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Shrink some types.
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@wasabii
wasabii committed Aug 4, 2024
1 parent 5403fe3 commit 27eac9e
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Showing 2 changed files with 60 additions and 37 deletions.
2 changes: 1 addition & 1 deletion src/IKVM.ByteCode/OpCodeExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ public static class OpCodeExtensions
/// <param name="opcode"></param>
/// <returns></returns>
/// <exception cref="ArgumentException"></exception>
public static int GetBranchOperandSize(this OpCode opcode)
public static byte GetBranchOperandSize(this OpCode opcode)
{
switch (opcode)
{
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95 changes: 59 additions & 36 deletions src/IKVM.ByteCode/Writing/InstructionEncoder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@ public class InstructionEncoder
/// </summary>
/// <param name="Region"></param>
/// <param name="Offset"></param>
readonly record struct FixupData(Blob Region, int Offset);
readonly record struct FixupData(Blob Region, ushort Offset);

/// <summary>
/// Describes a recorded label and optionally it's absolute value.
Expand Down Expand Up @@ -102,23 +102,33 @@ public static ref FixupData GetFixup(ref LabelInfo info, int index)
/// <summary>
/// Initializes a new instance.
/// </summary>
/// <param name="_builder"></param>
public InstructionEncoder(BlobBuilder _builder)
/// <param name="builder"></param>
public InstructionEncoder(BlobBuilder builder)
{
this._builder = _builder ?? throw new ArgumentNullException(nameof(_builder));
_builder = builder ?? throw new ArgumentNullException(nameof(builder));

// JVM limits code size to 65535
if (_builder.Count >= 65535)
throw new InvalidOperationException("Maximum size of code buffer (65535) reached.");
}

/// <summary>
/// Gets the offset of the next instruction inserted.
/// </summary>
public int Offset => _builder.Count;
public ushort Offset => checked((ushort)_builder.Count);

/// <summary>
/// Reserves the specified number of bytes in the builder.
/// </summary>
/// <param name="byteCount"></param>
/// <returns></returns>
internal Blob ReserveBytes(int byteCount) => _builder.ReserveBytes(byteCount);
internal Blob ReserveBytes(ushort byteCount)
{
if (_builder.Count + byteCount > ushort.MaxValue)
throw new InvalidOperationException("Maximum size of code buffer (65535) reached.");

return _builder.ReserveBytes(byteCount);
}

/// <summary>
/// Defines a label that can later be used to mark and refer to a location in the instruction stream.
Expand Down Expand Up @@ -147,36 +157,51 @@ public InstructionEncoder DefineLabel(out LabelHandle label)
/// <summary>
/// Associates specified label with the current bytecode positon, returning the program offset of the label.
/// </summary>
/// <param name="handle"></param>
/// <param name="label"></param>
/// <param name="offset"></param>
public InstructionEncoder MarkLabel(LabelHandle handle, out int offset)
public InstructionEncoder MarkLabel(LabelHandle label, out int offset)
{
ref var label = ref _labels[handle.Id];
if (label.Value != -1)
throw new InvalidOperationException($"Label {handle.Id} has already been marked.");
ref var l = ref _labels[label.Id];
if (l.Value != -1)
throw new InvalidOperationException($"Label {label.Id} has already been marked.");

// apply new value to label
offset = Offset;
label.Value = offset;
l.Value = offset;

// apply any outstanding fixups for the label
for (int index = 0; index < label.FixupCount; index++)
ApplyFixup(ref label, ref LabelInfo.GetFixup(ref label, index));
for (int index = 0; index < l.FixupCount; index++)
ApplyFixup(ref l, ref LabelInfo.GetFixup(ref l, index));

// reset label fixups
label.FixupCount = 0;
label.Fixups = null;
l.FixupCount = 0;
l.Fixups = null;

return this;
}

/// <summary>
/// Associates specified label with the current bytecode positon.
/// </summary>
/// <param name="handle"></param>
public InstructionEncoder MarkLabel(LabelHandle handle)
/// <param name="label"></param>
public InstructionEncoder MarkLabel(LabelHandle label)
{
return MarkLabel(handle, out _);
return MarkLabel(label, out _);
}

