* net/loveruby/cflat/compiler/IRGenerator.java: generates IR (intermediate representation) tree (work is still incomplete but commit for logging).

* net/loveruby/cflat/ir: new package to hold IR tree nodes.
* net/loveruby/cflat/ir/IRTree.java: new class.
* net/loveruby/cflat/ir/Stmt.java: new class.
* net/loveruby/cflat/ir/StmtKind.java: new enum.
* net/loveruby/cflat/ir/Expr.java: new class.
* net/loveruby/cflat/ir/ExprKind.java: new enum.


git-svn-id: file:///Users/aamine/c/gitwork/public/cbc/trunk@4136 1b9489fe-b721-0410-924e-b54b9192deb8

ChangeLog

@@ -1,3 +1,21 @@
+Mon Apr 13 01:53:25 2009  Minero Aoki  <aamine@loveruby.net>
+
+	* net/loveruby/cflat/compiler/IRGenerator.java: generates IR
+	  (intermediate representation) tree (work is still incomplete but
+	  commit for logging).
+
+	* net/loveruby/cflat/ir: new package to hold IR tree nodes.
+
+	* net/loveruby/cflat/ir/IRTree.java: new class.
+
+	* net/loveruby/cflat/ir/Stmt.java: new class.
+
+	* net/loveruby/cflat/ir/StmtKind.java: new enum.
+
+	* net/loveruby/cflat/ir/Expr.java: new class.
+
+	* net/loveruby/cflat/ir/ExprKind.java: new enum.
+
 Sun Apr 12 17:49:19 2009  Minero Aoki  <aamine@loveruby.net>
 
 	* net/loveruby/cflat/compiler/TypeChecker.java: split IRGenerator.

net/loveruby/cflat/compiler/IRGenerator.java

@@ -1,12 +1,14 @@
 package net.loveruby.cflat.compiler;
 import net.loveruby.cflat.ast.*;
+import net.loveruby.cflat.ir.*;
 import net.loveruby.cflat.type.*;
 import net.loveruby.cflat.exception.*;
 import java.util.*;
 
-class IRGenerator extends Visitor {
+class IRGenerator extends ASTVisitor<Void, Expr> {
     protected ErrorHandler errorHandler;
     protected TypeTable typeTable;
+    private List<Stmt> stmts;
 
     // #@@range/ctor{
     public IRGenerator(ErrorHandler errorHandler) {
@@ -15,22 +17,24 @@ class IRGenerator extends Visitor {
     // #@@}
 
     protected void compile(StmtNode node) {
+        if (node == null) return;
         visitStmt(node);
     }
 
-    protected void compile(ExprNode node) {
-        visitExpr(node);
+    protected Expr compile(ExprNode node) {
+        if (node == null) return null;
+        return visitExpr(node);
     }
 
-    // FIXME: generate IR tree
     // #@@range/check_AST{
-    public AST compile(AST ast) throws SemanticException {
+    public IRTree compile(AST ast) throws SemanticException {
         typeTable = ast.typeTable();
-        for (DefinedVariable var : ast.definedVariables()) {
-            visit(var);
-        }
+        // FIXME: required?
+        //for (DefinedVariable var : ast.definedVariables()) { visit(var); }
         for (DefinedFunction f : ast.definedFunctions()) {
+            List<Stmt> stmts = new ArrayList<Stmt>();
             compile(f.body());
+            f.setIR(stmts);
         }
         if (errorHandler.errorOccured()) {
             throw new SemanticException("IR generation failed.");
@@ -39,52 +43,392 @@ class IRGenerator extends Visitor {
     }
     // #@@}
 
-    public Void visit(OpAssignNode node) {
-        super.visit(node);
-        if (node.operator().equals("+") || node.operator().equals("-")) {
-            if (node.lhs().type().isDereferable()) {
-                node.setRHS(multiplyPtrBaseSize(node.rhs(), node.lhs()));
+    //
+    // Statement
+    //
+
+    public Void visit(BlockNode node) {
+        for (DefinedVariable var : node.scope().localVariables()) {
+            if (var.initializer() != null) {
+                stmts.add(Stmt.move(Expr.var(var), compile(var.initializer())));
             }
         }
+        for (StmtNode s : node.stmts()) {
+            stmts.add(compile(s));
+        }
         return null;
     }
 
