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Votes

0

Found in

2021.3.34f1

2022.3.17f1

2023.2.5f1

2023.3.0b3

6000.0.0b11

Issue ID

UUM-60501

Regression

No

"builtin functions must be directly called" errors are thrown when building for WebGL

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How to reproduce:
1. Open the attached project "unity_project.zip"
2. Build the project for WebGL

Expected results: Build is successful
Actual results: Build fails with errors "builtin functions must be directly called"

Reproducible with: 2021.3.34f1, 2022.3.17f1, 2023.2.5f1, 2023.3.0b3

Reproducible on: Windows 10 22H2
Not reproducible on: No other environment tested

  1. Resolution Note:

    This is an unsupported use of the DllImport attribute. Native functions called through DllImport need to be compatible with .NET Platform Invoke(https://learn.microsoft.com/en-us/dotnet/standard/native-interop/pinvoke).
    Builtin compiler functions such as __builtin_expect, __builtin_clz, or __builtin_ctz cannot be called through function pointers/pinvoke but must be called directly by C/C++ code. Even if this was supported they wouldn't have the expected effect as the compiler uses them as hints to optimize code. This isn't possible when the function call crosses the managed/unmanaged code barrier.
    As a workaround I would suggest moving all the C# functions(PutLE16, PutLE24, PutLE32, BitsLog2Floor, BitsCtz) that use the __builtin_* functions to a C or C++ file in "Assets/Plugins/WebGL" and instead call these functions from the C# code using the DllImport attribute.

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