diff --git a/Cargo.lock b/Cargo.lock
index 0c63def..6e6f5d3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -574,6 +574,7 @@ name = "uwucc"
 version = "0.1.0"
 dependencies = [
  "analysis",
+ "bumpalo",
  "dbg-pls",
  "parser",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 248537a..406ada9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,6 +9,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+bumpalo = "3.10.0"
 analysis = { path = "./analysis" }
 parser = { path = "./parser" }
 dbg-pls = { version = "0.3.2", features = ["derive", "colors"] }
diff --git a/analysis/src/ir.rs b/analysis/src/ir.rs
index 7d852d4..df8cafb 100644
--- a/analysis/src/ir.rs
+++ b/analysis/src/ir.rs
@@ -33,6 +33,8 @@
 
 mod pretty;
 
+use std::fmt::{Debug, Display};
+
 use parser::{Span, Symbol};
 pub use pretty::{func_to_string, ir_to_string};
 use rustc_hash::FxHashMap;
@@ -43,30 +45,33 @@ use crate::ty::Ty;
 pub struct DefId(u32);
 
 #[derive(Debug, Clone)]
-pub struct TyLayout {
-    pub ty: Ty,
-    pub layout: Layout,
+pub struct TyLayout<'cx> {
+    pub ty: Ty<'cx>,
+    pub layout: &'cx Layout,
 }
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Layout {
     pub size: u64,
     pub align: u64,
 }
 
-pub struct Ir {
-    pub funcs: FxHashMap<DefId, Func>,
+pub struct Ir<'cx> {
+    pub funcs: FxHashMap<DefId, Func<'cx>>,
 }
 
 #[derive(Debug, Clone)]
-pub struct Func {
-    pub regs: Vec<RegisterData>,
+pub struct Func<'cx> {
+    pub regs: Vec<RegisterData<'cx>>,
     pub bbs: Vec<BasicBlock>,
     pub name: Symbol,
     pub def_span: Span,
-    pub ret_ty: Ty,
+    pub ret_ty: Ty<'cx>,
 }
 
+#[derive(Clone, Copy)]
+pub struct BbIdx(pub u32);
+
 #[derive(Debug, Clone)]
 pub struct BasicBlock {
     pub statements: Vec<Statement>,
@@ -74,8 +79,8 @@ pub struct BasicBlock {
 }
 
 #[derive(Debug, Clone)]
-pub struct RegisterData {
-    pub tyl: TyLayout,
+pub struct RegisterData<'cx> {
+    pub tyl: TyLayout<'cx>,
     pub name: Option<Symbol>,
 }
 
@@ -133,8 +138,12 @@ pub enum Operand {
 
 #[derive(Debug, Clone)]
 pub enum Branch {
-    Goto(u32),
-    Switch { cond: Operand, yes: u32, no: u32 },
+    Goto(BbIdx),
+    Switch {
+        cond: Operand,
+        yes: BbIdx,
+        no: BbIdx,
+    },
     Ret(Operand),
 }
 
@@ -159,6 +168,33 @@ pub enum ConstValue {
     Int(u128),
 }
 
+impl Func<'_> {
+    pub fn bb_mut(&mut self, i: BbIdx) -> &mut BasicBlock {
+        &mut self.bbs[i.as_usize()]
+    }
+}
+
+impl BbIdx {
+    pub fn from_usize(n: usize) -> Self {
+        Self(n.try_into().unwrap())
+    }
+    pub fn as_usize(self) -> usize {
+        self.0 as _
+    }
+}
+
+impl Debug for BbIdx {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "bb{}", self.0)
+    }
+}
+
+impl Display for BbIdx {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "bb{}", self.0)
+    }
+}
+
 impl Layout {
     pub fn size_align(size: u64, align: u64) -> Self {
         Self { size, align }
diff --git a/analysis/src/ir/pretty.rs b/analysis/src/ir/pretty.rs
index ba8965d..e4f2700 100644
--- a/analysis/src/ir/pretty.rs
+++ b/analysis/src/ir/pretty.rs
@@ -1,15 +1,15 @@
 use std::fmt::{Display, Formatter, Result, Write};
 
-use super::{BinKind, Branch, ConstValue, Func, Ir, Operand, StatementKind};
+use super::{BinKind, Branch, ConstValue, Func, Ir, Operand, StatementKind, BbIdx};
 use crate::ir::Register;
 
