Project 1 Hints Jingke Li Portland State University Jingke Li (Portland State University) CS322 Project 1 Hints 1 / 10 Basic Information The Compiler Infrastructure -- Same as last term's: ast/ --- the source-language's AST nodes symbol/ --- the symbol table package checker/ --- the typechecking package astpsr/ --- the AST parser program tst/ --- a set of test programs IR Tree Nodes -- In the ir/ subdirectory: One top-level abstract class, IR, for gluing all three nodes together. Two additional abstract classes, EXP and STMT, for grouping expressions and statements, respectively. A pre-defined dumping routine for each tree node, allowing a tree to be seen externally, e.g.: package ir; public class VAR extends EXP { public int idx; public VAR(int i) { idx=i; } public void dump() { DUMP(&quot; (VAR &quot; + idx + &quot;)&quot;); } } Jingke Li (Portland State University) CS322 Project 1 Hints 2 / 10 The IR-Gen Visitor Interface The IR code generator is to be implemented as a visitor pattern over the AST nodes. package ast; ... public interface TransVI { // Note: there is no need to translate type decl nodes public PROG visit(Program n) <a href="/keyword/throws-exception/" >throws exception</a> ; public FUNClist visit(ClassDeclList n) <a href="/keyword/throws-exception/" >throws exception</a> ; public FUNClist visit(ClassDecl n) <a href="/keyword/throws-exception/" >throws exception</a> ; ... public STMTlist visit(StmtList n) <a href="/keyword/throws-exception/" >throws exception</a> ; public STMT visit(Block n) <a href="/keyword/throws-exception/" >throws exception</a> ; ... public EXPlist visit(ExpList n) <a href="/keyword/throws-exception/" >throws exception</a> ; public EXP visit(Binop n) <a href="/keyword/throws-exception/" >throws exception</a> ; ... public EXP visit(Int n); public EXP visit(Real n); ... } Jingke Li (Portland State University) CS322 Project 1 Hints 3 / 10 Implementation Guidance Understand the pseudo-code template for each AST node; generate the IR code according to the template Pay attention to the structure of each AST node, and make proper recursive calls to the children nodes if needed Pay attention to the return value type of each node; properly assemble the results from children nodes Jingke Li (Portland State University) CS322 Project 1 Hints 4 / 10 Implementation -- Top-Level package ir; ... public class IrgenVisitor1 implements TransVI { private symbol.Table symTable; // needed to lookup class info private symbol.Class currClass; // tracking scope info private symbol.Method currMethod; // tracking scope info private CONST cOne, cZero // defined for convenience private NAME cWordSize; // a symbolic name public IrgenVisitor1(symbol.Table tab) { symTable = tab; cOne = new CONST(1); cZero = new CONST(0); cWordSize = new NAME(&quot;wSZ&quot;); } public PROG visit(Program n) <a href="/keyword/throws-exception/" >throws exception</a> { FUNClist funcs = n.cl.accept(this); return new PROG(funcs); } ... } Jingke Li (Portland State University) CS322 Project 1 Hints 5 / 10 Implementation -- Declarations (Some solutions are partial, and will be fixed in proj2.) public FUNClist visit(ClassDeclList n) <a href="/keyword/throws-exception/" >throws exception</a> { FUNClist funcs = new FUNClist(); for (int i = 0; i &lt; n.size(); i++) funcs.addAll(n.elementAt(i).accept(this)); return funcs; } public STMTlist visit(VarDeclList n) <a href="/keyword/throws-exception/" >throws exception</a> { // Each VarDecl returns a STMT or null; have to think how to // compose a STMTlist in the end } public FUNClist visit(ClassDecl n) <a href="/keyword/throws-exception/" >throws exception</a> { currClass = ... FUNClist funcs = n.ml.accept(this); currClass = null; return funcs; } public FUNC visit(MethodDecl n) <a href="/keyword/throws-exception/" >throws exception</a> { ... return new FUNC(label, 0, 0, stmts); } Jingke Li (Portland State University) CS322 Project 1 Hints ... 6 / 10 Implementation -- Statements (Some solutions are partial, and will be fixed in proj2.) public STMT visit(Block n) <a href="/keyword/throws-exception/" >throws exception</a> { return n.sl.accept(this); } public STMT visit(Assign n) <a href="/keyword/throws-exception/" >throws exception</a> { EXP lhs = n.lhs.accept(this); EXP rhs = n.rhs.accept(this); return new MOVE(lhs, rhs); } public STMT visit(CallStmt n) <a href="/keyword/throws-exception/" >throws exception</a> { ... return new CALLST(new NAME(label), el); } public STMT visit(If n) <a href="/keyword/throws-exception/" >throws exception</a> { ... implement according to the pseudo template } public STMT visit(While n) <a href="/keyword/throws-exception/" >throws exception</a> { ... implement according to the pseudo template } public STMT visit(Print n) <a href="/keyword/throws-exception/" >throws exception</a> { ... return a CALLST node to &quot;prString&quot; or &quot;prInt&quot; } ... Jingke Li (Portland State University) CS322 Project 1 Hints 7 / 10 Implementation -- Expressions (Some solutions are partial, and will be fixed in proj2.) public EXPlist visit(ExpList n) <a href="/keyword/throws-exception/" >throws exception</a> { return null; } public EXP visit(Binop n) <a href="/keyword/throws-exception/" >throws exception</a> { ... } public EXP visit(Relop n) <a href="/keyword/throws-exception/" >throws exception</a> { ... translate into value representation, return an ESEQ node } public EXP visit(Not n) <a href="/keyword/throws-exception/" >throws exception</a> { ... with value representation, 'not e' becomes '1 - e' } public EXP visit(NewArray n) <a href="/keyword/throws-exception/" >throws exception</a> { ... implement according to the pseudo template } public EXP visit(ArrayElm n) <a href="/keyword/throws-exception/" >throws exception</a> { EXP array = n.array.accept(this); EXP idx = n.idx.accept(this); return new MEM(...); } public EXP visit(ArrayLen n) <a href="/keyword/throws-exception/" >throws exception</a> { return new MEM(...); } Jingke Li (Portland State University) CS322 Project 1 Hints 8 / 10 Implementation -- Expres...