dotnet/roslyn
Avoid checking HasValue in nullable comparison to non-default constants
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#52 629 ouverte le 14 avr. 2021
Area-CompilersCode Gen Qualityhelp wanted
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Description
@canton7 mentioned the following in https://github.com/dotnet/roslyn/issues/44109#issuecomment-664292439
It occurs to me that, provided one side of the
==is a constant which has a non-default value, we can skip the& x.HasValuecheck altogether.
It feels like it would be a nice little win if, when comparing a System.Nullable<T> to a constant with a non-default value, we could avoid generating code to check HasValue. For example: SharpLab
void M(int? x)
{
if (x == 42)
{
System.Console.Write(1);
}
}
Could be lowered to:
void M(int? x)
{
if (x.GetValueOrDefault() == 42)
{
System.Console.Write(1);
}
}
Currently we generate:
void M(Nullable<int> x)
{
Nullable<int> num = x;
int num2 = 42;
if ((num.GetValueOrDefault() == num2) & num.HasValue)
{
Console.Write(1);
}
}