-pub fn ir_to_string(ir: &Ir) -> String {
+pub fn ir_to_string(ir: &Ir<'_>) -> String {
     let mut buf = String::new();
     PrettyPrinter { out: &mut buf }.ir(ir).unwrap();
     buf
 }
 
-pub fn func_to_string(func: &Func) -> String {
+pub fn func_to_string(func: &Func<'_>) -> String {
     let mut buf = String::new();
     PrettyPrinter { out: &mut buf }.func(func).unwrap();
     buf
@@ -20,14 +20,14 @@ pub struct PrettyPrinter<W> {
 }
 
 impl<W: Write> PrettyPrinter<W> {
-    pub fn ir(&mut self, ir: &Ir) -> Result {
+    pub fn ir(&mut self, ir: &Ir<'_>) -> Result {
         for (_, func) in &ir.funcs {
             self.func(func)?;
         }
         Ok(())
     }
 
-    pub fn func(&mut self, func: &Func) -> Result {
+    pub fn func(&mut self, func: &Func<'_>) -> Result {
         writeln!(self.out, "def {}() {{", func.name)?;
 
         let print_reg = |reg: Register| {
@@ -48,7 +48,7 @@ impl<W: Write> PrettyPrinter<W> {
             if i > 0 {
                 writeln!(self.out)?;
             }
-            writeln!(self.out, "  {i}:")?;
+            writeln!(self.out, "  {}:", BbIdx::from_usize(i))?;
 
             for stmt in &bb.statements {
                 match stmt.kind {
@@ -144,9 +144,11 @@ impl<W: Write> PrettyPrinter<W> {
 
             match bb.term {
                 Branch::Goto(bbn) => writeln!(self.out, "    goto {}", bbn)?,
-                Branch::Switch { cond, yes, no } => {
-                    writeln!(self.out, "    switch {}, {yes}, {no}", print_op(cond))?
-                }
+                Branch::Switch { cond, yes, no } => writeln!(
+                    self.out,
+                    "    switch {}, then {yes}, else {no}",
+                    print_op(cond)
+                )?,
                 Branch::Ret(op) => writeln!(self.out, "    ret {}", print_op(op))?,
             }
         }
diff --git a/analysis/src/lower.rs b/analysis/src/lower.rs
index a1136ae..78f0e10 100644
--- a/analysis/src/lower.rs
+++ b/analysis/src/lower.rs
@@ -1,24 +1,104 @@
 mod builder;
 
+use std::cell::RefCell;
+
 use parser::{
     ast::{self, Atom, DeclAttr, Expr, ExternalDecl, Stmt, TranslationUnit, TypeSpecifier},
     Span, Symbol,
 };
-use rustc_hash::FxHashMap;
+use rustc_hash::{FxHashMap, FxHashSet};
 
 use self::builder::FuncBuilder;
 use crate::{
-    ir::{BinKind, ConstValue, Func, Ir, Layout, Operand, Register, TyLayout},
-    ty::Ty,
+    ir::{BinKind, Branch, ConstValue, Func, Ir, Layout, Operand, Register, TyLayout},
+    ty::{Ty, TyKind},
     Error,
 };
 
 type Result<T, E = Error> = std::result::Result<T, E>;
 
-struct LoweringCx {}
+#[derive(Debug)]
+struct LoweringCx<'cx> {
+    tys: RefCell<FxHashSet<&'cx TyKind<'cx>>>,
+    layouts: RefCell<FxHashSet<&'cx Layout>>,
+    arena: &'cx bumpalo::Bump,
+}
 
