// For the first assignment to a local variable in a block before a control statement is hit,
// if the local variable is not mentioned previously, we turn this assignment into a local declaration.
private void AddDeclarationsWithInitialValues(IEnumerable<ILocalDefinition> localVariables, BasicBlock block)
{
List<ILocalDefinition> topLevelLocals = new List<ILocalDefinition>(localVariables);
List<ILocalDefinition> localsMet = new List<ILocalDefinition>();
for (int i = 0; i < block.Statements.Count; i++) {
if (topLevelLocals.Count == 0) break;
IExpressionStatement expressionStatement = block.Statements[i] as IExpressionStatement;
if (expressionStatement != null) {
IAssignment assignment = expressionStatement.Expression as IAssignment;
if (assignment != null) {
ILocalDefinition localDef = assignment.Target.Definition as ILocalDefinition;
if (localDef != null && topLevelLocals.Contains(localDef) && !localsMet.Contains(localDef) && !this.declaredLocals.ContainsKey(localDef)) {
LocalDeclarationStatement localDecl = new LocalDeclarationStatement() {
LocalVariable = localDef, InitialValue = assignment.Source, Locations = new List<ILocation>(expressionStatement.Locations),
};
this.declaredLocals.Add(localDef, true);
block.Statements[i] = localDecl;
topLevelLocals.Remove(localDef);
localsMet.Add(localDef);
}
}
}
LocalFinder finder = new LocalFinder();
finder.Traverse(block.Statements[i]);
foreach (ILocalDefinition local in finder.FoundLocals) {
if (!localsMet.Contains(local)) localsMet.Add(local);
}
//Once we see a statement that can transfer control somewhere else, we
//no longer know that any subsequent assignment dominates all references
//and hence cannot postpone adding the declaration until we can unify it with the assignment.
IGotoStatement gotoStatement = block.Statements[i] as IGotoStatement;
if (gotoStatement != null) break;
IConditionalStatement conditionalStatement = block.Statements[i] as IConditionalStatement;
if (conditionalStatement != null) break;
ISwitchStatement switchStatement = block.Statements[i] as ISwitchStatement;
if (switchStatement != null) break;
IForEachStatement foreachStatement = block.Statements[i] as IForEachStatement;
if (foreachStatement != null) break;
IForStatement forStatement = block.Statements[i] as IForStatement;
if (forStatement != null) break;
ITryCatchFinallyStatement tryStatement = block.Statements[i] as ITryCatchFinallyStatement;
if (tryStatement != null) break;
}
}
public static bool LocalOccursIn(IStatement s, ILocalDefinition local) {
Contract.Requires(s != null);
Contract.Requires(local != null);
var lf = new LocalFinder(local);
lf.Traverse(s);
return lf.found;
}