PSScriptAnalyzer/Engine/VariableAnalysisBase.cs at main · PowerShell/PSScriptAnalyzer · GitHub

History

3494 lines (2997 loc) · 121 KB

Raw

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

583

584

585

586

587

588

589

590

591

592

593

594

595

596

597

598

599

600

601

602

603

604

605

606

607

608

609

610

611

612

613

614

615

616

617

618

619

620

621

622

623

624

625

626

627

628

629

630

631

632

633

634

635

636

637

638

639

640

641

642

643

644

645

646

647

648

649

650

651

652

653

654

655

656

657

658

659

660

661

662

663

664

665

666

667

668

669

670

671

672

673

674

675

676

677

678

679

680

681

682

683

684

685

686

687

688

689

690

691

692

693

694

695

696

697

698

699

700

701

702

703

704

705

706

707

708

709

710

711

712

713

714

715

716

717

718

719

720

721

722

723

724

725

726

727

728

729

730

731

732

733

734

735

736

737

738

739

740

741

742

743

744

745

746

747

748

749

750

751

752

753

754

755

756

757

758

759

760

761

762

763

764

765

766

767

768

769

770

771

772

773

774

775

776

777

778

779

780

781

782

783

784

785

786

787

788

789

790

791

792

793

794

795

796

797

798

799

800

801

802

803

804

805

806

807

808

809

810

811

812

813

814

815

816

817

818

819

820

821

822

823

824

825

826

827

828

829

830

831

832

833

834

835

836

837

838

839

840

841

842

843

844

845

846

847

848

849

850

851

852

853

854

855

856

857

858

859

860

861

862

863

864

865

866

867

868

869

870

871

872

873

874

875

876

877

878

879

880

881

882

883

884

885

886

887

888

889

890

891

892

893

894

895

896

897

898

899

900

901

902

903

904

905

906

907

908

909

910

911

912

913

914

915

916

917

918

919

920

921

922

923

924

925

926

927

928

929

930

931

932

933

934

935

936

937

938

939

940

941

942

943

944

945

946

947

948

949

950

951

952

953

954

955

956

957

958

959

960

961

962

963

964

965

966

967

968

969

970

971

972

973

974

975

976

977

978

979

980

981

982

983

984

985

986

987

988

989

990

991

992

993

994

995

996

997

998

999

1000

// Licensed under the MIT License.

using System;

using System.Collections;

using System.Collections.Generic;

using System.Collections.ObjectModel;

using System.Globalization;

using System.Linq;

using System.Management.Automation;

using System.Management.Automation.Language;

using System.Reflection;

namespace Microsoft.Windows.PowerShell.ScriptAnalyzer

{

/// <summary>

/// Base class for variable details

/// </summary>

public class VariableDetails

{

/// <summary>

/// Type of variable

/// </summary>

public Type Type = typeof(Unreached);

/// <summary>

/// Name of variable (can be set by ssa)

/// </summary>

public string Name;

/// <summary>

/// Real name of variable

/// </summary>

public string RealName;

/// <summary>

/// Value of variable

/// </summary>

public object Constant = Unreached.UnreachedConstant;

/// <summary>

/// Block that variable is initialized in

/// </summary>

public Block DefinedBlock;

/// <summary>

/// Returns true if the two variable details have the same constant and same type

/// </summary>

/// <param name="varDetailsA"></param>

/// <param name="varDetailsB"></param>

/// <returns></returns>

public static bool SameConstantAndType(VariableDetails varDetailsA, VariableDetails varDetailsB)

{

if (varDetailsA == null)

{

if (varDetailsB != null)

{

return false;

}

return true;

}

return ((varDetailsA.Constant == null && varDetailsB.Constant == null)

|| (varDetailsA.Constant != null && varDetailsA.Constant.Equals(varDetailsB.Constant)))

&& varDetailsA.Type == varDetailsB.Type;