-pub fn lower_translation_unit(ast: &TranslationUnit) -> Result<Ir, Error> {
-    let mut lcx = LoweringCx {};
+impl<'cx> LoweringCx<'cx> {
+    fn lower_ty(&self, ty: &TypeSpecifier) -> Ty<'cx> {
+        let kind = match ty {
+            TypeSpecifier::Void => TyKind::Void,
+            TypeSpecifier::Char => TyKind::Char,
+            TypeSpecifier::SChar => TyKind::SChar,
+            TypeSpecifier::UChar => TyKind::UChar,
+            TypeSpecifier::Integer(int) => TyKind::Integer(*int),
+            TypeSpecifier::Float => TyKind::Float,
+            TypeSpecifier::Double => TyKind::Double,
+            TypeSpecifier::LongDouble => TyKind::LongDouble,
+            TypeSpecifier::Bool => TyKind::Bool,
+        };
+        self.intern_ty(kind)
+    }
+
+    fn intern_ty(&self, kind: TyKind<'cx>) -> Ty<'cx> {
+        let opt_kind = self.tys.borrow().get(&kind).copied();
+        match opt_kind {
+            Some(ty) => Ty::new_unchecked(ty),
+            None => {
+                let kind = self.arena.alloc(kind);
+                self.tys.borrow_mut().insert(kind);
+                Ty::new_unchecked(kind)
+            }
+        }
+    }
+
+    fn intern_layout(&self, layout: Layout) -> &'cx Layout {
+        let opt_layout = self.layouts.borrow().get(&layout).copied();
+        match opt_layout {
+            Some(layout) => layout,
+            None => {
+                let layout = self.arena.alloc(layout);
+                self.layouts.borrow_mut().insert(layout);
+                layout
+            }
+        }
+    }
+
+    fn layout_of(&self, ty: Ty<'cx>) -> TyLayout<'cx> {
+        let layout = match *ty {
+            TyKind::Void => Layout::size_align(0, 1),
+            TyKind::Char => Layout::size_align(1, 1),
+            TyKind::SChar => Layout::size_align(1, 1),
+            TyKind::UChar => Layout::size_align(1, 1),
+            TyKind::Integer(int) => match int.kind {
+                parser::ast::IntTyKind::Short => Layout::size_align(2, 2),
+                parser::ast::IntTyKind::Int => Layout::size_align(4, 4),
+                parser::ast::IntTyKind::Long => Layout::size_align(8, 8),
+                parser::ast::IntTyKind::LongLong => Layout::size_align(8, 8),
+            },
+            TyKind::Float => Layout::size_align(4, 4),
+            TyKind::Double => Layout::size_align(8, 8),
+            TyKind::LongDouble => Layout::size_align(8, 8),
+            TyKind::Bool => Layout::size_align(1, 1),
+            TyKind::Struct(_) => todo!("layout_of struct"),
+            TyKind::Union(_) => todo!("layout_of union"),
+            TyKind::Enum(_) => todo!("layout_of enum"),
+            TyKind::Ptr(_) => Layout::size_align(8, 8),
+        };
+        let layout = self.intern_layout(layout);
+        TyLayout { ty, layout }
+    }
+}
+
+pub fn lower_translation_unit<'cx>(
+    arena: &'cx bumpalo::Bump,
+    ast: &TranslationUnit,
+) -> Result<Ir<'cx>, Error> {
+    let mut lcx = LoweringCx {
+        tys: RefCell::default(),
+        layouts: RefCell::default(),
+        arena,
+    };
 
     for (decl, _) in ast {
         match decl {
@@ -26,7 +106,7 @@ pub fn lower_translation_unit(ast: &TranslationUnit) -> Result<Ir, Error> {
             ExternalDecl::FunctionDef(def) => {
                 let decl = def.decl.uwnrap_normal();
                 let body = &def.body;
-                let ret_ty = lower_ty(&decl.decl_spec.ty);
+                let ret_ty = lcx.lower_ty(&decl.decl_spec.ty);
                 lower_body(
                     &mut lcx,
                     body,
@@ -38,17 +118,18 @@ pub fn lower_translation_unit(ast: &TranslationUnit) -> Result<Ir, Error> {
         }
     }
 
-    todo!()
+    todo!("building is not really")
 }
 
 #[derive(Debug)]
-struct FnLoweringCtxt {
-    scopes: Vec<FxHashMap<Symbol, VariableInfo>>,
-    build: FuncBuilder,
+struct FnLoweringCtxt<'a, 'cx> {
+    scopes: Vec<FxHashMap<Symbol, VariableInfo<'cx>>>,
+    build: FuncBuilder<'a, 'cx>,
+    lcx: &'a LoweringCx<'cx>,
 }
 
-impl FnLoweringCtxt {
-    fn resolve_ident(&self, ident: Symbol) -> Option<&VariableInfo> {
+impl<'a, 'cx> FnLoweringCtxt<'a, 'cx> {
+    fn resolve_ident(&self, ident: Symbol) -> Option<&VariableInfo<'cx>> {
         self.scopes.iter().rev().find_map(|s| s.get(&ident))
     }
 
