[pixel shader todo(sm<4)]
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
todo(sm<4 | msl) draw quad
probe (0, 0) rgba (2.0, 2.0, 2.0, 2.0)
uniform 0 float 1.0
todo(sm<4 | msl) draw quad
probe (0, 0) rgba (-2.0, -2.0, -2.0, -2.0)


[pixel shader todo(sm<4)]
float cond;

float4 main() : sv_target
{
    float2 r = {1, 2};
    float2 tmp;

    // invalidate r
    if (cond)
        r = float2(10, 20);

    tmp = r;
    r = tmp;
    return r.y;
}

[test]
uniform 0 float 0.0
todo(sm<4 | msl) draw quad
probe (0, 0) rgba (2.0, 2.0, 2.0, 2.0)
uniform 0 float 1.0
todo(sm<4 | msl) draw quad
probe (0, 0) rgba (20.0, 20.0, 20.0, 20.0)


[pixel shader todo(sm<4)]
float cond;

float4 main() : sv_target
{
    float2 r = {3, 4};

    // invalidate r
    if (cond)
        r = float2(30, 40);

    r = r;
    r = float2(1, r.y);

    return float4(r, 0, 0);
}

[test]
uniform 0 float 0.0
todo(sm<4 | msl) draw quad
probe (0, 0) rgba (1.0, 4.0, 0.0, 0.0)
uniform 0 float 1.0
todo(sm<4 | msl) draw quad
probe (0, 0) rgba (1.0, 40.0, 0.0, 0.0)