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Reduce allocations from creating MissingTokenWithTrivia objects #75404

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merged 2 commits into from
Oct 8, 2024
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Reduce allocations from creating MissingTokenWithTrivia objects #75404

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f497ad9
Reduce allocations from creating MissingTokenWithTrivia objects
ToddGrun Oct 5, 2024
f3b88c3
Create non-trivia version of CreateMissing
ToddGrun Oct 5, 2024
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2 changes: 1 addition & 1 deletion src/Compilers/CSharp/Portable/Syntax/InternalSyntax/SyntaxFactory.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -146,7 +146,7 @@ internal static SyntaxToken Token(GreenNode leading, SyntaxKind kind, string tex

internal static SyntaxToken MissingToken(SyntaxKind kind)
{
return SyntaxToken.CreateMissing(kind, null, null);
return SyntaxToken.CreateMissing(kind);
}

internal static SyntaxToken MissingToken(GreenNode leading, SyntaxKind kind, GreenNode trailing)
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20 changes: 19 additions & 1 deletion src/Compilers/CSharp/Portable/Syntax/InternalSyntax/SyntaxToken.cs
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Expand Up @@ -76,7 +76,7 @@ internal static SyntaxToken Create(SyntaxKind kind)
throw new ArgumentException(string.Format(CSharpResources.ThisMethodCanOnlyBeUsedToCreateTokens, kind), nameof(kind));
}

return CreateMissing(kind, null, null);
return CreateMissing(kind);
}

return s_tokensWithNoTrivia[(int)kind].Value;
Expand Down Expand Up @@ -118,6 +118,20 @@ internal static SyntaxToken Create(SyntaxKind kind, GreenNode leading, GreenNode
return new SyntaxTokenWithTrivia(kind, leading, trailing);
}

internal static SyntaxToken CreateMissing(SyntaxKind kind)
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Would it be better to instead have just one CreateMissing(SyntaxKind kind, GreenNode leading, GreenNode trailing) and do the optimization if leading is null && trailing is null?

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I'm flexible to whatever you folks want, but that's the way I started and I switched to this because:

  1. Two less null checks in the 99% case that I see called
  2. This mimics what the two Create methods do right above it by having one that handles leading/trailing and one that doesn't take them in.

{
if (kind <= LastTokenWithWellKnownText)
{
return s_missingTokensWithNoTrivia[(int)kind].Value;
}
else if (kind == SyntaxKind.IdentifierToken)
{
return s_missingIdentifierTokenWithNoTrivia;
}

return new MissingTokenWithTrivia(kind, leading: null, trailing: null);
}

internal static SyntaxToken CreateMissing(SyntaxKind kind, GreenNode leading, GreenNode trailing)
{
return new MissingTokenWithTrivia(kind, leading, trailing);
Expand All @@ -131,6 +145,9 @@ internal static SyntaxToken CreateMissing(SyntaxKind kind, GreenNode leading, Gr
private static readonly ArrayElement<SyntaxToken>[] s_tokensWithElasticTrivia = new ArrayElement<SyntaxToken>[(int)LastTokenWithWellKnownText + 1];
private static readonly ArrayElement<SyntaxToken>[] s_tokensWithSingleTrailingSpace = new ArrayElement<SyntaxToken>[(int)LastTokenWithWellKnownText + 1];
private static readonly ArrayElement<SyntaxToken>[] s_tokensWithSingleTrailingCRLF = new ArrayElement<SyntaxToken>[(int)LastTokenWithWellKnownText + 1];
private static readonly ArrayElement<SyntaxToken>[] s_missingTokensWithNoTrivia = new ArrayElement<SyntaxToken>[(int)LastTokenWithWellKnownText + 1];

private static readonly SyntaxToken s_missingIdentifierTokenWithNoTrivia = new MissingTokenWithTrivia(SyntaxKind.IdentifierToken, leading: null, trailing: null);

static SyntaxToken()
{
Expand All @@ -140,6 +157,7 @@ static SyntaxToken()
s_tokensWithElasticTrivia[(int)kind].Value = new SyntaxTokenWithTrivia(kind, SyntaxFactory.ElasticZeroSpace, SyntaxFactory.ElasticZeroSpace);
s_tokensWithSingleTrailingSpace[(int)kind].Value = new SyntaxTokenWithTrivia(kind, null, SyntaxFactory.Space);
s_tokensWithSingleTrailingCRLF[(int)kind].Value = new SyntaxTokenWithTrivia(kind, null, SyntaxFactory.CarriageReturnLineFeed);
s_missingTokensWithNoTrivia[(int)kind].Value = new MissingTokenWithTrivia(kind, leading: null, trailing: null);
}
}

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