@@ -63,11 +144,11 @@ impl FnLoweringCtxt {
         match stmt {
             Stmt::Decl(decl) => {
                 let decl = decl.uwnrap_normal();
-                let ty = lower_ty(&decl.decl_spec.ty);
+                let ty = self.lcx.lower_ty(&decl.decl_spec.ty);
                 let decl_attr = decl.decl_spec.attrs;
 
                 for (var, def_span) in &decl.init_declarators {
-                    let tyl = layout_of(ty.clone());
+                    let tyl = self.lcx.layout_of(ty.clone());
                     let (name, _) = var.declarator.decl.name();
                     let ptr_to = self.build.alloca(&tyl.layout, Some(name), stmt_span);
 
@@ -75,18 +156,50 @@ impl FnLoweringCtxt {
                         def_span: *def_span,
                         ptr_to,
                         decl_attr,
-                        tyl,
+                        tyl: tyl.clone(),
                     };
                     self.scopes.last_mut().unwrap().insert(name, variable_info);
+                    if let Some((init, init_span)) = &var.init {
+                        let init = self.lower_expr(init, *init_span)?;
+                        self.build.store(ptr_to, init, tyl.layout, *init_span);
+                    }
                 }
             }
             Stmt::Labeled { .. } => todo!("labels are not implemented"),
             Stmt::Compound(_) => todo!("blocks are not implemented"),
             Stmt::If {
                 cond,
-                then,
+                then: then_body,
                 otherwise,
-            } => todo!(),
+            } => {
+                let cond = self.lower_expr(&cond.0, cond.1)?;
+                let pred = self.build.current_bb;
+                let then = self.build.new_block();
+                let els = otherwise
+                    .as_deref()
+                    .map(|oth| (oth, self.build.new_block()));
+                let cont = self.build.new_block();
+
+                self.build.current_bb = then;
+                self.lower_body(&then_body)?;
+                self.build.cur_bb_mut().term = Branch::Goto(cont);
+
+                let false_branch = match els {
+                    Some((otherwise, els)) => {
+                        self.build.current_bb = els;
+                        self.lower_body(&otherwise)?;
+                        self.build.cur_bb_mut().term = Branch::Goto(cont);
+                        els
+                    }
+                    None => cont,
+                };
+                self.build.bb_mut(pred).term = Branch::Switch {
+                    cond,
+                    yes: then,
+                    no: false_branch,
+                };
+                self.build.current_bb = cont;
+            }
             Stmt::Switch => todo!(),
             Stmt::While { cond, body } => todo!(),
             Stmt::For {
@@ -160,7 +273,13 @@ impl FnLoweringCtxt {
                     ast::BinaryOp::Assign(_) => todo!("no assign"),
                 };
 
-                let reg = self.build.binary(kind, lhs, rhs, span, layout_of(Ty::Void));
+                let reg = self.build.binary(
+                    kind,
+                    lhs,
+                    rhs,
+                    span,
+                    self.lcx.layout_of(self.lcx.intern_ty(TyKind::Void)),
+                );
 
                 Ok(Operand::Reg(reg))
             }
@@ -173,7 +292,12 @@ impl FnLoweringCtxt {
                             .map(|(arg, sp)| self.lower_expr(arg, *sp))
                             .collect::<Result<_, _>>()?;
 
-                        let reg = self.build.call(layout_of(Ty::Void), lhs, args, span);
+                        let reg = self.build.call(
+                            self.lcx.layout_of(self.lcx.intern_ty(TyKind::Void)),
+                            lhs,
+                            args,
+                            span,
+                        );
                         Ok(Operand::Reg(reg))
                     }
                     ast::PostfixOp::Member(_) => todo!("member expr"),
@@ -189,65 +313,28 @@ impl FnLoweringCtxt {
 }
 
 #[derive(Debug)]
-struct VariableInfo {
+struct VariableInfo<'cx> {
     def_span: Span,
-    tyl: TyLayout,
+    tyl: TyLayout<'cx>,
     ptr_to: Register,
     decl_attr: DeclAttr,
 }
 