+    public Void visit(ExprStmtNode node) {
+        stmts.add(Stmt.stmt(compile(node.expr())));
+        return null;
+    }
+
+    public Void visit(ReturnNode node) {
+        stmts.add(Stmt.ret(compile(node.expr())));
+        return null;
+    }
+
+    public Void visit(IfNode node) {
+        stmts.add(Stmt.branch(compile(node.cond()),
+                                node.thenLabel(),
+                                node.elseLabel()));
+        stmts.add(Stmt.label(node.thenLabel()));
+        compile(node.thenBody());
+        stmts.add(Stmt.label(node.elseLabel()));
+        compile(node.elseBody());
+        stmts.add(Stmt.label(node.endLabel()));
+        return null;
+    }
+
+    // FIXME
+    public Void visit(SwitchNode node) {
+        throw new Error("switch not implemented yet");
+    }
+
+    public Void visit(WhileNode node) {
+        stmts.add(Stmt.branch(compile(node.cond()),
+                node.bodyLabel(), node.endLabel()));
+        stmts.add(Stmt.label(node.begLabel()));
+        compile(node.body());
+        stmts.add(Stmt.branch(compile(node.cond()),
+                node.begLabel(), node.endLabel()));
+        stmts.add(Stmt.label(node.endLabel()));
+        return null;
+    }
+
+    public Void visit(DoWhileNode node) {
+        stmts.add(Stmt.label(node.begLabel()));
+        compile(node.body());
+        stmts.add(Stmt.branch(compile(node.cond()),
+                node.begLabel(), node.endLabel()));
+        stmts.add(Stmt.label(node.endLabel()));
+        return null;
+    }
+
+    public Void visit(ForNode node) {
+        compile(node.init());
+        stmts.add(Stmt.branch(compile(node.cond()),
+                node.begLabel(), node.endLabel()));
+        stmts.add(node.begLabel());
+        compile(node.body());
+        stmts.add(node.continueLabel());
+        compile(node.incr());
+        stmts.add(Stmt.branch(compile(node.cond()),
+                node.begLabel(), node.endLabel()));
+        stmts.add(node.endLabel());
+        return null;
+    }
+
+    public Void visit(BreakNode node) {
+        stmts.add(Stmt.jump(currentBreakLabel()));
+        return null;
+    }
+
+    public Void visit(ContinueNode node) {
+        stmts.add(Stmt.jump(currentContinueLabel()));
+        return null;
+    }
+
+    public Void visit(GotoNode node) {
+        stmts.add(Stmt.jump(node.label()));
+        return null;
+    }
+
+    public Void visit(LabelNode node) {
+        stmts.add(node.label());
+        compile(node.stmt());
+        return null;
+    }
+
+    //
+    // RHS Expression
+    //
+
     // #@@range/BinaryOpNode{
-    public Void visit(BinaryOpNode node) {
-        super.visit(node);
+    public Expr visit(BinaryOpNode node) {
+        ExprKind op = binOp(node.operator());
+        Expr left = compile(node.left());
+        Expr right = compile(node.right());
         if (node.operator().equals("+") || node.operator().equals("-")) {
             if (node.left().type().isDereferable()) {
-                node.setRight(multiplyPtrBaseSize(node.right(), node.left()));
+                right = multiplyPtrBaseSize(right, node.left());
             }
             else if (node.right().type().isDereferable()) {
-                node.setLeft(multiplyPtrBaseSize(node.left(), node.right()));
+                left = multiplyPtrBaseSize(left, node.right());
             }
         }
-        return null;
+        return Expr.bin(op, left, right);
     }
     // #@@}
 
-    protected BinaryOpNode multiplyPtrBaseSize(ExprNode expr, ExprNode ptr) {
-        return new BinaryOpNode(expr, "*", ptrBaseSize(ptr));
+    public Expr visit(AssignNode node) {
+        Expr tmp = Expr.tmp();
+        return Expr.seq(
+            Stmt.seq(
+                Stmt.move(tmp, compile(node.rhs())),
+                Stmt.move(compileLHS(node.lhs()), tmp)
+            ),
+            tmp);
     }
 