}

/// <summary>

/// Class that stores the details of variable analysis

/// </summary>

public class VariableAnalysisDetails : VariableDetails

{

internal VariableAnalysisDetails()

{

this.AssociatedAsts = new List<Ast>();

}

/// <summary>

/// The Asts associated with the variables

/// </summary>

public List<Ast> AssociatedAsts { get; internal set; }

internal List<Block> AssignedBlocks = new List<Block>();

}

/// <summary>

/// This class is used to find all the variables in an ast

/// </summary>

public class FindAllVariablesVisitor : AstVisitor

{

/// <summary>

/// Visit an Ast and gets details about all the variables

/// </summary>

/// <param name="ast"></param>

/// <returns></returns>

public static Dictionary<string, VariableAnalysisDetails> Visit(Ast ast)

{

if (!(ast is ScriptBlockAst || ast is FunctionMemberAst || ast is FunctionDefinitionAst))

{

return null;

}

var visitor = new FindAllVariablesVisitor();

visitor.InitializeVariables(ast);

// Visit the body before the parameters so we don't allocate any tuple slots for parameters

// if we won't be optimizing because of a call to new-variable/remove-variable, etc.

if (ast is ScriptBlockAst)

{

(ast as ScriptBlockAst).Visit(visitor);

}

else if (ast is FunctionMemberAst)

{

(ast as FunctionMemberAst).Body.Visit(visitor);

}

else if (ast is FunctionDefinitionAst)

{

(ast as FunctionDefinitionAst).Body.Visit(visitor);

}

if (ast is FunctionMemberAst && (ast as FunctionMemberAst).Parameters != null)

{

visitor.VisitParameters((ast as FunctionMemberAst).Parameters);

}

else if (ast is FunctionDefinitionAst && (ast as FunctionDefinitionAst).Parameters != null)

{

visitor.VisitParameters((ast as FunctionDefinitionAst).Parameters);

}

return visitor._variables;

}

internal readonly Dictionary<string, VariableAnalysisDetails> _variables

= new Dictionary<string, VariableAnalysisDetails>(StringComparer.OrdinalIgnoreCase);

internal void InitializeVariables(Ast ast)

{

_variables.Add("true", new VariableAnalysisDetails { Name = "true", RealName = "true", Type = typeof(bool) });

_variables.Add("false", new VariableAnalysisDetails { Name = "false", RealName = "true", Type = typeof(bool) });

if (ast is FunctionMemberAst)

{

TypeDefinitionAst psClass = AssignmentTarget.FindClassAncestor(ast);

if (psClass != null)

{

_variables.Add("this", new VariableAnalysisDetails { Name = "this", RealName = "this", Constant = SpecialVars.ThisVariable });

}

internal void VisitParameters(ReadOnlyCollection<ParameterAst> parameters)

{

foreach (ParameterAst t in parameters)

{

var variableExpressionAst = t.Name;

var varPath = variableExpressionAst.VariablePath;

var variableName = AssignmentTarget.GetUnaliasedVariableName(varPath);

VariableAnalysisDetails analysisDetails;

if (_variables.TryGetValue(variableName, out analysisDetails))

{

// Forget whatever type we deduced in the body, we'll revisit that type after walking

// the flow graph. We should see the parameter type for the variable first.

analysisDetails.Type = t.StaticType;

}

else

{

NoteVariable(variableName, t.StaticType);

}

/// <summary>

/// Visit datastatement

/// </summary>

/// <param name="dataStatementAst"></param>

/// <returns></returns>

public override AstVisitAction VisitDataStatement(DataStatementAst dataStatementAst)

{

if (dataStatementAst != null && dataStatementAst.Variable != null)

{

NoteVariable(dataStatementAst.Variable, null);

}

return AstVisitAction.Continue;

}

/// <summary>

/// Visit SwitchStatement

/// </summary>

/// <param name="switchStatementAst"></param>

/// <returns></returns>

public override AstVisitAction VisitSwitchStatement(SwitchStatementAst switchStatementAst)