-fn lower_body(
+fn lower_body<'cx>(
     // may be used later
-    _lcx: &mut LoweringCx,
+    lcx: &LoweringCx<'cx>,
     body: &[(Stmt, Span)],
     def_span: Span,
     name: Symbol,
-    ret_ty: Ty,
-) -> Result<Func, Error> {
-    let mut cx: FnLoweringCtxt = FnLoweringCtxt {
+    ret_ty: Ty<'cx>,
+) -> Result<Func<'cx>, Error> {
+    let mut cx = FnLoweringCtxt {
         scopes: vec![FxHashMap::default()],
-        build: FuncBuilder::new(name, def_span, ret_ty),
+        build: FuncBuilder::new(name, def_span, ret_ty, lcx),
+        lcx,
     };
 
     cx.lower_body(body)?;
 
     Ok(cx.build.finish())
 }
-
-fn lower_ty(ty: &TypeSpecifier) -> Ty {
-    match ty {
-        TypeSpecifier::Void => Ty::Void,
-        TypeSpecifier::Char => Ty::Char,
-        TypeSpecifier::SChar => Ty::SChar,
-        TypeSpecifier::UChar => Ty::UChar,
-        TypeSpecifier::Integer(int) => Ty::Integer(*int),
-        TypeSpecifier::Float => Ty::Float,
-        TypeSpecifier::Double => Ty::Double,
-        TypeSpecifier::LongDouble => Ty::LongDouble,
-        TypeSpecifier::Bool => Ty::Bool,
-    }
-}
-
-fn layout_of(ty: Ty) -> TyLayout {
-    let layout = match ty {
-        Ty::Void => Layout::size_align(0, 1),
-        Ty::Char => Layout::size_align(1, 1),
-        Ty::SChar => Layout::size_align(1, 1),
-        Ty::UChar => Layout::size_align(1, 1),
-        Ty::Integer(int) => match int.kind {
-            parser::ast::IntTyKind::Short => Layout::size_align(2, 2),
-            parser::ast::IntTyKind::Int => Layout::size_align(4, 4),
-            parser::ast::IntTyKind::Long => Layout::size_align(8, 8),
-            parser::ast::IntTyKind::LongLong => Layout::size_align(8, 8),
-        },
-        Ty::Float => Layout::size_align(4, 4),
-        Ty::Double => Layout::size_align(8, 8),
-        Ty::LongDouble => Layout::size_align(8, 8),
-        Ty::Bool => Layout::size_align(1, 1),
-        Ty::Struct(_) => todo!("layout_of struct"),
-        Ty::Union(_) => todo!("layout_of union"),
-        Ty::Enum(_) => todo!("layout_of enum"),
-        Ty::Ptr(_) => Layout::size_align(8, 8),
-    };
-    TyLayout { ty, layout }
-}
diff --git a/analysis/src/lower/builder.rs b/analysis/src/lower/builder.rs
index 7d213c5..28e4565 100644
--- a/analysis/src/lower/builder.rs
+++ b/analysis/src/lower/builder.rs
@@ -1,45 +1,50 @@
 use parser::{Span, Symbol};
 
-use super::layout_of;
+use super::LoweringCx;
 use crate::{
     ir::{
-        self, BasicBlock, BinKind, Branch, ConstValue, Func, Layout, Operand, Register,
+        self, BasicBlock, BbIdx, BinKind, Branch, ConstValue, Func, Layout, Operand, Register,
         RegisterData, Statement, StatementKind, TyLayout,
     },
-    ty::Ty,
+    ty::{Ty, TyKind},
 };
 
 #[derive(Debug)]
-pub struct FuncBuilder {
-    pub ir: Func,
-    current_bb: u32,
+pub(super) struct FuncBuilder<'a, 'cx> {
+    pub lcx: &'a LoweringCx<'cx>,
+    pub ir: Func<'cx>,
+    pub current_bb: BbIdx,
 }
 
-impl FuncBuilder {
-    pub fn new(name: Symbol, def_span: Span, ret_ty: Ty) -> Self {
+impl<'a, 'cx> FuncBuilder<'a, 'cx> {
+    pub fn new(name: Symbol, def_span: Span, ret_ty: Ty<'cx>, lcx: &'a LoweringCx<'cx>) -> Self {
         Self {
             ir: Func {
                 regs: Vec::new(),
                 bbs: vec![BasicBlock {
                     statements: Vec::new(),
-                    term: Branch::Goto(0),
+                    term: Branch::Goto(BbIdx(0)),
                 }],
                 name,
                 def_span,
                 ret_ty,
             },
-            current_bb: 0,
+            current_bb: BbIdx(0),
+            lcx,
         }
     }
 
