>,
+}
+
+#[derive(Clone, Debug, Default)]
+pub struct StateDiff {
+    pub last: Option<usize>,
+    pub stack_to_locations_push: Vec<Location>,
+    pub stack_to_locations_pop: usize,
+}
+
+#[derive(Clone, Debug)]
+pub enum Location {
+    Virtual, // no physical storage
+    Memory(RegisterIndex, i32),
+    Register(RegisterIndex),
+}
+
+#[cfg(all(unix, target_arch = "x86_64"))]
+pub mod x64 {
+    use super::*;
+
+    #[repr(u8)]
+    #[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
+    pub enum GPR {
+        RAX,
+        RCX,
+        RDX,
+        RBX,
+        RSP,
+        RBP,
+        RSI,
+        RDI,
+        R8,
+        R9,
+        R10,
+        R11,
+        R12,
+        R13,
+        R14,
+        R15,
+    }
+
+    #[repr(u8)]
+    #[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
+    pub enum XMM {
+        XMM0,
+        XMM1,
+        XMM2,
+        XMM3,
+        XMM4,
+        XMM5,
+        XMM6,
+        XMM7,
+    }
+
+    pub enum X64Register {
+        GPR(GPR),
+        XMM(XMM),
+    }
+
+    impl X64Register {
+        pub fn to_index(&self) -> RegisterIndex {
+            match *self {
+                X64Register::GPR(x) => RegisterIndex(x as usize),
+                X64Register::XMM(x) => RegisterIndex(x as usize + 1000),
+            }
+        }
+    }
+}
diff --git a/lib/singlepass-backend/src/codegen_x64.rs b/lib/singlepass-backend/src/codegen_x64.rs
index 9baa15c22..fa86905de 100644
--- a/lib/singlepass-backend/src/codegen_x64.rs
+++ b/lib/singlepass-backend/src/codegen_x64.rs
@@ -1,4 +1,5 @@
 #![allow(clippy::forget_copy)] // Used by dynasm.
+#![warn(unused_imports)]
 
 use crate::emitter_x64::*;
 use crate::machine::*;
@@ -28,6 +29,7 @@ use wasmer_runtime_core::{
         TableIndex, Type,
     },
     vm::{self, LocalGlobal, LocalTable, INTERNALS_SIZE},
+    state::{FunctionStateMap, StateDiff, x64::X64Register, Location as StateLocation},
 };
 use wasmparser::{Operator, Type as WpType};
 
@@ -139,6 +141,7 @@ enum LocalOrTemp {
 pub struct X64FunctionCode {
     signatures: Arc<Map<SigIndex, FuncSig>>,
     function_signatures: Arc<Map<FuncIndex, SigIndex>>,
+    state_map: FunctionStateMap,
 
     assembler: Option<Assembler>,
     function_labels: Option<HashMap<usize, (DynamicLabel, Option<AssemblyOffset>)>>,
@@ -356,6 +359,7 @@ impl ModuleCodeGenerator<X64FunctionCode, X64ExecutionContext, CodegenError>
         let code = X64FunctionCode {
             signatures: self.signatures.as_ref().unwrap().clone(),
             function_signatures: self.function_signatures.as_ref().unwrap().clone(),
+            state_map: FunctionStateMap::default(),
 
             assembler: Some(assembler),
             function_labels: Some(function_labels),
diff --git a/lib/singlepass-backend/src/emitter_x64.rs b/lib/singlepass-backend/src/emitter_x64.rs
index f94de7013..ea8018a29 100644
--- a/lib/singlepass-backend/src/emitter_x64.rs
+++ b/lib/singlepass-backend/src/emitter_x64.rs
@@ -1,38 +1,5 @@
 use dynasmrt::{x64::Assembler, AssemblyOffset, DynamicLabel, DynasmApi, DynasmLabelApi};
-
-#[repr(u8)]
-#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
-pub enum GPR {
-    RAX,
-    RCX,
-    RDX,
-    RBX,
-    RSP,
-    RBP,
-    RSI,
-    RDI,
-    R8,
-    R9,
-    R10,
-    R11,
-    R12,
-    R13,
-    R14,
-    R15,
-}
-
-#[repr(u8)]
-#[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
-pub enum XMM {
-    XMM0,
-    XMM1,
-    XMM2,
-    XMM3,
-    XMM4,
-    XMM5,
-    XMM6,
-    XMM7,
-}
+pub use wasmer_runtime_core::state::x64::{GPR, XMM};
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub enum Location {