The following code does not work correctly when compiled with DMD 2.061 with -O flag:

import std.stdio;
import core.simd;

// alias float4 T; // internal compiler error
alias int4 T;  // wrong result

T foo(T a)
{
    return -a;
}

void main()
{
    auto a = foo([0, 1, 2, 3]);
    writeln(a.array);
}

If T is float4, I get internal compiler error:

Internal error: ../ztc/cgxmm.c 57

If T is int4, the code compiles, but prints this when I run it (the first number is different each time, the other three stay the same):

[-1111986510, 32712, 0, 0]

If I don't use -O flag, the code compiles and works correctly for both int4 and float4.