-    pub fn new_reg(&mut self, name: Option<Symbol>, tyl: TyLayout) -> Register {
+    pub fn new_reg(&mut self, name: Option<Symbol>, tyl: TyLayout<'cx>) -> Register {
         let reg = Register(self.ir.regs.len().try_into().unwrap());
         self.ir.regs.push(RegisterData { name, tyl });
         reg
     }
 
     pub fn alloca(&mut self, layout: &Layout, name: Option<Symbol>, span: Span) -> Register {
-        let reg = self.new_reg(name, layout_of(Ty::Ptr(Box::new(Ty::Void))));
+        let void_ptr = self
+            .lcx
+            .intern_ty(TyKind::Ptr(self.lcx.intern_ty(TyKind::Void)));
+        let reg = self.new_reg(name, self.lcx.layout_of(void_ptr));
         let stmt = Statement {
             span,
             kind: StatementKind::Alloca {
@@ -48,7 +53,7 @@ impl FuncBuilder {
                 align: Operand::Const(ConstValue::u64(layout.align)),
             },
         };
-        self.bb_mut().statements.push(stmt);
+        self.cur_bb_mut().statements.push(stmt);
         reg
     }
 
@@ -58,7 +63,7 @@ impl FuncBuilder {
         lhs: Operand,
         rhs: Operand,
         span: Span,
-        result_tyl: TyLayout,
+        result_tyl: TyLayout<'cx>,
     ) -> Register {
         let reg = self.new_reg(None, result_tyl);
         let stmt = StatementKind::BinOp {
@@ -67,13 +72,13 @@ impl FuncBuilder {
             rhs,
             result: reg,
         };
-        self.bb_mut()
+        self.cur_bb_mut()
             .statements
             .push(Statement { span, kind: stmt });
         reg
     }
 
-    pub fn load(&mut self, tyl: TyLayout, ptr_reg: Register, span: Span) -> Register {
+    pub fn load(&mut self, tyl: TyLayout<'cx>, ptr_reg: Register, span: Span) -> Register {
         let reg = self.new_reg(None, tyl.clone());
         let stmt = StatementKind::Load {
             result: reg,
@@ -81,27 +86,27 @@ impl FuncBuilder {
             size: Operand::const_u64(tyl.layout.size),
             align: Operand::const_u64(tyl.layout.align),
         };
-        self.bb_mut()
+        self.cur_bb_mut()
             .statements
             .push(Statement { span, kind: stmt });
         reg
     }
 
-    pub fn store(&mut self, ptr_reg: Register, rhs: Operand, layout: Layout, span: Span) {
+    pub fn store(&mut self, ptr_reg: Register, rhs: Operand, layout: &Layout, span: Span) {
         let stmt = StatementKind::Store {
             ptr_reg,
             value: rhs,
             size: Operand::const_u64(layout.size),
             align: Operand::const_u64(layout.align),
         };
-        self.bb_mut()
+        self.cur_bb_mut()
             .statements
             .push(Statement { span, kind: stmt });
     }
 
     pub fn call(
         &mut self,
-        ret_tyl: TyLayout,
+        ret_tyl: TyLayout<'cx>,
         func: Operand,
         args: Vec<Operand>,
         span: Span,
@@ -112,18 +117,30 @@ impl FuncBuilder {
             func,
             args,
         };
-        self.bb_mut()
+        self.cur_bb_mut()
             .statements
             .push(Statement { span, kind: stmt });
         reg
     }
 
-    pub fn bb_mut(&mut self) -> &mut BasicBlock {
-        &mut self.ir.bbs[self.current_bb as usize]
+    pub fn bb_mut(&mut self, bb: BbIdx) -> &mut BasicBlock {
+        self.ir.bb_mut(bb)
     }
 
