diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index 8dfe593..059df29 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -1,11 +1,13 @@
 //! Backend: IR to Wasm.
 
+use crate::cfg::CFGInfo;
 use crate::entity::{EntityRef, PerEntity};
 use crate::ir::{Block, FunctionBody, Value, ValueDef};
 use crate::passes::rpo::{RPOIndex, RPO};
 use anyhow::Result;
 
 pub mod stackify;
+use stackify::{Context as StackifyContext, WasmBlock};
 pub mod treeify;
 use treeify::Trees;
 
@@ -13,13 +15,24 @@ pub struct WasmBackend<'a> {
     body: &'a FunctionBody,
     rpo: RPO,
     trees: Trees,
+    ctrl: Vec<WasmBlock<'a>>,
 }
 
 impl<'a> WasmBackend<'a> {
     pub fn new(body: &'a FunctionBody) -> Result<WasmBackend<'a>> {
+        let cfg = CFGInfo::new(body);
         let rpo = RPO::compute(body);
+        log::trace!("RPO:\n{:?}\n", rpo);
         let trees = Trees::compute(body);
-        Ok(WasmBackend { body, rpo, trees })
+        log::trace!("Trees:\n{:?}\n", trees);
+        let ctrl = StackifyContext::new(body, &cfg, &rpo).compute();
+        log::trace!("Ctrl:\n{:?}\n", ctrl);
+        Ok(WasmBackend {
+            body,
+            rpo,
+            trees,
+            ctrl,
+        })
     }
 
     pub fn compile(&self) -> Result<Vec<u8>> {
diff --git a/src/backend/stackify.rs b/src/backend/stackify.rs
index e04c6e6..067b0f6 100644
--- a/src/backend/stackify.rs
+++ b/src/backend/stackify.rs
@@ -69,10 +69,10 @@ impl WasmLabel {
     }
 }
 
-struct Context<'a> {
+pub struct Context<'a, 'b> {
     body: &'a FunctionBody,
-    cfg: &'a CFGInfo,
-    rpo: &'a RPO,
+    cfg: &'b CFGInfo,
+    rpo: &'b RPO,
     merge_nodes: HashSet<Block>,
     loop_headers: HashSet<Block>,
     ctrl_stack: Vec<CtrlEntry>,
@@ -95,8 +95,8 @@ impl CtrlEntry {
     }
 }
 
-impl<'a> Context<'a> {
-    fn new(body: &'a FunctionBody, cfg: &'a CFGInfo, rpo: &'a RPO) -> Self {
+impl<'a, 'b> Context<'a, 'b> {
+    pub fn new(body: &'a FunctionBody, cfg: &'b CFGInfo, rpo: &'b RPO) -> Self {
         let (merge_nodes, loop_headers) =
             Self::compute_merge_nodes_and_loop_headers(body, cfg, rpo);
         Self {
@@ -109,6 +109,12 @@ impl<'a> Context<'a> {
         }
     }
 
+    pub fn compute(mut self) -> Vec<WasmBlock<'a>> {
+        let mut body = vec![];
+        self.handle_dom_subtree(self.cfg.entry, &mut body);
+        body
+    }
+
     fn compute_merge_nodes_and_loop_headers(
         body: &FunctionBody,
         cfg: &CFGInfo,
diff --git a/src/backend/treeify.rs b/src/backend/treeify.rs
index 30206eb..30b03f6 100644
--- a/src/backend/treeify.rs
+++ b/src/backend/treeify.rs
@@ -10,6 +10,7 @@ use std::convert::TryFrom;
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct ValueArg(Value, u16);
 
+#[derive(Clone, Debug)]
 pub struct Trees {
     /// Is a value placed "under" the given arg slot of the given
     /// other value?