BranchLabel.cs

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using System.Collections.Generic;
 
namespace System.Linq.Expressions.Interpreter;
 
internal sealed class BranchLabel
{
    private int _targetIndex = int.MinValue;
 
    private int _stackDepth = int.MinValue;
 
    private int _continuationStackDepth = int.MinValue;
 
    private List<int> _forwardBranchFixups;
 
    internal int LabelIndex { get; set; } = int.MinValue;
 
 
    internal bool HasRuntimeLabel => LabelIndex != int.MinValue;
 
    internal int TargetIndex => _targetIndex;
 
    internal RuntimeLabel ToRuntimeLabel()
    {
        return new RuntimeLabel(_targetIndex, _continuationStackDepth, _stackDepth);
    }
 
    internal void Mark(InstructionList instructions)
    {
        _stackDepth = instructions.CurrentStackDepth;
        _continuationStackDepth = instructions.CurrentContinuationsDepth;
        _targetIndex = instructions.Count;
        if (_forwardBranchFixups == null)
        {
            return;
        }
        foreach (int forwardBranchFixup in _forwardBranchFixups)
        {
            FixupBranch(instructions, forwardBranchFixup);
        }
        _forwardBranchFixups = null;
    }
 
    internal void AddBranch(InstructionList instructions, int branchIndex)
    {
        if (_targetIndex == int.MinValue)
        {
            if (_forwardBranchFixups == null)
            {
                _forwardBranchFixups = new List<int>();
            }
            _forwardBranchFixups.Add(branchIndex);
        }
        else
        {
            FixupBranch(instructions, branchIndex);
        }
    }
 
    internal void FixupBranch(InstructionList instructions, int branchIndex)
    {
        instructions.FixupBranch(branchIndex, _targetIndex - branchIndex);
    }
}