-    protected IntegerLiteralNode ptrBaseSize(ExprNode ptr) {
-        return integerLiteral(ptr.location(),
-                              typeTable.ptrDiffTypeRef(),
-                              ptr.type().baseType().size());
+    public Expr visit(OpAssignNode node) {
+        Expr r = Expr.tmp();
+        Expr l = Expr.tmp();
+        return Expr.seq(
+            Stmt.seq(
+                Stmt.move(r, compileOpAssignRHS(node.rhs()),
+                Stmt.move(l, compileLHS(node.lhs())),
+                Stmt.move(Expr.mem(l),
+                        Expr.bin(binOp(node.operator()),
+                            Expr.mem(l), r))
+            ),
+            r);
     }
 
-    protected IntegerLiteralNode integerLiteral(Location loc, TypeRef ref, long n) {
-        IntegerLiteralNode node = new IntegerLiteralNode(loc, ref, n);
-        bindType(node.typeNode());
-        return node;
+    private Expr compileOpAssignRHS(String op, ExprNode rhs, ExprNode lhs) {
+        if ((op.equals("+") || op.equals("-")) && lhs.type().isDereferable()) {
+            return multiplyPtrBaseSize(compile(rhs), lhs);
+        }
+        else {
+            return compile(rhs);
+        }
     }
 
-    protected void bindType(TypeNode t) {
-        t.setType(typeTable.get(t.typeRef()));
+    protected Expr multiplyPtrBaseSize(Expr expr, ExprNode ptr) {
+        return Expr.bin(ExprKind.MUL, expr, ptrBaseSize(ptr));
     }
 
