GotoInstruction.cs

Go to the documentation of this file.

namespace System.Linq.Expressions.Interpreter;
 
internal sealed class GotoInstruction : IndexedBranchInstruction
{
    private static readonly GotoInstruction[] s_cache = new GotoInstruction[256];
 
    private readonly bool _hasResult;
 
    private readonly bool _hasValue;
 
    private readonly bool _labelTargetGetsValue;
 
    public override string InstructionName => "Goto";
 
    public override int ConsumedStack
    {
        get
        {
            if (!_hasValue)
            {
                return 0;
            }
            return 1;
        }
    }
 
    public override int ProducedStack
    {
        get
        {
            if (!_hasResult)
            {
                return 0;
            }
            return 1;
        }
    }
 
    private GotoInstruction(int targetIndex, bool hasResult, bool hasValue, bool labelTargetGetsValue)
        : base(targetIndex)
    {
        _hasResult = hasResult;
        _hasValue = hasValue;
        _labelTargetGetsValue = labelTargetGetsValue;
    }
 
    internal static GotoInstruction Create(int labelIndex, bool hasResult, bool hasValue, bool labelTargetGetsValue)
    {
        if (labelIndex < 32)
        {
            int num = (8 * labelIndex) | (labelTargetGetsValue ? 4 : 0) | (hasResult ? 2 : 0) | (hasValue ? 1 : 0);
            return s_cache[num] ?? (s_cache[num] = new GotoInstruction(labelIndex, hasResult, hasValue, labelTargetGetsValue));
        }
        return new GotoInstruction(labelIndex, hasResult, hasValue, labelTargetGetsValue);
    }
 
    public override int Run(InterpretedFrame frame)
    {
        object obj = (_hasValue ? frame.Pop() : Interpreter.NoValue);
        return frame.Goto(_labelIndex, _labelTargetGetsValue ? obj : Interpreter.NoValue, gotoExceptionHandler: false);
    }
}