[pixel shader]
float cond;

float4 main() : sv_target
{
    float4 a = {1, 2, 3, 4};
    float4 b;

    // invalidate a
    if (cond)
        a = float4(-1, -2, -3, -4);

    b = a;
    a.y = 357;
    return b.y;
}

[test]
uniform 0 float 0.0
draw quad
todo(sm<6) probe all rgba (2.0, 2.0, 2.0, 2.0)
uniform 0 float 1.0
draw quad
todo(sm<6) probe all rgba (-2.0, -2.0, -2.0, -2.0)