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Unity Engine

C#/.NET System namespace support

Read time 2 minutesLast updated 12 days ago
Burst provides support for some of the 
System
namespace, transforming these into Burst compatible variants in the Burst compiler.

System.Math

Burst supports all methods that 
System.Math
declares, with the following exceptions:
  • double IEEERemainder(double x, double y)
    is only supported when Api Compatibility Level is set to .NET Standard 2.1 in project settings

System.IntPtr

Burst supports all methods of 
System.IntPtr
/
System.UIntPtr
, including the static fields 
IntPtr.Zero
and 
IntPtr.Size

System.Threading.Interlocked

Burst supports atomic memory intrinsics for all methods provided by 
System.Threading.Interlocked
(for example, 
Interlocked.Increment
).
Make sure that the source location of the interlocked methods are naturally aligned. For example, the alignment of the pointer is a multiple of the pointed-to-type:
[StructLayout(LayoutKind.Explicit)]struct Foo{    [FieldOffset(0)] public long a;    [FieldOffset(5)] public long b;    public long AtomicReadAndAdd()    {        return Interlocked.Read(ref a) + Interlocked.Read(ref b);    }}
If the pointer to the struct 
Foo
has an alignment of 8, which is the natural alignment of a 
long
value, the 
Interlocked.Read
of 
a
would be successful because it lies on a naturally aligned address. However, 
b
would not be successful and undefined behavior happens at the load of 
b
as a result.

System.Threading.Thread

Burst supports the 
MemoryBarrier
method of 
System.Threading.Thread
.

System.Threading.Volatile

Burst supports the non-generic variants of 
Read
and 
Write
provided by 
System.Threading.Volatile
.

System.HashCode

Burst supports all methods of 
HashCode
except for 
HashCode.Add<T>(T, IEqualityComparer<T>)
.
However, Burst does not guarantee compatibility of results with the .NET implementation. As a consequence, 
HashCode
functions might produce different results when running in Burst versus other runtime environments such as Mono.
For example, the value produced by 
HashCode.Combine
is different when run on Burst compared to managed code, because Burst doesn't have access to the seed value used by the managed implementation.

Additional resources