public void attachLivenessInfo(FlowGraph flowGraph, FlowGraphDecorator flowGraphDecorator) {
for (Function function : flowGraph.getFunctions()) {
// Perform liveness analysis
TransferFunction<LiveVariableState> transferFunction = new LiveVariableTransferFunction();
BackwardAnalysis<LiveVariableState> analysis =
new BackwardAnalysis<LiveVariableState>(flowGraphDecorator, function);
Map<Node, LiveVariableState> states = analysis.solve(transferFunction);
// Attach live variables to each basic block
for (BasicBlock basicBlock : function.getBlocks()) {
LiveVariableState state =
transferFunction.join(flowGraphDecorator, states, basicBlock.getLastNode());
Set<Integer> liveVariables = state.getLiveVariables();
// NOTE: The EdgeTransfer function may use the conditional variable contained in an if node.
// We check if the last node of the basic block is an if node, and if it is, we add
// the conditional variable to the set of live variables.
if (basicBlock.getLastNode() instanceof IfNode) {
IfNode ifNode = (IfNode) basicBlock.getLastNode();
liveVariables.add(ifNode.getConditionVar());
}
int[] result = new int[liveVariables.size()];
Iterator<Integer> iterator = liveVariables.iterator();
int i = 0;
while (iterator.hasNext()) {
result[i] = iterator.next();
i++;
}
basicBlock.setLiveVariables(result);
}
}
}
/**
* Transfer for an exceptional-return statement.
*
* @param caller if non-null, only consider this caller
*/
public void transferExceptionalReturn(
BasicBlock block, State state, NodeAndContext<Context> caller, Context edge_context) {
Value v = state.readRegister(AbstractNode.EXCEPTION_REG);
state.removeRegister(AbstractNode.EXCEPTION_REG);
UserFunctionCalls.leaveUserFunction(
v, true, block.getFunction(), state, c, caller, edge_context);
}
/** Transfer ordinary and exceptional return for the given call node and callee entry. */
public void transferReturn(
AbstractNode call_node,
BasicBlock callee_entry,
Context caller_context,
Context callee_context,
Context edge_context) {
if (call_node instanceof BeginForInNode) {
for (EndForInNode endNode : ((BeginForInNode) call_node).getEndNodes()) {
BasicBlock end_block = endNode.getBlock();
if (c.getAnalysisLatticeElement().getState(end_block, callee_context)
!= null) // (EndForInNode uses same context as corresponding BeginForInNode)
c.addToWorklist(end_block, callee_context);
}
} else { // call_node is an ordinary call node
Function callee = callee_entry.getFunction();
BasicBlock ordinary_exit = callee.getOrdinaryExit();
BasicBlock exceptional_exit = callee.getExceptionalExit();
State ordinary_exit_state =
c.getAnalysisLatticeElement()
.getState(
ordinary_exit,
callee_context); // (ReturnNode uses same context as corresponding function entry
// node)
State exceptional_exit_state =
c.getAnalysisLatticeElement().getState(exceptional_exit, callee_context);
NodeAndContext<Context> caller = new NodeAndContext<>(call_node, caller_context);
if (ordinary_exit_state != null) {
if (ordinary_exit.getFirstNode() instanceof ReturnNode) {
ReturnNode returnNode = (ReturnNode) ordinary_exit.getFirstNode();
transferReturn(
returnNode.getReturnValueRegister(),
ordinary_exit,
ordinary_exit_state.clone(),
caller,
edge_context);
} else throw new AnalysisException("ReturnNode expected");
}
if (exceptional_exit_state != null) {
transferExceptionalReturn(
exceptional_exit, exceptional_exit_state.clone(), caller, edge_context);
}
}
}
/**
* Transfer for a return statement.
*
* @param caller if non-null, only consider this caller
*/
public void transferReturn(
int valueReg,
BasicBlock block,
State state,
NodeAndContext<Context> caller,
Context edge_context) {
Value v;
if (valueReg != AbstractNode.NO_VALUE) v = state.readRegister(valueReg);
else v = Value.makeUndef();
UserFunctionCalls.leaveUserFunction(
v, false, block.getFunction(), state, c, caller, edge_context);
}
/** Returns a string description of this entry. */
@Override
public String toString() {
return Integer.toString(b.getIndex());
}
/** Constructs a new entry. */
public Entry(BasicBlock b, CallContextType c) {
this.b = b;
this.c = c;
serial = next_serial++;
hash = b.getIndex() + c.hashCode();
}