{

NoteVariable(SpecialVars.@switch, typeof(IEnumerator));

return AstVisitAction.Continue;

}

/// <summary>

/// Visit Foreach statement

/// </summary>

/// <param name="forEachStatementAst"></param>

/// <returns></returns>

public override AstVisitAction VisitForEachStatement(ForEachStatementAst forEachStatementAst)

{

NoteVariable(SpecialVars.@foreach, typeof(IEnumerator));

return AstVisitAction.Continue;

}

/// <summary>

/// Visit VariableExpression

/// </summary>

/// <param name="variableExpressionAst"></param>

/// <returns></returns>

public override AstVisitAction VisitVariableExpression(VariableExpressionAst variableExpressionAst)

{

if (variableExpressionAst == null)

{

return AstVisitAction.Continue;

}

NoteVariable(AssignmentTarget.GetUnaliasedVariableName(variableExpressionAst.VariablePath), null);

return AstVisitAction.Continue;

}

/// <summary>

/// Visit UsingExpression

/// </summary>

/// <param name="usingExpressionAst"></param>

/// <returns></returns>

public override AstVisitAction VisitUsingExpression(UsingExpressionAst usingExpressionAst)

{

// On the local machine, we may have set the index because of a call to ScriptBlockToPowerShell or Invoke-Command.

// On the remote machine, the index probably isn't set yet, so we set it here, mostly to avoid another pass

// over the ast. We assert below to ensure we're setting to the same value in both the local and remote cases.

// Cannot access the RuntimeUsingIndex

//if (usingExpressionAst.RuntimeUsingIndex == -1)

//{

// usingExpressionAst.RuntimeUsingIndex = _runtimeUsingIndex;

//}

//System.Diagnostics.Debug.Assert(usingExpressionAst.RuntimeUsingIndex == _runtimeUsingIndex, "Logic error in visiting using expressions.");

return AstVisitAction.Continue;

}

/// <summary>

/// Visit Command

/// </summary>

/// <param name="commandAst"></param>

/// <returns></returns>

public override AstVisitAction VisitCommand(CommandAst commandAst)

{

return AstVisitAction.Continue;

}

/// <summary>

/// Visit Function

/// </summary>

/// <param name="functionDefinitionAst"></param>

/// <returns></returns>

public override AstVisitAction VisitFunctionDefinition(FunctionDefinitionAst functionDefinitionAst)

{

// We don't want to discover any variables in nested functions - they get their own scope.

return AstVisitAction.SkipChildren;

}

/// <summary>

/// Visit ScriptBlock

/// </summary>

/// <param name="scriptBlockExpressionAst"></param>

/// <returns></returns>

public override AstVisitAction VisitScriptBlockExpression(ScriptBlockExpressionAst scriptBlockExpressionAst)

{

// We don't want to discover any variables in script block expressions - they get their own scope.

return AstVisitAction.Continue;

}

/// <summary>

/// Visit Trap

/// </summary>

/// <param name="trapStatementAst"></param>

/// <returns></returns>

public override AstVisitAction VisitTrap(TrapStatementAst trapStatementAst)

{

// We don't want to discover any variables in traps - they get their own scope.

return AstVisitAction.SkipChildren;

}

// Return true if the variable is newly allocated and should be allocated in the locals tuple.

internal void NoteVariable(string variableName, Type type)

{

if (!_variables.ContainsKey(variableName))

{

var details = new VariableAnalysisDetails

{

Name = variableName,

Type = type

};

_variables.Add(variableName, details);

}

class LoopGotoTargets

{

internal LoopGotoTargets(string label, Block breakTarget, Block continueTarget)

{

this.Label = label;

this.BreakTarget = breakTarget;

this.ContinueTarget = continueTarget;

