wala
No dominance frontier error when creating PDG including switch case only containing default branch in CAst
I'm getting the error
java.lang.IllegalArgumentException: no dominance frontier for node BB[SSA:13..13]12 - source_code_for_testing.dominance_frontier.PostgreSQLErrorConverter.convert(Ljava/sql/SQLException;)I
at com.ibm.wala.util.graph.dominators.DominanceFrontiers.getDominanceFrontier(DominanceFrontiers.java:48)
at com.ibm.wala.cfg.cdg.ControlDependenceGraph.buildControlDependence(ControlDependenceGraph.java:72)
at com.ibm.wala.cfg.cdg.ControlDependenceGraph.<init>(ControlDependenceGraph.java:220)
at com.ibm.wala.cfg.cdg.ControlDependenceGraph.<init>(ControlDependenceGraph.java:225)
at com.ibm.wala.ipa.slicer.PDG.createControlDependenceEdges(PDG.java:270)
at com.ibm.wala.ipa.slicer.PDG.createScalarEdges(PDG.java:200)
at com.ibm.wala.ipa.slicer.PDG.populate(PDG.java:193)
at com.ibm.wala.ipa.slicer.PDG.iterator(PDG.java:1216)
package source_code_for_testing.dominance_frontier;
import java.sql.SQLException;
import org.apache.log4j.Logger;
/**
* Converts SQLExceptions from PostgreSQL into SQLPower error numbers.
*/
public class PostgreSQLErrorConverter extends AbstractErrorConverter {
private final static Logger logger = Logger.getLogger(PostgreSQLErrorConverter.class);
public int convert(SQLException e) {
String state = e.getSQLState();
logger.debug("SQL STATE = " + state);
if ("28000".equals(state))
return INVALID_LOGON;
if ("42703".equals(state))
return UNKNOWN_COLUMN; // postgresql 8.x, proto version 3
switch (e.getErrorCode()) {
default:
return UNKNOWN_ERROR;
}
}
}
It looks like the basic block that's causing this error has no immediate dominators (the dominance info's dominator property is null). I've verified I don't encounter the error if I change
switch (e.getErrorCode()) {
default:
return UNKNOWN_ERROR;
}
to
return UNKNOWN_ERROR;
or
switch (e.getErrorCode()) {
case 1:
return 1;
default:
return UNKNOWN_ERROR;
}
This is the simplest code snippet to where I can reproduce this locally
public class DominanceFrontierCase {
public int convert(Integer i) {
switch (i.intValue()) {
default:
return 1;
}
}
}
In AstTranslator, visitSwitch(CAstNode n, WalkContext c, CAstVisitor<WalkContext> visitor) calls to doSimpleSwitch(CAstNode n, WalkContext context, CAstVisitor<WalkContext> visitor) or doIfConvertSwitch(CAstNode n, WalkContext context, CAstVisitor<WalkContext> visitor) depending on the case. I see in doIfConvertSwitch that the defaultGotoBlock has fallthrough set to true; however, in doSimpleSwitch, the equivalent block seems to be set to false. When I change the latter to true, the error disappears
