Compiler: Avoid allocating strings with writing integer literals#12101
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DustinCampbell merged 2 commits intodotnet:mainfrom Aug 18, 2025
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Whenever the Razor compiler writes a integer value, it calls `ToString(CultureInfo.InvariantCulture)` on the integer to allocate a new string. To avoid these extra strings, this change introduces a new `CodeWriter.WriteIntegerLiteral(int)` extension method that can directly write an integer value with invariant culture. This method uses a lookup table of precomputed string values to avoid allocations.
Use the `CodeWriter.WriteIntegerLiteral` extension method in the Razor compiler to avoid extra string allocations (where possible).
davidwengier
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Aug 12, 2025
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I wonder how long a test would take if you just use [CombinatorialData] :D
chsienki
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Aug 13, 2025
| private static readonly ReadOnlyMemory<char> s_true = "true".AsMemory(); | ||
| private static readonly ReadOnlyMemory<char> s_false = "false".AsMemory(); | ||
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| private static readonly ReadOnlyMemory<char> s_zeroes = "0000000000".AsMemory(); // 10 zeros |
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Why we do we need so many zeros? We only ever need up to three, right?
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10 is the largest number of 0s in an int. We don't need the extras for this algorithm, but it seemed reasonable (at the time 😄) to just put the maximum in there.
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@chsienki: I'll go ahead and merge since you didn't block on this. However, I'm happy to make a change here if you like.
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When writing integer literals, the compiler first allocates a string using the invariant culture and then writes the string. This is pretty wasteful and the compiler writes a lot of integer literals for
#linedirectives. This change introduces a newCodeWriter.WriteIntegerLiteralfunction that writes integers directly without allocations using a lookup table.CI Build: https://dev.azure.com/dnceng/internal/_build/results?buildId=2770483&view=results
Test Insertion: https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/661077
Toolset Run: https://dev.azure.com/dnceng/internal/_build/results?buildId=2770489&view=results