Avoid string allocation while searching for a char #6671
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CompareInfo.IndexOf(string, char, ...) on .NET Framework has two paths: OrdinalIgnoreCase: Which goes through string.IndexOf(string, ...) Everything else: Win32's FindNLSStringEx Both paths allocate a string that represents the char. Instead just call through string.IndexOf(char) which does a flat ordinal comparison which is what we want. This was about 0.3% of allocations in devenv opening a 500 project solution.
rainersigwald
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Jul 14, 2021
rainersigwald
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Jul 14, 2021
For OrdinalIgnoreCase, this uses string.IndexOf and allocates a string. See dotnet#6671.
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Thanks! @rainersigwald Can you merge this in? I don't have permissions. |
Forgind
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Jul 15, 2021
benvillalobos
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Jul 16, 2021
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Context
CompareInfo.IndexOf(string, char, ...) on .NET Framework has two paths:
OrdinalIgnoreCase: Which goes through string.IndexOf(string, ...)
Everything else: Win32's FindNLSStringEx
Both paths allocate a string that represents the char. Instead just call through string.IndexOf(char) which does a flat ordinal comparison which is what we want. This was about 0.3% of allocations in devenv opening a 500 project solution.
I walked every instance of this across the tree and found only the ones in the PR. It doesn't look like MSBuild uses the banned API analyzer so I couldn't prevent future consumption of this.