Building a control-flow graph from an AST with a visitor pattern using Java
- by omegatai
Hi guys,
I'm trying to figure out how to implement my LEParserCfgVisitor class as to build a control-flow graph from an Abstract-Syntax-Tree already generated with JavaCC. I know there are tools that already exist, but I'm trying to do it in preparation for my Compilers final.
I know I need to have a data structure that keeps the graph in memory, and I want to be able to keep attributes like IN, OUT, GEN, KILL in each node as to be able to do a control-flow analysis later on.
My main problem is that I haven't figured out how to connect the different blocks together, as to have the right edge between each blocks depending on their nature: branch, loops, etc. In other words, I haven't found an explicit algorithm that could help me build my visitor.
Here is my empty Visitor. You can see it works on basic langage expressions, like if, while and basic operations (+,-,x,^,...)
public class LEParserCfgVisitor implements LEParserVisitor
{
public Object visit(SimpleNode node, Object data) { return data; }
public Object visit(ASTProgram node, Object data) {
data = node.childrenAccept(this, data);
return data;
}
public Object visit(ASTBlock node, Object data) {
}
public Object visit(ASTStmt node, Object data) {
}
public Object visit(ASTAssignStmt node, Object data) {
}
public Object visit(ASTIOStmt node, Object data) {
}
public Object visit(ASTIfStmt node, Object data) {
}
public Object visit(ASTWhileStmt node, Object data) {
}
public Object visit(ASTExpr node, Object data) {
}
public Object visit(ASTAddExpr node, Object data) {
}
public Object visit(ASTFactExpr node, Object data) {
}
public Object visit(ASTMultExpr node, Object data) {
}
public Object visit(ASTPowerExpr node, Object data) {
}
public Object visit(ASTUnaryExpr node, Object data) {
}
public Object visit(ASTBasicExpr node, Object data) {
}
public Object visit(ASTFctExpr node, Object data) {
}
public Object visit(ASTRealValue node, Object data) {
}
public Object visit(ASTIntValue node, Object data) {
}
public Object visit(ASTIdentifier node, Object data) {
}
}
Can anyone give me a hand?
Thanks!
