perf: optimise SyntaxNodeComparer by TimothyMakkison · Pull Request #1730 · belav/csharpier (original) (raw)

belav added a commit that referenced this pull request

Dec 31, 2025

It appears that SyntaxNodeComparer is run after a file is formated, optimisation here may be impactful

• Prevent null Func<T, T, Result> allocations (still seeing some in the profiler, no idea how to sotp this)
• Prevent boxing of SyntaxTokenList, SyntaxNodeOrTokenList
• Use OrderBy.ToArray instead of OrderBy.ToList
• Create AllSeparatorsButLast to prevent boxing SeparatedSyntaxList<SyntaxNode> and IEnumerable creation

I have some other idea, but I'm focusing on the unhappy path right now.

Benchmark (comparing complexCode)

Before

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Gen2 | Allocated | |--------------------------- |---------:|--------:|--------:|----------:|----------:|----------:|----------:| | Default_SyntaxNodeComparer | 229.1 ms | 4.55 ms | 7.60 ms | 5000.0000 | 3000.0000 | 1000.0000 | 40.53 MB |

After

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Allocated | |--------------------------- |---------:|--------:|--------:|----------:|----------:|----------:| | Default_SyntaxNodeComparer | 187.4 ms | 3.51 ms | 7.64 ms | 3000.0000 | 1000.0000 | 31.39 MB |

Co-authored-by: Bela VanderVoort twobitbela@gmail.com

belav added a commit that referenced this pull request

Feb 20, 2026

It appears that SyntaxNodeComparer is run after a file is formated, optimisation here may be impactful

• Prevent null Func<T, T, Result> allocations (still seeing some in the profiler, no idea how to sotp this)
• Prevent boxing of SyntaxTokenList, SyntaxNodeOrTokenList
• Use OrderBy.ToArray instead of OrderBy.ToList
• Create AllSeparatorsButLast to prevent boxing SeparatedSyntaxList<SyntaxNode> and IEnumerable creation

I have some other idea, but I'm focusing on the unhappy path right now.

Benchmark (comparing complexCode)

Before

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Gen2 | Allocated | |--------------------------- |---------:|--------:|--------:|----------:|----------:|----------:|----------:| | Default_SyntaxNodeComparer | 229.1 ms | 4.55 ms | 7.60 ms | 5000.0000 | 3000.0000 | 1000.0000 | 40.53 MB |

After

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Allocated | |--------------------------- |---------:|--------:|--------:|----------:|----------:|----------:| | Default_SyntaxNodeComparer | 187.4 ms | 3.51 ms | 7.64 ms | 3000.0000 | 1000.0000 | 31.39 MB |

Co-authored-by: Bela VanderVoort twobitbela@gmail.com

belav added a commit that referenced this pull request

Mar 12, 2026

It appears that SyntaxNodeComparer is run after a file is formated, optimisation here may be impactful

• Prevent null Func<T, T, Result> allocations (still seeing some in the profiler, no idea how to sotp this)
• Prevent boxing of SyntaxTokenList, SyntaxNodeOrTokenList
• Use OrderBy.ToArray instead of OrderBy.ToList
• Create AllSeparatorsButLast to prevent boxing SeparatedSyntaxList<SyntaxNode> and IEnumerable creation

I have some other idea, but I'm focusing on the unhappy path right now.

Benchmark (comparing complexCode)

Before

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Gen2 | Allocated | |--------------------------- |---------:|--------:|--------:|----------:|----------:|----------:|----------:| | Default_SyntaxNodeComparer | 229.1 ms | 4.55 ms | 7.60 ms | 5000.0000 | 3000.0000 | 1000.0000 | 40.53 MB |

After

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Allocated | |--------------------------- |---------:|--------:|--------:|----------:|----------:|----------:| | Default_SyntaxNodeComparer | 187.4 ms | 3.51 ms | 7.64 ms | 3000.0000 | 1000.0000 | 31.39 MB |

Co-authored-by: Bela VanderVoort twobitbela@gmail.com

belav added a commit that referenced this pull request

Apr 4, 2026

It appears that SyntaxNodeComparer is run after a file is formated, optimisation here may be impactful

• Prevent null Func<T, T, Result> allocations (still seeing some in the profiler, no idea how to sotp this)
• Prevent boxing of SyntaxTokenList, SyntaxNodeOrTokenList
• Use OrderBy.ToArray instead of OrderBy.ToList
• Create AllSeparatorsButLast to prevent boxing SeparatedSyntaxList<SyntaxNode> and IEnumerable creation

I have some other idea, but I'm focusing on the unhappy path right now.

Benchmark (comparing complexCode)

Before

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Gen2 | Allocated | |--------------------------- |---------:|--------:|--------:|----------:|----------:|----------:|----------:| | Default_SyntaxNodeComparer | 229.1 ms | 4.55 ms | 7.60 ms | 5000.0000 | 3000.0000 | 1000.0000 | 40.53 MB |

After

| Method | Mean | Error | StdDev | Gen0 | Gen1 | Allocated | |--------------------------- |---------:|--------:|--------:|----------:|----------:|----------:| | Default_SyntaxNodeComparer | 187.4 ms | 3.51 ms | 7.64 ms | 3000.0000 | 1000.0000 | 31.39 MB |

Co-authored-by: Bela VanderVoort twobitbela@gmail.com

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