diff --git a/python/src/triton.cc b/python/src/triton.cc
index 27a31b981..66cece243 100644
--- a/python/src/triton.cc
+++ b/python/src/triton.cc
@@ -659,12 +659,35 @@ void init_triton_ir(py::module &&m) {
   py::class_<mlir::BlockArgument, mlir::Value>(m, "block_arguement")
       ;
 
+  py::class_<mlir::Region>(m, "region")
+      .def("get_parent_region", &mlir::Region::getParentRegion, ret::reference)
+      .def("size", [](mlir::Region &self) {
+        return self.getBlocks().size();
+      })
+      ;
+
   py::class_<mlir::Block>(m, "block")
       .def("arg", [](mlir::Block &self, int index) -> mlir::BlockArgument {
         return self.getArgument(index);
       })
       .def("dump", &mlir::Block::dump)
       .def("move_before", &mlir::Block::moveBefore)
+      .def("insert_before", &mlir::Block::insertBefore)
+      .def("get_parent", &mlir::Block::getParent, ret::reference)
+      .def("merge_block_before", [](mlir::Block &self, mlir::Block &dst) {
+        // ref: RewriterBase::mergeBlocks()
+        if (self.getNumArguments() != 0)
+          throw std::runtime_error("This block has arguments, don't merge");
+        dst.getOperations().splice(dst.end(), self.getOperations());
+        self.dropAllUses();
+        self.erase();
+      })
+      .def("replace_use_in_block_with", [](mlir::Block &self, mlir::Value &v, mlir::Value &newVal) {
+        v.replaceUsesWithIf(newVal, [&](mlir::OpOperand &operand){
+          mlir::Operation *user = operand.getOwner();
+          return user->getBlock() == &self;
+        });
+      })
       ;
 
   // py::class_<mlir::ModuleOp>(m, "module")
@@ -713,12 +736,13 @@ void init_triton_ir(py::module &&m) {
       .def("get_region", [](mlir::OpState &self, unsigned idx) -> mlir::Region& {
         return self->getRegion(idx);
       }, ret::reference)
+      .def("get_body", [](mlir::scf::ForOp &self, unsigned idx) -> mlir::Block* {
+        return self.getBody(idx);
+      }, ret::reference)
+      .def("dump", [](mlir::OpState &self) { self->dump(); })
       ;
   // scf Ops
-  py::class_<mlir::scf::ForOp, mlir::OpState>(m, "ForOp")
-      .def("get_body", [](mlir::scf::ForOp &self) -> mlir::Block* {
-        return self.getBody();
-      }, ret::reference);
+  py::class_<mlir::scf::ForOp, mlir::OpState>(m, "ForOp");
   py::class_<mlir::scf::IfOp, mlir::OpState>(m, "IfOp")
       .def("get_then_block", &mlir::scf::IfOp::thenBlock, ret::reference)
       .def("get_else_block", &mlir::scf::IfOp::elseBlock, ret::reference)
@@ -856,11 +880,14 @@ void init_triton_ir(py::module &&m) {
         mlir::Region *parent = self.getBlock()->getParent();
         return self.createBlock(parent);
       }, ret::reference)
+      .def("new_block", [](mlir::OpBuilder &self) -> mlir::Block* {
+        return new mlir::Block();
+      }, ret::reference)
       // Structured control flow
       .def("create_for_op", [](mlir::OpBuilder &self, mlir::Value &lb, mlir::Value &ub,
                                mlir::Value &step, std::vector<mlir::Value> &initArgs) -> mlir::scf::ForOp {
         auto loc = self.getUnknownLoc();
-        return self.create<mlir::scf::ForOp>(loc, lb, ub, step);
+        return self.create<mlir::scf::ForOp>(loc, lb, ub, step, initArgs);
       })
       .def("create_if_of", [](mlir::OpBuilder &self, mlir::Value &condition) -> mlir::scf::IfOp {
         auto loc = self.getUnknownLoc();
diff --git a/python/triton/code_gen.py b/python/triton/code_gen.py
index 5890d7358..dcf038136 100644
--- a/python/triton/code_gen.py
+++ b/python/triton/code_gen.py
@@ -195,7 +195,6 @@ class CodeGenerator(ast.NodeVisitor):
         assert len(_names) == 1
         names = _names[0]
         values = self.visit(node.value)
-        print(f'visit_Assign({names}, {values})')
         if not isinstance(names, tuple):
             names = [names]
         if not isinstance(values, tuple):
@@ -440,34 +439,30 @@ class CodeGenerator(ast.NodeVisitor):
                     init_args.append(triton.language.core._to_tensor(liveins[name], self.builder))
                     yields.append(triton.language.core._to_tensor(self.local_defs[name], self.builder))
 
-        print(f'names: {names}')
-        print("After insert block body")
-        self.module.dump()
         self.builder.set_insertion_point_to_end(insert_block)
         for_op = self.builder.create_for_op(lb, ub, step, [arg.handle for arg in init_args])
-        print("After create for op")
-        self.module.dump()
-        # TODO: revisit blocks & regions of ForOp
-        block.move_before(for_op.get_body())
-        self.builder.set_insertion_point_to_end(for_op.get_body())
+        # FIXME: the body should be a region (?)
+        # FIXME: this won't work for nested control flow
+        block.merge_block_before(for_op.get_body(0))
+        self.builder.set_insertion_point_to_end(for_op.get_body(0))
         self.builder.create_yield_op([y.handle for y in yields])
-        print("After create yield op")
-        self.module.dump()
-        
+        for_op_region = for_op.get_body(0).get_parent()
+        assert for_op_region.size() == 1, "(For developer) Should use region here"
+        for i, name in enumerate(names):
+            # arg0 is the induction variable
+            for_op.get_body(0).replace_use_in_block_with(init_args[i].handle, for_op.get_body(0).arg(i+1))
 
         self.builder.set_insertion_point_to_end(insert_block)
-        print("After restoring insert point")
-        self.module.dump()
 
         self.lscope = liveins
         self.local_defs = prev_defs
         # ForOp defines new values
         for i, name in enumerate(names):
-            self.lscope[name] = for_op.get_result(i)
-            self.local_defs[name] = for_op.get_result(i)
+            self.lscope[name] = triton.language.core.tensor(for_op.get_result(i), yields[i].type)
+            self.local_defs[name] = triton.language.core.tensor(for_op.get_result(i), yields[i].type)
 
         for stmt in node.orelse:
-            assert False
+            assert False, "Don't know what to do with else after for"
             ast.NodeVisitor.generic_visit(self, stmt)
 
     def visit_Slice(self, node):