/// <summary>
/// Gets the absolute offset of a label.
/// </summary>
/// <param name="label"></param>
/// <returns></returns>
public ushort GetLabelOffset(LabelHandle label)
{
ref var l = ref _labels[label.Id];
var v = l.Value;
if (v == -1)
throw new InvalidOperationException($"Label {l.Id} has not been marked.");

return (ushort)v;
}

/// <summary>
Expand All @@ -185,15 +210,13 @@ public InstructionEncoder MarkLabel(LabelHandle handle)
/// <param name="label"></param>
/// <param name="size"></param>
/// <param name="offset"></param>
public InstructionEncoder Label(LabelHandle label, int size, int offset)
public InstructionEncoder Label(LabelHandle label, byte size, ushort offset)
{
if (size is not 2 and not 4)
throw new ArgumentException("Label output size can only be 2 or 4 bytes.");
if (offset < 0)
throw new ArgumentOutOfRangeException("Absolute offset of label position must be positive integer.");

ref var l = ref _labels[label.Id];
var d = new FixupData(_builder.ReserveBytes(size), offset);
var d = new FixupData(ReserveBytes(size), offset);
if (l.Value == -1)
l.AddFixup(d);
else
Expand All @@ -207,7 +230,7 @@ public InstructionEncoder Label(LabelHandle label, int size, int offset)
/// </summary>
/// <param name="label"></param>
/// <param name="size"></param>
public InstructionEncoder Label(LabelHandle label, int size)
public InstructionEncoder Label(LabelHandle label, byte size)
{
return Label(label, size, Offset);
}
Expand All @@ -218,20 +241,20 @@ public InstructionEncoder Label(LabelHandle label, int size)
/// <param name="fixup"></param>
void ApplyFixup(ref LabelInfo label, ref FixupData fixup)
{
var value = label.Value;
if (value == -1)
var v = label.Value;
if (v == -1)
throw new InvalidOperationException($"Label {label.Id} has not been marked.");

var offset = value - fixup.Offset;
var o = v - fixup.Offset;
if (fixup.Region.Length == 2)
{
if (offset < short.MinValue || offset > short.MaxValue)
if (o < short.MinValue || o > short.MaxValue)
throw new InvalidOperationException($"Label {label.Id} out of range for instruction operand size.");

BinaryPrimitives.WriteInt16BigEndian(fixup.Region.GetBytes(), (short)offset);
BinaryPrimitives.WriteInt16BigEndian(fixup.Region.GetBytes(), (short)o);
}
else
BinaryPrimitives.WriteInt32BigEndian(fixup.Region.GetBytes(), offset);
BinaryPrimitives.WriteInt32BigEndian(fixup.Region.GetBytes(), o);
}

/// <summary>
Expand Down Expand Up @@ -312,7 +335,7 @@ internal void WriteSByte(sbyte value)
/// <param name="value"></param>
internal void WriteInt16(short value)
{
BinaryPrimitives.WriteInt16BigEndian(_builder.ReserveBytes(sizeof(short)).GetBytes(), value);
BinaryPrimitives.WriteInt16BigEndian(ReserveBytes(sizeof(short)).GetBytes(), value);
}

/// <summary>
Expand All @@ -321,7 +344,7 @@ internal void WriteInt16(short value)
/// <param name="value"></param>
internal void WriteInt32(int value)
{
BinaryPrimitives.WriteInt32BigEndian(_builder.ReserveBytes(sizeof(int)).GetBytes(), value);
BinaryPrimitives.WriteInt32BigEndian(ReserveBytes(sizeof(int)).GetBytes(), value);
}

/// <summary>
Expand All @@ -330,7 +353,7 @@ internal void WriteInt32(int value)
/// <param name="value"></param>
internal void WriteByte(byte value)
{
_builder.WriteBytes(value, 1);
ReserveBytes(sizeof(byte)).GetBytes().AsSpan()[0] = value;
}

/// <summary>
Expand All @@ -339,7 +362,7 @@ internal void WriteByte(byte value)
/// <param name="value"></param>
internal void WriteUInt16(ushort value)
{
BinaryPrimitives.WriteUInt16BigEndian(_builder.ReserveBytes(sizeof(ushort)).GetBytes(), value);
BinaryPrimitives.WriteUInt16BigEndian(ReserveBytes(sizeof(ushort)).GetBytes(), value);
}

/// <summary>
Expand All @@ -348,7 +371,7 @@ internal void WriteUInt16(ushort value)
/// <param name="value"></param>
internal void WriteUInt32(uint value)
{
BinaryPrimitives.WriteUInt32BigEndian(_builder.ReserveBytes(sizeof(uint)).GetBytes(), value);
BinaryPrimitives.WriteUInt32BigEndian(ReserveBytes(sizeof(uint)).GetBytes(), value);
}

/// <summary>
Expand Down Expand Up @@ -756,7 +779,7 @@ public InstructionEncoder Branch(OpCode opcode, LabelHandle label)
/// </summary>
/// <param name="defaultLabel"></param>
/// <param name="low"></param>
/// <param name="table"></param>
/// <param name="encode"></param>
public InstructionEncoder TableSwitch(LabelHandle defaultLabel, int low, Action<TableSwitchInstructionEncoder> encode)
{
if (encode is null)
Expand Down

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