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public GenerateGet ( |
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| generator | The generator to output the CIL to. | |
| optimizationInfo | Information about any optimizations that should be performed. | |
| throwIfUnresolvable | bool | |
| 리턴 | void | |
public void GenerateGet(ILGenerator generator, OptimizationInfo optimizationInfo, bool throwIfUnresolvable)
{
// This method generates code to retrieve the value of a variable, given the name of
// variable and scope in which the variable is being referenced. The variable was
// not necessary declared in this scope - it might be declared in any of the parent
// scopes (together called a scope chain). The general algorithm is to start at the
// head of the chain and search backwards until the variable is found. There are
// two types of scopes: declarative scopes and object scopes. Object scopes are hard -
// it cannot be known at compile time whether the variable exists or not so runtime
// checks have to be inserted. Declarative scopes are easier - variables have to be
// declared and cannot be deleted. There is one tricky bit: new variables can be
// introduced into a declarative scope at runtime by a non-strict eval() statement.
// Even worse, variables that were introduced by means of an eval() *can* be deleted.
var scope = this.Scope;
ILLocalVariable scopeVariable = null;
var endOfGet = generator.CreateLabel();
do
{
if (scope is DeclarativeScope)
{
// The variable was declared in this scope.
var variable = scope.GetDeclaredVariable(this.Name);
if (variable != null)
{
if (scope.ExistsAtRuntime == false)
{
// The scope has been optimized away. The value of the variable is stored
// in an ILVariable.
// Declare an IL local variable if no storage location has been allocated yet.
if (variable.Store == null)
variable.Store = generator.DeclareVariable(typeof(object), variable.Name);
// Load the value from the variable.
generator.LoadVariable(variable.Store);
// Ensure that we match ResultType.
EmitConversion.Convert(generator, variable.Type, this.ResultType, optimizationInfo);
}
else
{
// scope.Values[index]
if (scopeVariable == null)
EmitHelpers.LoadScope(generator);
else
generator.LoadVariable(scopeVariable);
generator.CastClass(typeof(DeclarativeScope));
generator.Call(ReflectionHelpers.DeclarativeScope_Values);
generator.LoadInt32(variable.Index);
generator.LoadArrayElement(typeof(object));
}
// The variable was found - no need to search any more parent scopes.
break;
}
else
{
// The variable was not defined at compile time, but may have been
// introduced by an eval() statement.
if (optimizationInfo.MethodOptimizationHints.HasEval == true)
{
// Check the variable exists: if (scope.HasValue(variableName) == true) {
if (scopeVariable == null)
EmitHelpers.LoadScope(generator);
else
generator.LoadVariable(scopeVariable);
generator.CastClass(typeof(DeclarativeScope));
generator.LoadString(this.Name);
generator.Call(ReflectionHelpers.Scope_HasValue);
var hasValueClause = generator.CreateLabel();
generator.BranchIfFalse(hasValueClause);
// Load the value of the variable.
if (scopeVariable == null)
EmitHelpers.LoadScope(generator);
else
generator.LoadVariable(scopeVariable);
generator.CastClass(typeof(DeclarativeScope));
generator.LoadString(this.Name);
generator.Call(ReflectionHelpers.Scope_GetValue);
generator.Branch(endOfGet);
// }
generator.DefineLabelPosition(hasValueClause);
}
}
}
else
{
if (scope.ParentScope == null)
{
// Global variable access
// -------------------------------------------
// __object_cacheKey = null;
// __object_property_cachedIndex = 0;
// ...
// if (__object_cacheKey != object.InlineCacheKey)
// xxx = object.InlineGetPropertyValue("variable", out __object_property_cachedIndex, out __object_cacheKey)
// else
// xxx = object.InlinePropertyValues[__object_property_cachedIndex];
// Get a reference to the global object.
if (scopeVariable == null)
EmitHelpers.LoadScope(generator);
else
generator.LoadVariable(scopeVariable);
generator.CastClass(typeof(ObjectScope));
generator.Call(ReflectionHelpers.ObjectScope_ScopeObject);
// TODO: share these variables somehow.
var cacheKey = generator.DeclareVariable(typeof(object));
var cachedIndex = generator.DeclareVariable(typeof(int));
// Store the object into a temp variable.
