Análise estática de Código

src/DeadCode.rsc

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+module DeadCode
+import lang::java::\syntax::Java18;
+import ParseTree; 
+import IO;
+import Set; 
+
+/*
+Deteccao e remocao de atribuicoes que não usadas.
+Base: Live variables do livro Principles of Progam Analysis
+
+*/
+
+bool checkExpUse(Identifier left, CompilationUnit unit) {
+  bool res = false;
+  top-down-break visit(unit) {
+    case (Assignment)`<LeftHandSide dst> <AssignmentOperator op> <Identifier y>`: { 
+    	res = (left == y);
+    }
+
+    case (Assignment)`<LeftHandSide dst> <AssignmentOperator op> <MethodInvocation m>`:{
+    	res = checkMethodArgs(m, left);
+    }
+  }
+  return res; 
+}
+
+bool checkMethodArgs(MethodInvocation m, Identifier left){
+	bool res = false;
+	top-down-break visit(m){
+		case (MethodInvocation)`<MethodName mName>(<Identifier arg>)`: {
+			res = (arg == left);
+		}
+	}
+	return res;
+}
+
+
+CompilationUnit removeDeadAssignment(CompilationUnit unit) =  visit(unit){
+
+    case (Assignment) `<Identifier leftId> <AssignmentOperator s> <Expression rightExp>`  => 
+    (Assignment) `<Identifier leftId> <AssignmentOperator s> eliminado` when !checkExpUse(leftId, unit)
+
+    case (PostfixExpression) `<Identifier pExp>`  => 
+    (PostfixExpression) `eliminado` when !checkExpUse(pExp, unit)
+
+};
+

testes/DeadCodeExamples.java

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+class DeadCodeExamples {
+	int teste(int var)
+	{
+		return var;
+	}
+
+	void casos()
+	{
+		int x,y,z;
+
+		//Teste 1 - eliminando atribuicoes
+		/*
+		y = 4;
+		x = 2;
+		z = 4;
+		*/
+
+		//Teste 2 - preservando alguma coisa
+		/*
+		y = 4;
+		x = 2;
+		z = y;
+		*/
+
+		//Teste 3 - variavel usada como parametro
+		/*
+		y = 4;
+		x = 2;
+		z = teste(y);
+		*/
+
+		//Teste 4 - PostfixExpression
+
+		y = 4;
+		x = 2;
+		z = y;
+		y++;
+		x++;
+
+	}
+}