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Remove now unnecessary IsKnownConstant special-casing in interpolated string handlers #83762

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merged 1 commit into from
Mar 22, 2023
Merged

Remove now unnecessary IsKnownConstant special-casing in interpolated string handlers #83762

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65 changes: 3 additions & 62 deletions src/libraries/System.Private.CoreLib/src/System/MemoryExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4040,65 +4040,6 @@ public TryWriteInterpolatedStringHandler(int literalLength, int formattedCount,
/// <returns>true if the value could be formatted to the span; otherwise, false.</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public bool AppendLiteral(string value)
{
if (RuntimeHelpers.IsKnownConstant(value))
{
// See comment on inlining and special-casing in DefaultInterpolatedStringHandler.AppendLiteral.

if (value.Length == 1)
{
Span<char> destination = _destination;
int pos = _pos;
if ((uint)pos < (uint)destination.Length)
{
destination[pos] = value[0];
_pos = pos + 1;
return true;
}

return Fail();
}

if (value.Length == 2)
{
Span<char> destination = _destination;
int pos = _pos;
if ((uint)pos < destination.Length - 1)
{
Unsafe.WriteUnaligned(
ref Unsafe.As<char, byte>(ref Unsafe.Add(ref MemoryMarshal.GetReference(destination), pos)),
Unsafe.ReadUnaligned<int>(ref Unsafe.As<char, byte>(ref value.GetRawStringData())));
_pos = pos + 2;
return true;
}

return Fail();
}

if (value.Length == 4)
{
Span<char> destination = _destination;
int pos = _pos;
if ((uint)pos < destination.Length - 3)
{
Unsafe.WriteUnaligned(
ref Unsafe.As<char, byte>(ref Unsafe.Add(ref MemoryMarshal.GetReference(destination), pos)),
Unsafe.ReadUnaligned<long>(ref Unsafe.As<char, byte>(ref value.GetRawStringData())));
_pos = pos + 4;
return true;
}

return Fail();
}
}

return AppendStringDirect(value);
}

/// <summary>Writes the specified string to the handler.</summary>
/// <param name="value">The string to write.</param>
/// <returns>true if the value could be appended to the span; otherwise, false.</returns>
private bool AppendStringDirect(string value)
{
if (value.TryCopyTo(_destination.Slice(_pos)))
{
Expand Down Expand Up @@ -4170,7 +4111,7 @@ public bool AppendFormatted<T>(T value)
s = value?.ToString();
}

return s is null || AppendStringDirect(s);
return s is null || AppendLiteral(s);
}

/// <summary>Writes the specified value to the handler.</summary>
Expand Down Expand Up @@ -4226,7 +4167,7 @@ public bool AppendFormatted<T>(T value, string? format)
s = value?.ToString();
}

return s is null || AppendStringDirect(s);
return s is null || AppendLiteral(s);
}

/// <summary>Writes the specified value to the handler.</summary>
Expand Down Expand Up @@ -4390,7 +4331,7 @@ private bool AppendCustomFormatter<T>(T value, string? format)

if (formatter is not null && formatter.Format(format, value, _provider) is string customFormatted)
{
return AppendStringDirect(customFormatted);
return AppendLiteral(customFormatted);
}

return true;
Expand Down
77 changes: 4 additions & 73 deletions ...m.Private.CoreLib/src/System/Runtime/CompilerServices/DefaultInterpolatedStringHandler.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -133,75 +133,6 @@ internal void Clear()
/// <param name="value">The string to write.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public void AppendLiteral(string value)
{
if (RuntimeHelpers.IsKnownConstant(value))
{
// AppendLiteral is expected to be called by compiler-generated code with a literal string.
// By inlining it, the method body is exposed to the constant length of that literal, allowing the JIT to
// prune away the irrelevant cases. This effectively enables multiple implementations of AppendLiteral,
// special-cased on and optimized for the literal's length. We special-case lengths 1 and 2 because
// they're very common, e.g.
// 1: ' ', '.', '-', '\t', etc.
// 2: ", ", "0x", "=>", ": ", etc.
// and length 4 because it can similarly be done with a single read/write.

if (value.Length == 1)
{
int pos = _pos;
Span<char> chars = _chars;
if ((uint)pos < (uint)chars.Length)
{
chars[pos] = value[0];
_pos = pos + 1;
}
else
{
GrowThenCopyString(value);
}
return;
}

if (value.Length == 2)
{
int pos = _pos;
if ((uint)pos < _chars.Length - 1)
{
Unsafe.WriteUnaligned(
ref Unsafe.As<char, byte>(ref Unsafe.Add(ref MemoryMarshal.GetReference(_chars), pos)),
Unsafe.ReadUnaligned<int>(ref Unsafe.As<char, byte>(ref value.GetRawStringData())));
_pos = pos + 2;
}
else
{
GrowThenCopyString(value);
}
return;
}

if (value.Length == 4)
{
int pos = _pos;
if ((uint)pos < _chars.Length - 3)
{
Unsafe.WriteUnaligned(
ref Unsafe.As<char, byte>(ref Unsafe.Add(ref MemoryMarshal.GetReference(_chars), pos)),
Unsafe.ReadUnaligned<long>(ref Unsafe.As<char, byte>(ref value.GetRawStringData())));
_pos = pos + 4;
}
else
{
GrowThenCopyString(value);
}
return;
}
}

AppendStringDirect(value);
}

/// <summary>Writes the specified string to the handler.</summary>
/// <param name="value">The string to write.</param>
private void AppendStringDirect(string value)
{
if (value.TryCopyTo(_chars.Slice(_pos)))
{
Expand Down Expand Up @@ -350,7 +281,7 @@ public void AppendFormatted<T>(T value)

if (s is not null)
{
AppendStringDirect(s);
AppendLiteral(s);
}
}

Expand Down Expand Up @@ -412,7 +343,7 @@ public void AppendFormatted<T>(T value, string? format)

if (s is not null)
{
AppendStringDirect(s);
AppendLiteral(s);
}
}

Expand Down Expand Up @@ -596,7 +527,7 @@ private void AppendCustomFormatter<T>(T value, string? format)

if (formatter is not null && formatter.Format(format, value, _provider) is string customFormatted)
{
AppendStringDirect(customFormatted);
AppendLiteral(customFormatted);
}
}

Expand Down Expand Up @@ -646,7 +577,7 @@ private void EnsureCapacityForAdditionalChars(int additionalChars)
}
}

/// <summary>Fallback for fast path in <see cref="AppendStringDirect"/> when there's not enough space in the destination.</summary>
/// <summary>Fallback for fast path in <see cref="AppendLiteral(string)"/> when there's not enough space in the destination.</summary>
/// <param name="value">The string to write.</param>
[MethodImpl(MethodImplOptions.NoInlining)]
private void GrowThenCopyString(string value)
Expand Down