}

internal string Label { get; private set; }

internal Block BreakTarget { get; private set; }

internal Block ContinueTarget { get; private set; }

}

/// <summary>

/// Represents unreached variable

/// </summary>

public class Unreached

{

internal static object UnreachedConstant = new object();

}

/// <summary>

/// Represent undetermined variable

/// </summary>

public class Undetermined

{

internal static object UndeterminedConstant = new object();

}

/// <summary>

/// Class that represents a Phi function

/// </summary>

public class Phi : VariableDetails

{

internal VariableTarget[] Operands;

/// <summary>

/// Constructor

/// </summary>

/// <param name="VarName"></param>

/// <param name="block"></param>

internal Phi(String VarName, Block block)

{

Name = VarName;

Operands = new VariableTarget[block._predecessors.Count()];

for (int i = 0; i < Operands.Length; i += 1)

{

Operands[i] = new VariableTarget();

}

RealName = Name;

DefinedBlock = block;

}

/// <summary>

/// A block in the data flow graph

/// </summary>

public class Block

{

/// <summary>

/// Asts in the block

/// </summary>

public LinkedList<object> _asts = new LinkedList<object>();

internal readonly List<Block> _successors = new List<Block>();

/// <summary>

/// Predecessor blocks

/// </summary>

public List<Block> _predecessors = new List<Block>();

internal readonly HashSet<Block> SSASuccessors = new HashSet<Block>();

internal List<Block> DominatorSuccessors = new List<Block>();

internal static int count;

internal int PostOrder;

internal HashSet<Block> dominanceFrontierSet = new HashSet<Block>();

internal List<Phi> Phis = new List<Phi>();

private static Dictionary<string, Stack<VariableAnalysisDetails>> SSADictionary = new Dictionary<string, Stack<VariableAnalysisDetails>>(StringComparer.OrdinalIgnoreCase);

internal static Dictionary<string, VariableAnalysisDetails> VariablesDictionary;

internal static Dictionary<string, VariableAnalysisDetails> InternalVariablesDictionary = new Dictionary<string, VariableAnalysisDetails>(StringComparer.OrdinalIgnoreCase);

private static Dictionary<string, int> Counters = new Dictionary<string, int>();

internal object _visitData;

internal bool _visited;

internal bool _throws;

internal bool _returns;

internal bool _unreachable;

// Only Entry block, that can be constructed via NewEntryBlock() is reachable initially.

// all other blocks are unreachable.

// reachability of block should be proved with FlowsTo() calls.

public Block()

{

this._unreachable = true;

}

public static Block NewEntryBlock()

{

return new Block(unreachable: false);

}

private Block(bool unreachable)

{

this._unreachable = unreachable;

}

/// <summary>

/// Tell flow analysis that this block can flow to next block.

/// </summary>

/// <param name="next"></param>

internal void FlowsTo(Block next)

{

if (_successors.IndexOf(next) < 0)

{

if (!_unreachable)

{

next._unreachable = false;

}

_successors.Add(next);

next._predecessors.Add(this);

}

internal void AddAst(object ast)

{

_asts.AddLast(ast);

}

internal void AddFirstAst(object ast)

{

_asts.AddFirst(ast);

}

/// <summary>

/// Insert phi nodes at dominance frontier of each set.

/// </summary>

/// <param name="Variables"></param>

internal static void InsertPhiNodes(Dictionary<string, VariableAnalysisDetails> Variables)

{

foreach (var variable in Variables.Keys.ToList())

{

List<Block> everOnWorkList = new List<Block>();

List<Block> workList = new List<Block>();

List<Block> hasPhiAlready = new List<Block>();

everOnWorkList.AddRange(Variables[variable].AssignedBlocks);

workList.AddRange(Variables[variable].AssignedBlocks);

while (workList.Count != 0)

{

Block block = workList[workList.Count - 1];

workList.RemoveAt(workList.Count - 1);

foreach (Block frontier in block.dominanceFrontierSet)

{

if (!hasPhiAlready.Contains(frontier))

{

// INSERT PHI FUNCTION

frontier.Phis.Add(new Phi(variable, frontier));

hasPhiAlready.Add(frontier);

}

if (!everOnWorkList.Contains(frontier))

{

workList.Add(frontier);

everOnWorkList.Add(frontier);

}

/// <summary>

/// Fill in the DominanceFrontiersSet of each block.