-    protected void error(Node n, String msg) {
+    protected Expr ptrBaseSize(ExprNode ptr) {
+        Type t = typeTable.ptrDiffType();
+        Location loc = ptr.location();
+        return Expr.const(ptr.type().baseType().size());
+    }
+
+    public Expr visit(LogicalAndNode node) {
+        Expr l = Expr.tmp();
+        Expr result = Expr.tmp();
+        return Expr.seq(
+            Stmt.seq(
+                Stmt.move(l, compile(node.left())),
+                Stmt.branch(l, node.thenLabel(), node.elseLabel()),
+                Stmt.label(node.thenLabel()),
+                Stmt.move(result, l),
+                Stmt.label(node.elseLabel()),
+                Stmt.move(result, compile(node.right()))
+            ),
+            result);
+    }
+
+    public Expr visit(LogicalOrNode node) {
+        Expr l = Expr.tmp();
+        Expr result = Expr.tmp();
+        return Expr.seq(
+            Stmt.seq(
+                Stmt.move(l, compile(node.left())),
+                Stmt.branch(l, node.elseLabel(), node.thenLabel()),
+                Stmt.label(node.thenLabel()),
+                Stmt.move(result, l),
+                Stmt.label(node.elseLabel()),
+                Stmt.move(result, compile(node.right()))
+            ),
+            result);
+    }
+
+    public Expr visit(CondExprNode node) {
+        Expr result = Expr.tmp();
+        return Expr.seq(
+            Stmt.seq(
+                Stmt.branch(compile(node.cond()),
+                        node.thenLabel(), node.elseLabel()),
+                Stmt.label(node.thenLabel()),
+                Stmt.move(result, compile(node.thenExpr())),
+                Stmt.label(node.elseLabel()),
+                Stmt.move(result, compile(node.elseExpr()))
+            ),
+            result);
+    }
+
+    public Expr visit(FuncallNode node) {
+        List<Expr> args = new ArrayList<Expr>();
+        for (ExprNode a : node.arguments()) {
+            args.add(compile(a));
+        }
+        return Expr.call(compile(node.expr()), args);
+    }
+
+    public Expr visit(UnaryOpNode node) {
+        if (node.operator().equals("+")) {
+            return compile(node.expr());
+        }
+        else {
+            return Expr.uni(uniOp(node.operator()), compile(node.expr()));
+        }
+    }
+
+    public Expr visit(PrefixOpNode node) {
+        Expr lhs = Expr.tmp();
+        return Expr.seq(
+            Stmt.seq(
+                Stmt.move(lhs, compileLHS(node.expr())),
+                Stmt.move(Expr.mem(lhs),
+                    Expr.bin(uniOp(node.operator()),
+                            Expr.mem(lhs),
+                            Expr.const(1)))
+            ),
+            Expr.mem(lhs));
+    }
+
+    public Expr visit(SuffixOpNode node) {
+        Expr lhs = Expr.tmp();
+        Expr save = Expr.tmp();
+        return Expr.seq(
+            Stmt.seq(
+                Stmt.move(lhs, compileLHS(node.expr())),
+                Stmt.move(save, Expr.mem(lhs));
+                Stmt.move(Expr.mem(lhs),
+                    Expr.bin(uniOp(node.operator()),
+                            Expr.mem(lhs),
+                            Expr.const(1)))
+            ),
+            Expr.mem(save));
+    }
+
+    public Expr visit(AddressNode node) {
+        return compileLHS(node.expr());
+    }
+
+    public Expr visit(SizeofExprNode node) {
+        return Expr.const(node.expr().type().allocSize());
+    }
+
+    public Expr visit(SizeofTypeNode node) {
+        return Expr.const(node.operand().allocSize());
+    }
+
+    public Expr visit(IntegerLiteralNode node) {
+        return Expr.const(node.value());
+    }
+
+    public Expr visit(StringLiteralNode node) {
+        return Expr.name(node.entry());
+    }
+
+    //
+    // Assignable Expression as RHS
+    //
+
+    public Expr visit(ArefNode node) {
+        return Expr.mem(compileLHS(node));
+    }
+
+    public Expr visit(MemberNode node) {
+        Expr a = Expr.add(Expr.const(node.offset()), compileLHS(node.expr()));
+        return node.shouldEvaluatedToAddress() ? a : Expr.deref(a);
+    }
+
+    public Expr visit(PtrMemberNode node) {
+        Expr addr = Expr.add(Expr.const(node.offset()), compile(node.expr()));
+        return node.shouldEvaluatedToAddress() ? addr : Expr.deref(addr);
+    }
+
+    public Expr visit(DereferenceNode node) {
+        return Expr.deref(compile(node.expr()));
+    }
+
+    public Expr visit(VariableNode node) {
+        return Expr.var(node.variable());
+    }
+
+    //
+    // Assignable Expression as LHS
+    //
+
+    public Expr compileLHS(ExprNode node) {
+        node.acceptLHS(this);
+    }
+
+    public Expr visitLHS(VariableNode node) {
+        return addressOf(node);
+    }
+
+    public Expr visitLHS(ArefNode node) {
+        return Expr.add(
+            Expr.mul(
+                Expr.const(node.elementSize()),
+                compileArrayIndex(node)),
+            compile(node.baseExpr));
+    }
+
+    private Expr compileArrayIndex(ArefNode node) {
+        if (node.isMultiDimension()) {
+            return Expr.add(
+                compile(node.index()),
+                Expr.mul(
+                    Expr.const(node.length()),
+                    compileArrayIndex((ArefNode)node.expr())));
+        }
+        else {
+            return compile(node.index());
+        }
+    }
+
+    public Expr visitLHS(MemberNode node) {
+        return Expr.add(
+            Expr.const(node.offset()),
+            compileLHS(node.expr()));
+    }
+
+    public Expr visitLHS(PtrMemberNode node) {
+        return Expr.add(
+            Expr.const(node.offset()),
+            compile(node.expr()));
+    }
+
+    public Expr visitLHS(DereferenceNode node) {
+        return compile(node.expr());
+    }
+
+    //
+    // Utilities
+    //
+
+    private Expr addressOf(VariableNode node) {
+    }
+
+    private Expr addressOf(StringLiteralNode node) {
+    }
+
+    private ExprKind uniOp(String op) {
+        if (op.equals("-")) return ExprKind.UMINUS;
+        if (op.equals("~")) return ExprKind.NOT;
+        if (op.equals("!")) return ExprKind.LNOT;
+        if (op.equals("*")) return ExprKind.DEREF;
+        if (op.equals("++")) return ExprKind.ADD;
+        if (op.equals("--")) return ExprKind.SUB;
+    }
+
+    // FIXME: signed, arithmetic shift
+    private ExprKind binOp(String op) {
+        if (op.equals("+")) return ExprKind.ADD;
+        if (op.equals("-")) return ExprKind.SUB;
+        if (op.equals("*")) return ExprKind.MUL;
+        if (op.equals("/")) return ExprKind.DIV;
+        if (op.equals("%")) return ExprKind.MOD;
+        if (op.equals("&")) return ExprKind.AND;
+        if (op.equals("|")) return ExprKind.OR;
+        if (op.equals("^")) return ExprKind.XOR;
+        if (op.equals("<<")) return ExprKind.LSHIFT;
+        if (op.equals(">>")) return ExprKind.RSHIFT;
+        if (op.equals("==")) return ExprKind.EQ;
+        if (op.equals("!=")) return ExprKind.NEQ;
+        if (op.equals("<")) return ExprKind.LT;
+        if (op.equals("<=")) return ExprKind.LTEQ;
+        if (op.equals(">")) return ExprKind.GT;
+        if (op.equals(">=")) return ExprKind.GTEQ;
+    }
+
+    private void error(Node n, String msg) {
         errorHandler.error(n.location(), msg);
     }
 }

