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Optimize RLP length calculation #6729

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merged 6 commits into from
Feb 15, 2024
Merged

Optimize RLP length calculation #6729

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befbda1
Make Rlp.LengthOfLength branchless
PaulusParssinen Feb 14, 2024
ef66b02
Make Rlp.LengthOf almost branchless
PaulusParssinen Feb 14, 2024
879a9af
Use BinaryPrimitives in Rlp.SerializeLength
PaulusParssinen Feb 14, 2024
4d49663
Remove unnecessary OR
PaulusParssinen Feb 14, 2024
0544144
Change WriteInt16BE to WriteUInt16 per the feedback
PaulusParssinen Feb 14, 2024
6f67f59
Update Rlp.cs
benaadams Feb 15, 2024
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92 changes: 14 additions & 78 deletions src/Nethermind/Nethermind.Serialization.Rlp/Rlp.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -407,8 +407,7 @@ public static int SerializeLength(Span<byte> buffer, int position, int value)

if (value < 1 << 16)
{
buffer[position] = (byte)(value >> 8);
buffer[position + 1] = ((byte)value);
BinaryPrimitives.WriteInt16BigEndian(buffer.Slice(position), (short)value);
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return position + 2;
}

Expand All @@ -420,31 +419,14 @@ public static int SerializeLength(Span<byte> buffer, int position, int value)
return position + 3;
}

buffer[position] = (byte)(value >> 24);
buffer[position + 1] = (byte)(value >> 16);
buffer[position + 2] = (byte)(value >> 8);
buffer[position + 3] = (byte)value;
BinaryPrimitives.WriteInt32BigEndian(buffer.Slice(position), value);
return position + 4;
}

public static int LengthOfLength(int value)
{
if (value < 1 << 8)
{
return 1;
}

if (value < 1 << 16)
{
return 2;
}

if (value < 1 << 24)
{
return 3;
}

return 4;
int bits = 32 - BitOperations.LeadingZeroCount((uint)value | 1);
return (bits + 7) / 8;
}

public static byte[] SerializeLength(int value)
Expand Down Expand Up @@ -1608,74 +1590,28 @@ public static int LengthOfNonce(ulong _)

public static int LengthOf(long value)
{
// everything has a length prefix
if (value < 0)
if ((ulong)value < 128)
{
return 9;
return 1;
}

if (value < 256L * 256L * 256L * 256L * 256L * 256L * 256L)
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This wild set of if statements has always bothered me when I saw it

else
{
if (value < 256L * 256L * 256L * 256L * 256L * 256L)
{
if (value < 256L * 256L * 256L * 256L * 256L)
{
if (value < 256L * 256L * 256L * 256L)
{
if (value < 256 * 256 * 256)
{
if (value < 256 * 256)
{
if (value < 128)
{
return 1;
}

return value < 256 ? 2 : 3;
}

return 4;
}

return 5;
}

return 6;
}

return 7;
}

return 8;
// everything has a length prefix
return 1 + sizeof(ulong) - (BitOperations.LeadingZeroCount((ulong)value) / 8);
}

return 9;
}

public static int LengthOf(int value)
{
// everything has a length prefix
if (value < 0)
if ((uint)value < 128)
{
return 9; // we cast it to long now
return 1;
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}

if (value < 256 * 256 * 256)
else
{
if (value < 256 * 256)
{
if (value < 128)
{
return 1;
}

return value < 256 ? 2 : 3;
}

return 4;
// everything has a length prefix
return 1 + sizeof(uint) - (BitOperations.LeadingZeroCount((uint)value) / 8);
}

return 5;
}

public static int LengthOf(Hash256? item)
Expand Down
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