/// </summary>

/// <param name="Blocks"></param>

/// <param name="Entry"></param>

internal static void DominanceFrontiers(List<Block> Blocks, Block Entry)

{

Block[] dominators = SetDominators(Entry, Blocks);

foreach (Block block in Blocks)

{

if (block._predecessors.Count >= 2)

{

foreach (Block pred in block._predecessors)

{

Block runner = pred;

while (runner != dominators[block.PostOrder])

{

runner.dominanceFrontierSet.Add(block);

runner = dominators[block.PostOrder];

}

/// <summary>

/// Returns the immediate dominator of each block. The array returned is

/// indexed by postorder number of each block.

/// Based on https://www.cs.rice.edu/~keith/Embed/dom.pdf

/// </summary>

/// <param name="entry"></param>

/// <param name="Blocks"></param>

/// <returns></returns>

internal static Block[] SetDominators(Block entry, List<Block> Blocks)

{

Block[] dominators = new Block[Blocks.Count];

foreach (var block in Blocks)

{

dominators[block.PostOrder] = null;

}

dominators[entry.PostOrder] = entry;

bool updated = true;

while (updated)

{

updated = false;

foreach (var block in Blocks)

{

if (block == entry)

{

continue;

}

if (block._predecessors.Count == 0)

{

continue;

}

Block dom = block._predecessors[0];

// Get first processed node

foreach (var pred in block._predecessors)

{

if (dominators[pred.PostOrder] != null)

{

dom = pred;

break;

}

Block firstSelected = dom;

foreach (var pred in block._predecessors)

{

if (firstSelected != pred && dominators[pred.PostOrder] != null)

{

// The order is reversed so we have to subtract from total

dom = Blocks[Blocks.Count - Intersect(pred, dom, dominators) - 1];

}

if (dominators[block.PostOrder] != dom)

{

dominators[block.PostOrder] = dom;

updated = true;

}

// Construct dominator tree

foreach (var block in Blocks)

{

dominators[block.PostOrder].DominatorSuccessors.Add(block);

}

return dominators;

}

/// <summary>

/// Given two nodes, return the postorder number of the closest node

/// that dominates both.

/// </summary>

/// <param name="block1"></param>

/// <param name="block2"></param>

/// <param name="Dominators"></param>

/// <returns></returns>

internal static int Intersect(Block block1, Block block2, Block[] Dominators)

{

int b1 = block1.PostOrder;

int b2 = block2.PostOrder;

while (b1 != b2)

{

while (b1 < b2)

{

b1 = Dominators[b1].PostOrder;

}

while (b2 < b1)

{

b2 = Dominators[b2].PostOrder;

}

return b1;

}

/// <summary>

/// Generate new name for each assignment using the counters.

/// </summary>

/// <param name="VarName"></param>

/// <param name="DefinedBlock"></param>

/// <returns></returns>

internal static string GenerateNewName(string VarName, Block DefinedBlock)

{

int i = Counters[VarName];

Counters[VarName] += 1;

string newName = String.Format(CultureInfo.CurrentCulture, "{0}{1}", VarName, i);

var varAnalysis = new VariableAnalysisDetails { Name = newName, DefinedBlock = DefinedBlock, RealName = VarName };

SSADictionary[VarName].Push(varAnalysis);

InternalVariablesDictionary[newName] = varAnalysis;

return newName;

}

/// <summary>

/// Rename each variable (each assignment will give variable a new name).

