package org.jruby.ir.dataflow.analyses;
import org.jruby.ir.IRClosure;
import org.jruby.ir.IREvalScript;
import org.jruby.ir.IRScope;
import org.jruby.ir.Operation;
import org.jruby.ir.dataflow.FlowGraphNode;
import org.jruby.ir.instructions.*;
import org.jruby.ir.operands.*;
import org.jruby.ir.representations.BasicBlock;
import org.jruby.ir.util.Edge;
import java.util.*;
public class LoadLocalVarPlacementNode extends FlowGraphNode<LoadLocalVarPlacementProblem, LoadLocalVarPlacementNode> {
public LoadLocalVarPlacementNode(LoadLocalVarPlacementProblem prob, BasicBlock n) {
super(prob, n);
}
@Override
public void init() {
inRequiredLoads = new HashSet<LocalVariable>();
outRequiredLoads = new HashSet<LocalVariable>();
}
@Override
public void buildDataFlowVars(Instr i) {
// Nothing to do -- because we are going to simply use non-closure, non-self, non-block LocalVariables as our data flow variables
// rather than build a new data flow type for it
}
@Override
public void applyPreMeetHandler() {
if (basicBlock.isExitBB()) inRequiredLoads = problem.getLoadsOnScopeExit();
}
@Override
public void compute_MEET(Edge e, LoadLocalVarPlacementNode pred) {
inRequiredLoads.addAll(pred.outRequiredLoads);
}
@Override
public void initSolution() {
reqdLoads = new HashSet<LocalVariable>(inRequiredLoads);
}
@Override
public void applyTransferFunction(Instr i) {
IRScope scope = problem.getScope();
boolean scopeBindingHasEscaped = scope.bindingHasEscaped();
// Right away, clear the variable defined by this instruction -- it doesn't have to be loaded!
if (i instanceof ResultInstr) {
reqdLoads.remove(((ResultInstr) i).getResult());
}
// Process closure accepting instrs specially -- these are the sites of binding loads!
if (i instanceof ClosureAcceptingInstr) {
Operand o = ((ClosureAcceptingInstr)i).getClosureArg();
if (o != null && o instanceof WrappedIRClosure) {
IRClosure cl = ((WrappedIRClosure) o).getClosure();
// Variables defined in the closure do not need to be loaded anymore at
// program points before the call, because they will be loaded after the
// call completes to fetch the latest value.
//
// Allocate a new hash-set and modify it to get around ConcurrentModificationException on reqdLoads
Set<LocalVariable> newReqdLoads = new HashSet<LocalVariable>(reqdLoads);
for (LocalVariable v: reqdLoads) {
if (cl.definesLocalVariable(v)) newReqdLoads.remove(v);
}
reqdLoads = newReqdLoads;
}
// In this case, we are going to blindly load everything -- so, at the call site, pending loads dont carry over!
if (scopeBindingHasEscaped) {
reqdLoads.clear();
} else {
// All variables not defined in the current scope have to be always loaded
// because of multi-threading scenarios where some other scope
// could update this variable concurrently.
//
// Allocate a new hash-set and modify it to get around ConcurrentModificationException on reqdLoads
Set<LocalVariable> newReqdLoads = new HashSet<LocalVariable>(reqdLoads);
for (LocalVariable v: reqdLoads) {
if (!scope.definesLocalVariable(v)) newReqdLoads.remove(v);
}
reqdLoads = newReqdLoads;
}
} else if (scopeBindingHasEscaped && (i.getOperation() == Operation.PUT_GLOBAL_VAR)) {
// global-var tracing can execute closures set up in previous trace-var calls
// in which case we would have the 'scopeBindingHasEscaped' flag set to true
reqdLoads.clear();
}
if (i.getOperation() == Operation.BINDING_STORE) {
LocalVariable lv = ((StoreLocalVarInstr)i).getLocalVar();
if (!lv.isSelf()) reqdLoads.add(lv);
} else {
// The variables used as arguments will need to be loaded
// %self is local to every scope and never crosses scope boundaries and need not be spilled/refilled
for (Variable x : i.getUsedVariables()) {
if (x instanceof LocalVariable && !x.isSelf()) {
reqdLoads.add((LocalVariable)x);
}
}
}
}
@Override
public boolean solutionChanged() {
// At the beginning of the scope and rescue block entries, required loads can be discarded
// since all these loads will be executed there.
if (basicBlock.isEntryBB() || basicBlock.isRescueEntry()) reqdLoads.clear();
//System.out.println("\n For CFG " + getCFG() + " BB " + _bb.getID());
//System.out.println("\t--> IN reqd loads : " + java.util.Arrays.toString(_inReqdLoads.toArray()));
//System.out.println("\t--> OUT reqd loads : " + java.util.Arrays.toString(_outReqdLoads.toArray()));
return !outRequiredLoads.equals(reqdLoads);
}
@Override
public void finalizeSolution() {
outRequiredLoads = reqdLoads;
}
@Override
public String toString() {
return "";
}
private TemporaryLocalVariable getLocalVarReplacement(LocalVariable v, IRScope scope, Map<Operand, Operand> varRenameMap) {
TemporaryLocalVariable value = (TemporaryLocalVariable)varRenameMap.get(v);
if (value == null) {
value = scope.getNewTemporaryVariableFor(v);
varRenameMap.put(v, value);
}
return value;
}
public void addLoads(Map<Operand, Operand> varRenameMap) {
IRScope scope = problem.getScope();
boolean isEvalScript = scope instanceof IREvalScript;
boolean scopeBindingHasEscaped = scope.bindingHasEscaped();
List<Instr> instrs = basicBlock.getInstrs();
ListIterator<Instr> it = instrs.listIterator(instrs.size());
initSolution();
while (it.hasPrevious()) {
Instr i = it.previous();
// Right away, clear the variable defined by this instruction -- it doesn't have to be loaded!