net/loveruby/cflat/ir/Expr.java

@@ -0,0 +1,82 @@
+package net.loveruby.cflat.ir;
+
+public class Expr {
+    protected ExprKind kind;
+    protected Expr x, y;
+    protected List<Expr> args;
+    protected long value;
+    protected ConstantEntry entry;
+    protected Entity entity;
+    protected Stmt stmt;
+
+    static public const(long value) {
+        return new Expr(ExprKind.CONST, null, null, null, value, null, null, null);
+    }
+
+    static public name(ConstantEntry entry) {
+        return new Expr(ExprKind.NAME, null, null, null, 0, entry, null, null);
+    }
+
+    static public var(Entity entity) {
+        return new Expr(ExprKind.VAR, null, null, null, 0, null, entity, null);
+    }
+
+    static public varAddr(Entity entity) {
+        return new Expr(ExprKind.VARADDR, null, null, null, 0, null, entity, null);
+    }
+
+    static public call(Expr f, List<Expr> args) {
+        return new Expr(ExprKind.CALL, f, null, args, 0, null, null, null);
+    }
+
+    static public uni(ExprKind t, Expr expr) {
+        return new Expr(t, expr, null, null, 0, null, null, null);
+    }
+
+    static public bin(ExprKind t, Expr left, Expr right) {
+        return new Expr(t, left, right, null, 0, null, null, null);
+    }
+
+    static public add(Expr left, Expr right) {
+        return new Expr(ExprKind.ADD, left, right, null, 0, null, null, null);
+    }
+
+    static public mul(Expr left, Expr right) {
+        return new Expr(ExprKind.MUL, left, right, null, 0, null, null, null);
+    }
+
+    static public seq(Stmt s, Expr e) {
+        return new Expr(ExprKind.SEQ, e, null, null, 0, nul, null, s);
+    }
+
+    public Expr(ExprKind k, Expr x, Expr y, List<Expr> args,
+            long value, ConstantEntry entry, Entity entity, Stmt stmt) {
+        this.kind = k;
+        this.x = x;
+        this.y = y;
+        this.args = args;
+        this.value = value;
+        this.entry = entry;
+        this.entity = entity;
+        this.stmt = stmt;
+    }
+
+    // as primary
+    public long value() { return value; }
+    public ConstantEntry entry() { return entry; }
+    public Entity entity() { return entity; }
+
+    // as unary
+    public Expr expr() { return x; }
+
+    // as binary
+    public Expr left() { return x; }
+    public Expr right() { return y; }
+
+    // as seq
+    public Stmt stmt() { return stmt; }
+
+    // as call
+    public Expr function() { return x; }
+    public List<Expr> args() { return args; }
+}

net/loveruby/cflat/ir/ExprKind.java

@@ -0,0 +1,33 @@
+package net.loveruby.cflat.ir;
+
+public enum ExprKind {
+    // primary
+    CONST,      // integer constant
+    NAME,       // assembly name (string literal, global variable)
+    VAR,        // variable
+    VARADDR,    // address of variable
+    // unary
+    UMINUS,     // unary minus
+    NOT,        // bitwise not
+    LNOT,       // logical not
+    DEREF,      // dereference
+    // binary
+    ADD,        // addition
+    SUB,        // subtract
+    MUL,        // multiplication
+    DIV,        // division
+    MOD,        // modulo
+    AND,        // bitwise and
+    OR,         // bitwise or
+    XOR,        // bitwise xor
+    LSHIFT,     // left shift
+    RSHIFT,     // right shift
+    EQ,         // ==
+    NEQ,        // !=
+    GT,         // >
+    GTEQ,       // >=
+    LT,         // <
+    LTEQ,       // <=
+    // seq
+    SEQ;        // expression sequence (for +=, ++, --)
+}