/// Also rename the phi function in each block as well

/// </summary>

/// <param name="block"></param>

internal static void RenameVariables(Block block)

{

if (block._visited)

{

return;

}

block._visited = true;

// foreach phi node generate new name

foreach (var phi in block.Phis)

{

phi.Name = GenerateNewName(phi.RealName, block);

}

foreach (object ast in block._asts)

{

AssignmentTarget assignTarget = ast as AssignmentTarget;

VariableTarget varTarget = null;

if (assignTarget != null && !String.IsNullOrEmpty(assignTarget.Name))

{

assignTarget.Name = GenerateNewName(assignTarget.Name, block);

varTarget = assignTarget._rightHandSideVariable;

}

varTarget = (varTarget != null) ? varTarget : ast as VariableTarget;

if (varTarget != null)

{

// If stack is empty then variable was not initialized;

if (SSADictionary[varTarget.RealName].Count == 0)

{

VariablesDictionary[VariableAnalysis.AnalysisDictionaryKey(varTarget.VarAst)] = new VariableAnalysisDetails { Name = varTarget.Name, DefinedBlock = null, Type = varTarget.Type, RealName = null };

}

else

{

VariableAnalysisDetails previous = SSADictionary[varTarget.RealName].Peek();

varTarget.Name = previous.Name;

if (previous.DefinedBlock != null)

{

previous.DefinedBlock.SSASuccessors.Add(block);

}

VariablesDictionary[VariableAnalysis.AnalysisDictionaryKey(varTarget.VarAst)] = previous;

}

foreach (var successor in block._successors)

{

int index = successor._predecessors.IndexOf(block);

foreach (var phi in successor.Phis)

{

// Stacks may be empty when variable was not initialized on all paths;

if (SSADictionary[phi.RealName].Count != 0)

{

VariableAnalysisDetails previous = SSADictionary[phi.RealName].Peek();

if (previous.DefinedBlock != null)

{

previous.DefinedBlock.SSASuccessors.Add(successor);

}

phi.Operands[index] = new VariableTarget(previous);

}

else

{

phi.Operands[index] = new VariableTarget();

phi.Operands[index].Name = GenerateNewName(phi.RealName, null);

}

// Preorder travel along the dominator tree

foreach (var successor in block.DominatorSuccessors)

{

RenameVariables(successor);

}

foreach (var phi in block.Phis)

{

SSADictionary[phi.RealName].Pop();

}

foreach (object ast in block._asts)

{

AssignmentTarget assignTarget = ast as AssignmentTarget;

if (assignTarget != null && !String.IsNullOrEmpty(assignTarget.RealName))

{

SSADictionary[assignTarget.RealName].Pop();

}

/// <summary>

/// Initialize SSA

/// </summary>

/// <param name="VariableAnalysis"></param>

/// <param name="Entry"></param>

/// <param name="Blocks"></param>

internal static void InitializeSSA(Dictionary<string, VariableAnalysisDetails> VariableAnalysis, Block Entry, List<Block> Blocks)

{

VariablesDictionary = new Dictionary<string, VariableAnalysisDetails>(StringComparer.OrdinalIgnoreCase);

foreach (var block in Blocks)

{

List<Block> _unreachables = new List<Block>();

foreach (var pred in block._predecessors)

{

if (pred._unreachable)

{

_unreachables.Add(pred);

pred._successors.Remove(block);

}

foreach (var pred in _unreachables)

{

block._predecessors.Remove(pred);

}

InternalVariablesDictionary.Clear();

SSADictionary.Clear();

Counters.Clear();

DominanceFrontiers(Blocks, Entry);

InsertPhiNodes(VariableAnalysis);

foreach (var key in VariableAnalysis.Keys.ToList())

{

SSADictionary[key] = new Stack<VariableAnalysisDetails>();

Counters[key] = 0;

}

RenameVariables(Entry);

}

/// <summary>

/// Sparse simple constant algorithm using use-def chain from SSA graph.

