HLSL: using arrays within a structure

Question

I came across strange HLSL behavior. I am trying to use an array that is contained within a structure, for example (pixel shader code):

struct VSOUT {
    float4 projected : SV_POSITION;
    float3 pos: POSITION;
    float3 normal : NORMAL;
};


struct Something  {
    float a[17];
};


float4 shMain (VSOUT input) : SV_Target {
    Something s;

    for (int i = 0; i < (int)(input.pos.x * 800); ++i)
        s.a[(int)input.pos.x] = input.pos.x;

    return col * s.a[(int)input.pos.x];
}

The code doesn't make sense logically, it's just a sample. The problem is that when I try to compile this code, I get the following error (line 25 is the line for the loop):

(25.7): Error X3511: Forcing the loop to deploy, but the deployment failed.

, ( float a[17] shMain), , .

: DirectX (unrollable) for-loop ? ? , ?

4.0, DirectX 10 SDK 2010 .

EDIT: , Something :

struct VSOUT {
    float4 projected : SV_POSITION;
    float3 pos: POSITION;
    float3 normal : NORMAL;
};


float4 shMain (VSOUT input) : SV_Target {
    float a[17];  // Direct declaration of the array

    for (int i = 0; i < (int)(input.pos.x * 800); ++i)
        a[(int)input.pos.x] = input.pos.x;

    return col * a[(int)input.pos.x];
}

. , [loop] for-loop, , ( ).

Answer 1

, , 2x2 ( ). , fxc for, .

[loop] , ?