var objectInstance = generator.DeclareVariable(PrimitiveType.Object);
generator.StoreVariable(objectInstance);
// if (__object_cacheKey != object.InlineCacheKey)
generator.LoadVariable(cacheKey);
generator.LoadVariable(objectInstance);
generator.Call(ReflectionHelpers.ObjectInstance_InlineCacheKey);
var elseClause = generator.CreateLabel();
generator.BranchIfEqual(elseClause);
// value = object.InlineGetProperty("property", out __object_property_cachedIndex, out __object_cacheKey)
generator.LoadVariable(objectInstance);
generator.LoadString(this.Name);
generator.LoadAddressOfVariable(cachedIndex);
generator.LoadAddressOfVariable(cacheKey);
generator.Call(ReflectionHelpers.ObjectInstance_InlineGetPropertyValue);
var endOfIf = generator.CreateLabel();
generator.Branch(endOfIf);
// else
generator.DefineLabelPosition(elseClause);
// value = object.InlinePropertyValues[__object_property_cachedIndex];
generator.LoadVariable(objectInstance);
generator.Call(ReflectionHelpers.ObjectInstance_InlinePropertyValues);
generator.LoadVariable(cachedIndex);
generator.LoadArrayElement(typeof(object));
// End of the if statement
generator.DefineLabelPosition(endOfIf);
// Check if the value is null.
generator.Duplicate();
generator.BranchIfNotNull(endOfGet);
if (scope.ParentScope != null)
generator.Pop();
}
else
{
// Gets the value of a variable in an object scope.
if (scopeVariable == null)
EmitHelpers.LoadScope(generator);
else
generator.LoadVariable(scopeVariable);
generator.CastClass(typeof(ObjectScope));
generator.Call(ReflectionHelpers.ObjectScope_ScopeObject);
generator.LoadString(this.Name);
generator.Call(ReflectionHelpers.ObjectInstance_GetPropertyValue_Object);
// Check if the value is null.
generator.Duplicate();
generator.BranchIfNotNull(endOfGet);
if (scope.ParentScope != null)
generator.Pop();
}
}
// Try the parent scope.
if (scope.ParentScope != null && scope.ExistsAtRuntime == true)
{
if (scopeVariable == null)
{
scopeVariable = generator.CreateTemporaryVariable(typeof(Scope));
EmitHelpers.LoadScope(generator);
}
else
{
generator.LoadVariable(scopeVariable);
}
generator.Call(ReflectionHelpers.Scope_ParentScope);
generator.StoreVariable(scopeVariable);
}
scope = scope.ParentScope;
} while (scope != null);
// Throw an error if the name does not exist and throwIfUnresolvable is true.
if (scope == null && throwIfUnresolvable == true)
EmitHelpers.EmitThrow(generator, ErrorType.ReferenceError, this.Name + " is not defined", optimizationInfo);
// Release the temporary variable.
if (scopeVariable != null)
generator.ReleaseTemporaryVariable(scopeVariable);
// Define a label at the end.
generator.DefineLabelPosition(endOfGet);
// Object scope references may have side-effects (because of getters) so if the value
// is to be ignored we evaluate the value then pop the value from the stack.
//if (optimizationInfo.SuppressReturnValue == true)
// generator.Pop();
}
/// <summary>
/// Generates CIL for the statement.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Generate code for the start of the statement.
var statementLocals = new StatementLocals()
{
NonDefaultBreakStatementBehavior = true, NonDefaultDebugInfoBehavior = true
};
GenerateStartOfStatement(generator, optimizationInfo, statementLocals);
// <initializer>
// if (<condition>)
// {
// <loop body>
// <increment>
// while (true) {
// if (<condition> == false)
// break;
//
// <body statements>
//
// continue-target:
// <increment>
// }
// }
// break-target:
// Set up some labels.
var continueTarget = generator.CreateLabel();
var breakTarget1 = generator.CreateLabel();
var breakTarget2 = generator.CreateLabel();
// Emit the initialization statement.
if (this.InitStatement != null)
{
this.InitStatement.GenerateCode(generator, optimizationInfo);
}
// Check the condition and jump to the end if it is false.
if (this.CheckConditionAtEnd == false && this.ConditionStatement != null)
{
#if !XBOX
if (optimizationInfo.DebugDocument != null)
{
generator.MarkSequencePoint(optimizationInfo.DebugDocument, this.ConditionStatement.DebugInfo);
}
#endif
this.Condition.GenerateCode(generator, optimizationInfo);
EmitConversion.ToBool(generator, this.Condition.ResultType);
generator.BranchIfFalse(breakTarget1);
}
// Emit the loop body.
optimizationInfo.PushBreakOrContinueInfo(this.Labels, breakTarget1, continueTarget, false);
this.Body.GenerateCode(generator, optimizationInfo);
optimizationInfo.PopBreakOrContinueInfo();
// Increment the loop variable.
if (this.IncrementStatement != null)
{
this.IncrementStatement.GenerateCode(generator, optimizationInfo);
}
// Strengthen the variable types.