/// </summary>

/// <param name="Variables"></param>

/// <param name="Entry"></param>

/// <param name="Classes"></param>

/// <returns></returns>

internal static Tuple<Dictionary<string, VariableAnalysisDetails>, Dictionary<string, VariableAnalysisDetails>> SparseSimpleConstants(

Dictionary<string, VariableAnalysisDetails> Variables, Block Entry, List<TypeDefinitionAst> Classes)

{

List<Block> blocks = GenerateReverseDepthFirstOrder(Entry);

// Populate unreached variable with type from variables

foreach (var block in blocks)

{

foreach (var ast in block._asts)

{

VariableTarget varTarget = (ast is AssignmentTarget) ? (ast as AssignmentTarget)._rightHandSideVariable : (ast as VariableTarget);

if (varTarget != null && varTarget.Type == typeof(Unreached)

&& Variables.ContainsKey(varTarget.Name))

{

varTarget.Type = Variables[varTarget.Name].Type;

}

InitializeSSA(Variables, Entry, blocks);

LinkedList<Tuple<Block, Block>> workLists = new LinkedList<Tuple<Block, Block>>();

foreach (var block in blocks)

{

// Add a worklist from a block to itself to force analysis when variable is initialized but not used.

// This is useful in the case where the variable is used in the inner function

workLists.AddLast(Tuple.Create(block, block));

foreach (var ssaSucc in block.SSASuccessors)

{

if (ssaSucc != block)

{

workLists.AddLast(Tuple.Create(block, ssaSucc));

}

// Initialize variables in internal dictionary to undetermined

foreach (var key in InternalVariablesDictionary.Keys.ToList())

{

InternalVariablesDictionary[key].Constant = Undetermined.UndeterminedConstant;

InternalVariablesDictionary[key].Type = typeof(Undetermined);

}

// Initialize DefinedBlock of phi function. If it is null then that phi function is not initialized;

foreach (var block in blocks)

{

foreach (var phi in block.Phis)

{

foreach (var operand in phi.Operands)

{

phi.DefinedBlock = operand.DefinedBlock;

if (phi.DefinedBlock == null)

{

break;

}

InternalVariablesDictionary[phi.Name].DefinedBlock = phi.DefinedBlock;

}

while (workLists.Count != 0)

{

Tuple<Block, Block> SSAEdge = workLists.Last.Value;

workLists.RemoveLast();

Block start = SSAEdge.Item1;

Block end = SSAEdge.Item2;

HashSet<string> defVariables = new HashSet<string>();

foreach (var obj in start._asts)

{

var assigned = obj as AssignmentTarget;

if (assigned != null && assigned.Name != null && InternalVariablesDictionary.ContainsKey(assigned.Name))

{

VariableAnalysisDetails varAnalysis = InternalVariablesDictionary[assigned.Name];

// For cases where the type or constant of the rhs is initialized not through assignment.

if (assigned._rightHandSideVariable != null && !InternalVariablesDictionary.ContainsKey(assigned._rightHandSideVariable.Name)

&& Variables.ContainsKey(assigned._rightHandSideVariable.Name))

{

VariableAnalysisDetails rhsAnalysis = Variables[assigned._rightHandSideVariable.Name];

assigned.Type = rhsAnalysis.Type;

assigned.Constant = rhsAnalysis.Constant;

}

varAnalysis.Constant = assigned.Constant;

varAnalysis.Type = assigned.Type;

defVariables.Add(assigned.Name);

}

foreach (var phi in start.Phis)

{

EvaluatePhiConstant(phi);

EvaluatePhiType(phi);

defVariables.Add(phi.Name);

}

bool updated = false;

List<VariableTarget> varTargets = new List<VariableTarget>();

varTargets.AddRange(end._asts.Where(item => item is VariableTarget).Cast<VariableTarget>());

foreach (var phi in end.Phis)

{

varTargets.AddRange(phi.Operands);

