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Moved opcode-related logic to a respective helper
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,165 @@ | ||
| using System.Reflection; | ||
| using System.Reflection.Emit; | ||
|
|
||
| namespace HotAvalonia.Helpers; | ||
|
|
||
| /// <summary> | ||
| /// Provides helper methods for working with CIL opcodes. | ||
| /// </summary> | ||
| internal static class OpCodeHelper | ||
| { | ||
| /// <summary> | ||
| /// The <see cref="OpCode.Value"/> for the 'call' instruction. | ||
| /// </summary> | ||
| internal const short CallValue = 0x28; | ||
|
|
||
| /// <summary> | ||
| /// The <see cref="OpCode.Value"/> for the 'ret' instruction. | ||
| /// </summary> | ||
| internal const short RetValue = 0x2A; | ||
|
|
||
| /// <summary> | ||
| /// The <see cref="OpCode.Value"/> for the 'switch' instruction. | ||
| /// </summary> | ||
| internal const short SwitchValue = 0x45; | ||
|
|
||
| /// <summary> | ||
| /// The <see cref="OpCode.Value"/> for the 'ldstr' instruction. | ||
| /// </summary> | ||
| internal const short LdstrValue = 0x72; | ||
|
|
||
| /// <summary> | ||
| /// The <see cref="OpCode.Value"/> for the 'newobj' instruction. | ||
| /// </summary> | ||
| internal const short NewobjValue = 0x73; | ||
|
|
||
| /// <summary> | ||
| /// The flag indicating that the <see cref="OpCode"/> is represented by 2 bytes. | ||
| /// </summary> | ||
| private const int Int16OpCodeFlag = 0xFE00; | ||
|
|
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| /// <summary> | ||
| /// The marker value for two-byte opcodes. | ||
| /// </summary> | ||
| private const int Int16OpCodeMarker = 0xFE; | ||
|
|
||
| /// <summary> | ||
| /// The instruction set containing all <see cref="OpCode"/> instances. | ||
| /// </summary> | ||
| private static readonly Lazy<OpCode[]> s_opCodes = new(CreateInstructionSet, isThreadSafe: true); | ||
|
|
||
| /// <summary> | ||
| /// Attempts to read an <see cref="OpCode"/> from the given IL span. | ||
| /// </summary> | ||
| /// <param name="il">The span containing the IL bytecode.</param> | ||
| /// <param name="opCode">When this method returns, contains the <see cref="OpCode"/> if the method is successful.</param> | ||
| /// <returns><c>true</c> if an <see cref="OpCode"/> was successfully read; otherwise, <c>false</c>.</returns> | ||
| public static bool TryReadOpCode(ReadOnlySpan<byte> il, out OpCode opCode) | ||
| { | ||
| opCode = OpCodes.Nop; | ||
|
|
||
| if (il.IsEmpty) | ||
| return false; | ||
|
|
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| int opCodeValue = il[0]; | ||
| if (opCodeValue >= Int16OpCodeMarker) | ||
| { | ||
| if (il.Length < 1) | ||
| return false; | ||
|
|
||
| opCodeValue = (opCodeValue << 8) | il[1]; | ||
| } | ||
|
|
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| return TryGetOpCode(opCodeValue, out opCode); | ||
| } | ||
|
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| /// <summary> | ||
| /// Tries to get the <see cref="OpCode"/> associated with the given value. | ||
| /// </summary> | ||
| /// <param name="value">The opcode value.</param> | ||
| /// <param name="opCode">When this method returns, contains the <see cref="OpCode"/> if the method is successful.</param> | ||
| /// <returns><c>true</c> if the <see cref="OpCode"/> was found for the given value; otherwise, <c>false</c>.</returns> | ||
| public static bool TryGetOpCode(int value, out OpCode opCode) | ||
| { | ||
| int index = GetOpCodeIndex(value); | ||
| OpCode[] opCodes = s_opCodes.Value; | ||
| if ((uint)index < (uint)opCodes.Length) | ||
| { | ||
| opCode = opCodes[index]; | ||
| return true; | ||
| } | ||
|
|
||
| opCode = OpCodes.Nop; | ||
| return false; | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Creates an instruction set containing all <see cref="OpCode"/> instances. | ||
| /// </summary> | ||
| /// <returns>An array of <see cref="OpCode"/> instances.</returns> | ||
| private static OpCode[] CreateInstructionSet() | ||
| { | ||
| List<OpCode> opCodes = new(256); | ||
| opCodes.AddRange(ExtractAllOpCodes()); | ||
|
|
||
| int maxIndex = opCodes.Max(static x => GetOpCodeIndex(x.Value)); | ||
| int instructionSetSize = maxIndex + 1; | ||
| OpCode[] instructionSet = new OpCode[instructionSetSize]; | ||
|
|
||
| foreach (OpCode opCode in opCodes) | ||
| { | ||
| instructionSet[GetOpCodeIndex(opCode.Value)] = opCode; | ||
| } | ||
|
|
||
| return instructionSet; | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Gets the index of the given opcode in the instruction set. | ||
| /// </summary> | ||
| /// <param name="value">The opcode value.</param> | ||
| /// <returns>The index of the opcode.</returns> | ||
| private static int GetOpCodeIndex(int value) | ||
| => (value & Int16OpCodeFlag) == Int16OpCodeFlag ? (256 + (value & 0xFF)) : (value & 0xFF); | ||
|
|
||
| /// <summary> | ||
| /// Extracts all opcodes from the <see cref="OpCodes"/> class. | ||
| /// </summary> | ||
| /// <returns> | ||
| /// All opcodes defined in the <see cref="OpCodes"/> class. | ||
| /// </returns> | ||
| private static IEnumerable<OpCode> ExtractAllOpCodes() | ||
| { | ||
| FieldInfo[] fields = typeof(OpCodes).GetFields(BindingFlags.Public | BindingFlags.Static); | ||
| return fields.Where(static x => x.FieldType == typeof(OpCode)).Select(static x => (OpCode)x.GetValue(null)); | ||
| } | ||
|
|
||
| /// <summary> | ||
| /// Calculates the size of the operand associated with the given opcode. | ||
| /// </summary> | ||
| /// <param name="opCode">The operation code in question.</param> | ||
| /// <returns> | ||
| /// The size of the operand in bytes; or 0 if the opcode has no operand. | ||
| /// </returns> | ||
| public static int GetOperandSize(this OpCode opCode) | ||
| => opCode.Size is 0 ? 0 : GetOperandSize(opCode.OperandType); | ||
|
|
||
| /// <summary> | ||
| /// Determines the size of an operand based on its type. | ||
| /// </summary> | ||
| /// <param name="operandType">The type of the operand.</param> | ||
| /// <returns> | ||
| /// The size of the operand in bytes. | ||
| /// </returns> | ||
| public static int GetOperandSize(this OperandType operandType) => operandType switch | ||
| { | ||
| OperandType.InlineBrTarget or OperandType.InlineField or OperandType.InlineI | ||
| or OperandType.InlineMethod or OperandType.InlineSig or OperandType.InlineString | ||
| or OperandType.InlineSwitch or OperandType.InlineTok or OperandType.InlineType | ||
| or OperandType.ShortInlineR => sizeof(int), | ||
| OperandType.InlineI8 or OperandType.InlineR => sizeof(long), | ||
| OperandType.InlineVar => sizeof(short), | ||
| OperandType.ShortInlineBrTarget or OperandType.ShortInlineI or OperandType.ShortInlineVar => sizeof(byte), | ||
| _ => 0, | ||
| }; | ||
| } |
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