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3494 lines (2997 loc) · 121 KB
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// Copyright (c) Microsoft Corporation. All rights reserved.
// 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];