if (i instanceof ResultInstr) reqdLoads.remove(((ResultInstr) i).getResult());
// Process closure accepting instrs specially -- these are the sites of binding loads!
if (i instanceof ClosureAcceptingInstr) {
Operand o = ((ClosureAcceptingInstr)i).getClosureArg();
if (o != null && o instanceof WrappedIRClosure) {
IRClosure cl = ((WrappedIRClosure) o).getClosure();
// Only those variables that are defined in the closure, and are in the required loads set
// will need to be loaded from the binding after the call! Rest can wait ..
it.next();
for (Iterator<LocalVariable> iter = reqdLoads.iterator(); iter.hasNext();) {
LocalVariable v = iter.next();
if (cl.definesLocalVariable(v)) {
it.add(new LoadLocalVarInstr(scope, getLocalVarReplacement(v, scope, varRenameMap), v));
it.previous();
iter.remove();
}
}
it.previous();
}
// In this case, we are going to blindly load everything
if (scopeBindingHasEscaped) {
it.next();
for (LocalVariable v: reqdLoads) {
it.add(new LoadLocalVarInstr(scope, getLocalVarReplacement(v, scope, varRenameMap), v));
it.previous();
}
it.previous();
reqdLoads.clear();
} else {
// All variables not defined in the current scope have to be always loaded
// because of multi-threading scenarios where some other scope
// could update this variable concurrently.
it.next();
for (Iterator<LocalVariable> iter = reqdLoads.iterator(); iter.hasNext();) {
LocalVariable v = iter.next();
if (!scope.definesLocalVariable(v)) {
it.add(new LoadLocalVarInstr(scope, getLocalVarReplacement(v, scope, varRenameMap), v));
it.previous();
iter.remove();
}
}
it.previous();
}
} else if (scopeBindingHasEscaped && (i.getOperation() == Operation.PUT_GLOBAL_VAR)) {
// global-var tracing can execute closures set up in previous trace-var calls
// in which case we would have the 'scopeBindingHasEscaped' flag set to true
it.next();
for (LocalVariable v : reqdLoads) {
it.add(new LoadLocalVarInstr(scope, getLocalVarReplacement(v, scope, varRenameMap), v));
it.previous();
}
it.previous();
reqdLoads.clear();
}
if (i.getOperation() == Operation.BINDING_STORE) {
LocalVariable lv = ((StoreLocalVarInstr)i).getLocalVar();
if (!lv.isSelf()) {
reqdLoads.add(lv);
// SSS FIXME: Why is this reqd again? Document with example
// Make sure there is a replacement var for all local vars
getLocalVarReplacement(lv, scope, varRenameMap);
}
} else {
// The variables used as arguments will need to be loaded
// %self is local to every scope and never crosses scope boundaries and need not be spilled/refilled
for (Variable v : i.getUsedVariables()) {
if (!(v instanceof LocalVariable)) continue;
LocalVariable lv = (LocalVariable)v;
if (!lv.isSelf()) {
reqdLoads.add(lv);
// SSS FIXME: Why is this reqd again? Document with example
// Make sure there is a replacement var for all local vars
getLocalVarReplacement(lv, scope, varRenameMap);
}
}
}
}
// Add loads on entry of a rescue block.
if (basicBlock.isRescueEntry()) {
for (LocalVariable v : reqdLoads) {
it.add(new LoadLocalVarInstr(scope, getLocalVarReplacement(v, scope, varRenameMap), v));
}
}
// Load first use of variables in closures
if (scope instanceof IRClosure && basicBlock.isEntryBB()) {
// System.out.println("\n[In Entry BB] For CFG " + getCFG() + ":");
// System.out.println("\t--> Reqd loads : " + java.util.Arrays.toString(reqdLoads.toArray()));
for (LocalVariable v : reqdLoads) {
if (scope.usesLocalVariable(v) || scope.definesLocalVariable(v)) {
if (isEvalScript || !(v instanceof ClosureLocalVariable) || (scope != ((ClosureLocalVariable)v).definingScope)) {
it.add(new LoadLocalVarInstr(scope, getLocalVarReplacement(v, scope, varRenameMap), v));
}
}
}
}
}
Set<LocalVariable> inRequiredLoads; // On entry to flow graph node: Variables that need to be loaded from the heap binding
Set<LocalVariable> outRequiredLoads; // On exit from flow graph node: Variables that need to be loaded from the heap binding
Set<LocalVariable> reqdLoads; // Temporary state while applying transfer function
}