net/loveruby/cflat/ir/IRTree.java

@@ -0,0 +1,21 @@
+package net.loveruby.cflat.ir;
+
+public class IRTree {
+    protected Location source;
+    protected ToplevelScope scope;
+    protected ConstantTable constantTable;
+    protected Set<DefinedVariable> defvars;
+    protected Set<DefinedFunction> defuns;
+
+    public IRTree(Location source,
+            ToplevelScope scope,
+            ConstantTable constants,
+            Set<DefinedVariable> defvars,
+            Set<DefinedFunction> defuns) {
+        this.source = source;
+        this.scope = scope;
+        this.constants = constants;
+        this.defvars = defvars;
+        this.defuns = defuns;
+    }
+}

net/loveruby/cflat/ir/Stmt.java

@@ -0,0 +1,82 @@
+package net.loveruby.cflat.ir;
+
+public class Stmt {
+    protected StmtKind kind;
+    protected Expr x, y;
+    protected Stmt car, cdr;
+    protected Label thenDest, elseDest;
+
+    static public Stmt move(Expr lhs, Expr rhs) {
+        return new Stmt(StmtKind.MOVE, lhs, rhs, null, null);
+    }
+
+    static public Stmt branch(Expr cond, Label thenDest, elseDest) {
+        return new Stmt(StmtKind.BRANCH, cond, null, null, null, thenDest, elseDest);
+    }
+
+    static public Stmt stmt(Expr expr) {
+        return new Stmt(StmtKind.EXPR, expr, null, null, null, null, null);
+    }
+
+    static public Stmt ret(Expr expr) {
+        return new Stmt(StmtKind.RETURN, expr, null, null, null, null, null);
+    }
+
+    static public Stmt label(Label label) {
+        return new Stmt(StmtKind.LABEL, null, null, null, null, label, null);
+    }
+
+    static public Stmt seq(Stmt car, Stmt cdr) {
+        return new Stmt(StmtKind.SEQ, null, null, car, cdr, null, null);
+    }
+
+    static public Stmt seq(Stmt s1, Stmt s2, Stmt s3) {
+        return seq(s1, seq(s2, s3));
+    }
+
+    static public Stmt seq(Stmt s1, Stmt s2, Stmt s3, Stmt s4) {
+        return seq(s1, seq(s2, seq(s3, s4)));
+    }
+
+    static public Stmt seq(Stmt s1, Stmt s2, Stmt s3, Stmt s4, Stmt s5) {
+        return seq(s1, seq(s2, seq(s3, seq(s4, s5))));
+    }
+
+    static public Stmt seq(Stmt s1, Stmt s2, Stmt s3, Stmt s4, Stmt s5, Stmt s6) {
+        return seq(s1, seq(s2, seq(s3, seq(s4, seq(s5, s6)))));
+    }
+
+    static public Stmt seq(Stmt s1, Stmt s2, Stmt s3, Stmt s4, Stmt s5, Stmt s6, Stmt s7) {
+        return seq(s1, seq(s2, seq(s3, seq(s4, seq(s5, seq(s6, s7))))));
+    }
+
+    public Stmt(StmtKind kind, Expr x, Expr y,
+            Stmt car, Stmt cdr,
+            Label thenDest, Label elseDest) {
+        this.kind = kind;
+        this.x = x;
+        this.y = y;
+        this.car = car;
+        this.cdr = cdr;
+        this.thenDest = thenDest;
+        this.elseDest = elseDest;
+    }
+
+    public StmtKind kind() { return kind; }
+
+    // as expr-statement, return
+    public Expr expr() { return x; }
+
+    // as move
+    public Expr lhs() { return x; }
+    public Expr rhs() { return y; }
+
+    // as branchIf
+    public Expr cond() { return x; }
+    public Label thenDest() { return thenDest; }
+    public Label elseDest() { return elseDest; }
+
+    // as seq
+    public Stmt car() { return car; }
+    public Stmt cdr() { return cdr; }
+}

net/loveruby/cflat/ir/StmtKind.java

@@ -0,0 +1,9 @@
+package net.loveruby.cflat.ir;
+
+public enum StmtKind {
+    MOVE,       // assignment
+    EXPR,       // expression statement
+    BRANCH,     // conditional jump
+    RETURN,     // return
+    LABEL;      // label
+}