List <KeyValuePair <Scope.DeclaredVariable, RevertInfo> > previousVariableTypes = null;
var previousInsideTryCatchOrFinally = optimizationInfo.InsideTryCatchOrFinally;
if (optimizationInfo.OptimizeInferredTypes == true)
{
// Keep a record of the variable types before strengthening.
previousVariableTypes = new List <KeyValuePair <Scope.DeclaredVariable, RevertInfo> >();
var typedVariables = FindTypedVariables();
foreach (var variableAndType in typedVariables)
{
var variable = variableAndType.Key;
var variableInfo = variableAndType.Value;
if (variableInfo.Conditional == false && variableInfo.Type != variable.Type)
{
// Save the previous type so we can restore it later.
var previousType = variable.Type;
previousVariableTypes.Add(new KeyValuePair <Scope.DeclaredVariable, RevertInfo>(variable, new RevertInfo()
{
Type = previousType, Variable = variable.Store
}));
// Load the existing value.
var nameExpression = new NameExpression(variable.Scope, variable.Name);
nameExpression.GenerateGet(generator, optimizationInfo, false);
// Store the typed value.
variable.Store = generator.DeclareVariable(variableInfo.Type);
variable.Type = variableInfo.Type;
nameExpression.GenerateSet(generator, optimizationInfo, previousType, false);
}
}
// The variables must be reverted even in the presence of exceptions.
if (previousVariableTypes.Count > 0)
{
generator.BeginExceptionBlock();
// Setting the InsideTryCatchOrFinally flag converts BR instructions into LEAVE
// instructions so that the finally block is executed correctly.
optimizationInfo.InsideTryCatchOrFinally = true;
}
}
// The inner loop starts here.
var startOfLoop = generator.DefineLabelPosition();
// Check the condition and jump to the end if it is false.
if (this.ConditionStatement != null)
{
#if !XBOX
if (optimizationInfo.DebugDocument != null)
{
generator.MarkSequencePoint(optimizationInfo.DebugDocument, this.ConditionStatement.DebugInfo);
}
#endif
this.Condition.GenerateCode(generator, optimizationInfo);
EmitConversion.ToBool(generator, this.Condition.ResultType);
generator.BranchIfFalse(breakTarget2);
}
// Emit the loop body.
optimizationInfo.PushBreakOrContinueInfo(this.Labels, breakTarget2, continueTarget, labelledOnly: false);
this.Body.GenerateCode(generator, optimizationInfo);
optimizationInfo.PopBreakOrContinueInfo();
// The continue statement jumps here.
generator.DefineLabelPosition(continueTarget);
// Increment the loop variable.
if (this.IncrementStatement != null)
{
this.IncrementStatement.GenerateCode(generator, optimizationInfo);
}
// Unconditionally branch back to the start of the loop.
generator.Branch(startOfLoop);
// Define the end of the loop (actually just after).
generator.DefineLabelPosition(breakTarget2);
// Revert the variable types.
if (previousVariableTypes != null && previousVariableTypes.Count > 0)
{
// Revert the InsideTryCatchOrFinally flag.
optimizationInfo.InsideTryCatchOrFinally = previousInsideTryCatchOrFinally;
// Revert the variable types within a finally block.
generator.BeginFinallyBlock();
foreach (var previousVariableAndType in previousVariableTypes)
{
var variable = previousVariableAndType.Key;
var variableRevertInfo = previousVariableAndType.Value;
// Load the existing value.
var nameExpression = new NameExpression(variable.Scope, variable.Name);
nameExpression.GenerateGet(generator, optimizationInfo, false);
// Store the typed value.
var previousType = variable.Type;
variable.Store = variableRevertInfo.Variable;
variable.Type = variableRevertInfo.Type;
nameExpression.GenerateSet(generator, optimizationInfo, previousType, false);
}
// End the exception block.
generator.EndExceptionBlock();
}
// Define the end of the loop (actually just after).
generator.DefineLabelPosition(breakTarget1);
// Generate code for the end of the statement.
GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
}
