diff --git a/examples/matrix.cpp b/examples/matrix.cpp
index 0bc553849..9bf15ba00 100644
--- a/examples/matrix.cpp
+++ b/examples/matrix.cpp
@@ -2,6 +2,9 @@
 #include <cstdio>
 #include "ast.h"
 #include "codegen.h"
+#include "llvm/IR/IRPrintingPasses.h"
+#include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/PassManager.h"
 
 typedef struct yy_buffer_state * YY_BUFFER_STATE;
 extern int yyparse();
@@ -14,6 +17,8 @@ const char src[] =
 "\
 void test(fp32 *A, fp32 *B, fp32 *C){\
   int32 i = 0;\
+  int32 j = 1;\
+  i = i + j;\
 }\
 ";
 
@@ -25,5 +30,8 @@ int main() {
    tdl::context context;
    tdl::module module("matrix", &context);
    program->codegen(&module);
+   llvm::PrintModulePass print(llvm::outs());
+   llvm::AnalysisManager<llvm::Module> analysis;
+   print.run(*module.handle(), analysis);
    return 0;
 }
diff --git a/include/ast.h b/include/ast.h
index 031c974c1..1359c761b 100644
--- a/include/ast.h
+++ b/include/ast.h
@@ -192,25 +192,18 @@ public:
 };
 
 class assignment_expression: public expression{
-private:
-  llvm::Value *llvm_op(llvm::IRBuilder<> &builder,
-                       llvm::Value *lvalue, llvm::Value *rvalue,
-                       const std::string &name) const;
-
 public:
   assignment_expression(node *lvalue, ASSIGN_OP_T op, node *rvalue)
-    : lvalue_((expression*)lvalue), op_(op), rvalue_((expression*)rvalue) { }
+    : lvalue_((identifier*)lvalue), op_(op), rvalue_((expression*)rvalue) { }
 
   llvm::Value* codegen(module *mod) const;
 
 public:
   ASSIGN_OP_T op_;
-  const expression *lvalue_;
+  const identifier *lvalue_;
   const expression *rvalue_;
 };
 
-class statement: public node{
-};
 
 class initializer;
 class declaration_specifier;
@@ -227,6 +220,8 @@ public:
   const list<initializer*> *init_;
 };
 
+class statement: public node{
+};
 
 class compound_statement: public statement{
   typedef list<declaration*>* declarations_t;
diff --git a/include/codegen.h b/include/codegen.h
index e81c8cd01..87a6e0f30 100644
--- a/include/codegen.h
+++ b/include/codegen.h
@@ -18,6 +18,8 @@ private:
 
 class module {
   typedef std::pair<const ast::node*, llvm::BasicBlock*> val_key_t;
+  llvm::PHINode *make_phi(llvm::Type *type, unsigned num_values, llvm::BasicBlock *block);
+  llvm::Value *add_phi_operands(const ast::node *node, llvm::PHINode *&phi);
   llvm::Value *get_value_recursive(const ast::node* node, llvm::BasicBlock *block);
 
 public:
@@ -30,13 +32,15 @@ public:
   // Getters
   llvm::Value *get_value(const ast::node *node, llvm::BasicBlock* block);
   llvm::Value *get_value(const ast::node *node);
+  // Seal block -- no more predecessors will be added
+  llvm::Value *seal_block(llvm::BasicBlock *block);
 
 private:
   llvm::Module handle_;
   llvm::IRBuilder<> builder_;
   std::map<val_key_t, llvm::Value*> values_;
   std::set<llvm::BasicBlock*> sealed_blocks_;
-  std::map<val_key_t, llvm::PHINode*> incomplete_phis_;
+  std::map<llvm::BasicBlock*, std::map<const ast::node*, llvm::PHINode*>> incomplete_phis_;
 };
 
 
diff --git a/lib/codegen.cpp b/lib/codegen.cpp
index ac23557f0..9657a2c7a 100644
--- a/lib/codegen.cpp
+++ b/lib/codegen.cpp
@@ -37,22 +37,37 @@ void module::set_value(const ast::node* node, llvm::Value* value){
   return set_value(node, builder_.GetInsertBlock(), value);
 }
 
+PHINode* module::make_phi(Type *type, unsigned num_values, BasicBlock *block){
+  llvm::BasicBlock::iterator save = builder_.GetInsertPoint();
+  builder_.SetInsertPoint(&*block->getFirstInsertionPt());
+  PHINode *res = builder_.CreatePHI(type, num_values);
+  builder_.SetInsertPoint(&*save);
+  return res;
+}
+
+Value *module::add_phi_operands(const ast::node *node, PHINode *&phi){
+  BasicBlock *block = phi->getParent();
+  for(BasicBlock *pred: predecessors(block)){
+    llvm::Value *value = get_value(node, pred);
+    if(phi->getType()==nullptr){
+      phi = make_phi(value->getType(), pred_size(block), block);
+    }
+    phi->addIncoming(value, pred);
+  }
+}
+
 llvm::Value *module::get_value_recursive(const ast::node* node, BasicBlock *block) {
   llvm::Value *result;
   if(sealed_blocks_.find(block) == sealed_blocks_.end()){
-    result = builder_.CreatePHI(nullptr, 1);
-    incomplete_phis_[val_key_t(node, block)] = (PHINode*)result;
+    incomplete_phis_[block][node] = make_phi(nullptr, 1, block);
   }
   else if(pred_size(block) <= 1){
     result = get_value(node, *pred_begin(block));
   }
   else{
-    result = builder_.CreatePHI(nullptr, 1);
+    result = make_phi(nullptr, 1, block);
     set_value(node, block, result);
-    for(BasicBlock *pred: predecessors(block)){
-      llvm::Value *value = get_value(node, pred);
-      static_cast<PHINode*>(result)->addIncoming(value, pred);
-    }
+    add_phi_operands(node, (PHINode*&)result);
   }
   set_value(node, block, result);
 }
@@ -68,6 +83,11 @@ llvm::Value *module::get_value(const ast::node *node) {
   return get_value(node, builder_.GetInsertBlock());
 }
 
+llvm::Value *module::seal_block(BasicBlock *block){
+  for(auto &x: incomplete_phis_[block])
+    add_phi_operands(x.first, x.second);
+  sealed_blocks_.insert(block);
+}
 
 namespace ast{
 
@@ -170,7 +190,8 @@ Value* function_definition::codegen(module *mod) const{
 /* Statements */
 Value* compound_statement::codegen(module* mod) const{
   decls_->codegen(mod);
-//  statements_->codegen(mod);
+  if(statements_)
+    statements_->codegen(mod);
   return nullptr;
 }
 
@@ -456,15 +477,10 @@ Value *conditional_expression::codegen(module *mod) const{
 }
 
 /* Assignment expression */
-Value *assignment_expression::llvm_op(llvm::IRBuilder<> &builder, Value *lvalue, Value *rvalue, const std::string &name) const{
-  return nullptr;
-}
-
 Value *assignment_expression::codegen(module *mod) const{
-  Value *lvalue = lvalue_->codegen(mod);
   Value *rvalue = rvalue_->codegen(mod);
-  BasicBlock *block = mod->builder().GetInsertBlock();
-  return llvm_op(mod->builder(), lvalue, rvalue, "");
+  mod->set_value(lvalue_, rvalue);
+  return rvalue;
 }
 
 /* Type name */