-    pub fn finish(mut self) -> Func {
-        self.bb_mut().term = Branch::Ret(Operand::Const(ConstValue::Void));
+    pub fn cur_bb_mut(&mut self) -> &mut BasicBlock {
+        &mut self.ir.bbs[self.current_bb.as_usize()]
+    }
+
+    pub fn new_block(&mut self) -> BbIdx {
+        self.ir.bbs.push(BasicBlock {
+            statements: vec![],
+            term: Branch::Goto(BbIdx(0)),
+        });
+        BbIdx::from_usize(self.ir.bbs.len() - 1)
+    }
+
+    pub fn finish(mut self) -> Func<'cx> {
+        self.cur_bb_mut().term = Branch::Ret(Operand::Const(ConstValue::Void));
 
         println!("{}", ir::func_to_string(&self.ir));
 
diff --git a/analysis/src/ty.rs b/analysis/src/ty.rs
index 9e04554..ee6a6b7 100644
--- a/analysis/src/ty.rs
+++ b/analysis/src/ty.rs
@@ -1,10 +1,18 @@
+use std::{
+    hash::{Hash, Hasher},
+    ops::Deref,
+};
+
 use indexmap::IndexMap;
 use parser::{ast::IntTy, Symbol};
 
 use crate::ir::DefId;
 
-#[derive(Debug, Clone)]
-pub enum Ty {
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Ty<'cx>(&'cx TyKind<'cx>);
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum TyKind<'cx> {
     Void,
     Char,
     SChar,
@@ -14,26 +22,55 @@ pub enum Ty {
     Double,
     LongDouble,
     Bool,
-    Ptr(Box<Ty>),
-    Union(UnionTy),
-    Struct(StructTy),
+    Ptr(Ty<'cx>),
+    Union(UnionTy<'cx>),
+    Struct(StructTy<'cx>),
     Enum(EnumTy),
 }
 
-#[derive(Debug, Clone)]
-pub struct UnionTy {
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct UnionTy<'cx> {
     pub def_id: DefId,
-    pub variants: IndexMap<Symbol, Ty>,
+    pub variants: IndexMap<Symbol, Ty<'cx>>,
 }
 
-#[derive(Debug, Clone)]
-pub struct StructTy {
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct StructTy<'cx> {
     pub def_id: DefId,
-    pub fields: IndexMap<Symbol, Ty>,
+    pub fields: IndexMap<Symbol, Ty<'cx>>,
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct EnumTy {
     pub def_id: DefId,
     pub variants: IndexMap<Symbol, i128>,
 }
+
+impl<'cx> Ty<'cx> {
+    pub fn new_unchecked(kind: &'cx TyKind<'cx>) -> Self {
+        Self(kind)
+    }
+}
+
+impl<'cx> Deref for Ty<'cx> {
+    type Target = &'cx TyKind<'cx>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl Hash for UnionTy<'_> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.def_id.hash(state)
+    }
+}
+impl Hash for StructTy<'_> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.def_id.hash(state)
+    }
+}
+impl Hash for EnumTy {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.def_id.hash(state)
+    }
+}
diff --git a/parser/src/ast.rs b/parser/src/ast.rs
index e736cc2..4fc3eff 100644
--- a/parser/src/ast.rs
+++ b/parser/src/ast.rs
@@ -142,7 +142,7 @@ pub enum Stmt {
 // --- Types and decls and garbage whatever
 //
 
-#[derive(Debug, DebugPls, Clone, Copy)]
+#[derive(Debug, DebugPls, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum IntTySignedness {
     Signed,
     Unsigned,
@@ -155,7 +155,7 @@ impl Default for IntTySignedness {
     }
 }
 
-#[derive(Debug, DebugPls, Clone, Copy)]
+#[derive(Debug, DebugPls, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum IntTyKind {
     Short,
     Int,
@@ -163,7 +163,7 @@ pub enum IntTyKind {
     LongLong,
 }
 
-#[derive(Debug, DebugPls, Clone, Copy)]
+#[derive(Debug, DebugPls, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct IntTy {
     pub sign: IntTySignedness,
     pub kind: IntTyKind,
diff --git a/src/main.rs b/src/main.rs
index a512adb..040b87a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -15,5 +15,7 @@ fn main() {
     printer.translation_unit(&ast).unwrap();
     println!("// END CODE    -------------------");
 
-    let _ = analysis::lower_translation_unit(&ast);
+    let arena = bumpalo::Bump::new();
+
+    let _ = analysis::lower_translation_unit(&arena, &ast);
 }