}

foreach (var varTarget in varTargets)

{

if (defVariables.Contains(varTarget.Name))

{

var analysisDetails = InternalVariablesDictionary[varTarget.Name];

if (!VariableDetails.SameConstantAndType(varTarget, analysisDetails))

{

updated = true;

}

varTarget.Constant = analysisDetails.Constant;

varTarget.Type = analysisDetails.Type;

VariablesDictionary[VariableAnalysis.AnalysisDictionaryKey(varTarget.VarAst)] = InternalVariablesDictionary[varTarget.Name];

}

foreach (var ast in end._asts)

{

var assigned = ast as AssignmentTarget;

if (assigned != null && assigned.Name != null && assigned._leftHandSideVariable != null)

{

// Handle cases like $b = $a after we found out the value of $a

if (assigned._rightHandSideVariable != null

&& defVariables.Contains(assigned._rightHandSideVariable.Name))

{

// Ignore assignments like $a = $a

if (!String.Equals(assigned._rightHandSideVariable.Name, assigned.Name, StringComparison.OrdinalIgnoreCase))

{

if (!InternalVariablesDictionary.ContainsKey(assigned._rightHandSideVariable.Name))

{

continue;

}

var analysisDetails = InternalVariablesDictionary[assigned._rightHandSideVariable.Name];

if (!VariableDetails.SameConstantAndType(assigned, analysisDetails))

{

updated = true;

}

assigned.Constant = analysisDetails.Constant;

assigned.Type = analysisDetails.Type;

}

continue;

}

//TODO

// Handle cases like $b = $a.SomeMethod or $a.SomeType after we found out the value of $a

if (assigned._rightAst != null)

{

CommandExpressionAst cmeAst = assigned._rightAst as CommandExpressionAst;

MemberExpressionAst memAst = (cmeAst != null) ? (cmeAst.Expression as MemberExpressionAst) : null;

// Don't handle the this case because this is handled in assignment target

if (memAst != null && memAst.Expression is VariableExpressionAst)

{

VariableAnalysisDetails analysis = VariablesDictionary[VariableAnalysis.AnalysisDictionaryKey(memAst.Expression as VariableExpressionAst)];

TypeDefinitionAst psClass = Classes.FirstOrDefault(item => String.Equals(item.Name, analysis.Type?.FullName, StringComparison.OrdinalIgnoreCase));

Type possibleType = AssignmentTarget.GetTypeFromMemberExpressionAst(memAst, analysis, psClass);

if (possibleType != null && possibleType != assigned.Type)

{

assigned.Type = possibleType;

updated = true;

continue;

}

if (updated)

{

foreach (var block in end.SSASuccessors)

{

// Add to the front instead of the end since we are removing from end.

workLists.AddFirst(Tuple.Create(end, block));

}

return Tuple.Create(VariablesDictionary, InternalVariablesDictionary);

}

/// <summary>

/// Evaluate the constant value at a phi node

/// </summary>

/// <param name="phi"></param>

internal static void EvaluatePhiConstant(Phi phi)

{

int allUnreached = 0;

object constantSoFar = null;

bool first = true;

if (phi.Operands.Length == 0 || phi.DefinedBlock == null)

{

return;

}

foreach (var operand in phi.Operands)

{

var operandDetails = InternalVariablesDictionary[operand.Name];

View remainder of file in raw view

PSScriptAnalyzer/Engine/VariableAnalysisBase.cs at main · PowerShell/PSScriptAnalyzer · GitHub

Navigation Menu

Uh oh!

PSScriptAnalyzer/Engine/VariableAnalysisBase.cs at main · PowerShell/PSScriptAnalyzer · GitHub

Navigation Menu

Uh oh!

Expand file tree

Breadcrumbs

VariableAnalysisBase.cs

Latest commit

History

Breadcrumbs

VariableAnalysisBase.cs

File metadata and controls

Footer

Footer navigation