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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System.Diagnostics;
using Microsoft.CodeAnalysis.CSharp.Symbols;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Text;
using System.Collections.Immutable;
namespace Microsoft.CodeAnalysis.CSharp
{
internal sealed partial class LocalRewriter
{
public override BoundNode VisitIfStatement(BoundIfStatement node)
{
Debug.Assert(node != null);
var rewrittenCondition = VisitExpression(node.Condition);
var rewrittenConsequence = VisitStatement(node.Consequence);
Debug.Assert(rewrittenConsequence is { });
var rewrittenAlternative = VisitStatement(node.AlternativeOpt);
var syntax = (IfStatementSyntax)node.Syntax;
// EnC: We need to insert a hidden sequence point to handle function remapping in case
// the containing method is edited while methods invoked in the condition are being executed.
if (this.Instrument && !node.WasCompilerGenerated)
{
rewrittenCondition = Instrumenter.InstrumentIfStatementCondition(node, rewrittenCondition, _factory);
}
var result = RewriteIfStatement(syntax, rewrittenCondition, rewrittenConsequence, rewrittenAlternative, node.HasErrors);
// add sequence point before the whole statement
if (this.Instrument && !node.WasCompilerGenerated)
{
result = Instrumenter.InstrumentIfStatement(node, result);
}
return result;
}
private static BoundStatement RewriteIfStatement(
SyntaxNode syntax,
BoundExpression rewrittenCondition,
BoundStatement rewrittenConsequence,
BoundStatement? rewrittenAlternativeOpt,
bool hasErrors)
{
var afterif = new GeneratedLabelSymbol("afterif");
var builder = ArrayBuilder<BoundStatement>.GetInstance();
if (rewrittenAlternativeOpt == null)
{
// if (condition)
// consequence;
//
// becomes
//
// GotoIfFalse condition afterif;
// consequence;
// afterif:
builder.Add(new BoundConditionalGoto(rewrittenCondition.Syntax, rewrittenCondition, false, afterif));
builder.Add(rewrittenConsequence);
builder.Add(BoundSequencePoint.CreateHidden());
builder.Add(new BoundLabelStatement(syntax, afterif));
var statements = builder.ToImmutableAndFree();
return new BoundStatementList(syntax, statements, hasErrors);
}
else
{
// if (condition)
// consequence;
// else
// alternative
//
// becomes
//
// GotoIfFalse condition alt;
// consequence
// goto afterif;
// alt:
// alternative;
// afterif:
var alt = new GeneratedLabelSymbol("alternative");
builder.Add(new BoundConditionalGoto(rewrittenCondition.Syntax, rewrittenCondition, false, alt));
builder.Add(rewrittenConsequence);
builder.Add(BoundSequencePoint.CreateHidden());
builder.Add(new BoundGotoStatement(syntax, afterif));
builder.Add(new BoundLabelStatement(syntax, alt));
builder.Add(rewrittenAlternativeOpt);
builder.Add(BoundSequencePoint.CreateHidden());
builder.Add(new BoundLabelStatement(syntax, afterif));
return new BoundStatementList(syntax, builder.ToImmutableAndFree(), hasErrors);
}
}
}
}
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