[pixel shader fail(sm<6) todo(sm>=4)]
// Overlapping register(cX) reservations are not allowed except on SM6, where they are aliased.
// On SM1 this gives hr 0x88760b59.
float a : register(c0);
float b : register(c0);

float4 main() : sv_target
{
    return a + b;
}


[pixel shader]
// It is not required to provide a register(cX) for all elements in the $Globals buffer.
float4 a; // will get register(c1)
float4 b : register(c0);

float4 main() : sv_target
{
    return float4(a.xw, b.yz);
}

[test]
uniform 0 float4 0.1 0.2 0.3 0.4
uniform 4 float4 1.1 1.2 1.3 1.4
draw quad
todo(sm>=4 & sm<6) probe all rgba (1.1, 1.4, 0.2, 0.3)


[pixel shader]
float4 a[3]; // will get register(c3)
float4 b[2] : register(c1);

float4 main() : sv_target
{
    return float4(a[1].xy, b[0].zw);
}

[test]
uniform 0 float4 0.1 0.2 0.3 0.4
uniform 4 float4 1.1 1.2 1.3 1.4
uniform 8 float4 2.1 2.2 2.3 2.4
uniform 12 float4 3.1 3.2 3.3 3.4
uniform 16 float4 4.1 4.2 4.3 4.4
draw quad
todo(sm>=4 & sm<6) probe all rgba (4.1, 4.2, 1.3, 1.4)


[require]
shader model < 4.0

[pixel shader]
float a : register(c2);
float b; // will get register c0 in SM1

float4 main() : sv_target
{
    return float4(a, b, 0.0, 0.0);
}

[test]
uniform 0 float4 0.1 0.2 0.3 0.4
uniform 4 float4 1.1 1.2 1.3 1.4
uniform 8 float4 2.1 2.2 2.3 2.4
uniform 12 float4 3.1 3.2 3.3 3.4
draw quad
probe all rgba (2.1, 0.1, 0.0, 0.0)


[require]
shader model >= 4.0

[pixel shader]
float a : register(c2);
float b; // will get offset equivalent to c2.y in SM4 and SM6

float4 main() : sv_target
{
    return float4(a, b, 0.0, 0.0);
}

[test]
uniform 0 float4 0.1 0.2 0.3 0.4
uniform 4 float4 1.1 1.2 1.3 1.4
uniform 8 float4 2.1 2.2 2.3 2.4
uniform 12 float4 3.1 3.2 3.3 3.4
draw quad
todo(sm<6) probe all rgba (2.1, 2.2, 0.0, 0.0)


[require]
shader model >= 6.0

[pixel shader]
// Variables with overlapping register(cX) reservations are aliased in SM6.
float2 a : register(c2);
float3 b : register(c2);

float4 main() : sv_target
{
    return float4(a, b.yz);
}

[test]
uniform 0 float4 0.1 0.2 0.3 0.4
uniform 4 float4 1.1 1.2 1.3 1.4
uniform 8 float4 2.1 2.2 2.3 2.4
draw quad
probe all rgba (2.1, 2.2, 2.2, 2.3)


% Results differ between SM1 and SM4 because in the latter variables can share the same register,
% using different writemasks.
[require]
shader model < 4.0

[pixel shader]
struct
{
    float2 a;
    float b;
} apple : register(c2);

float4 main() : sv_target
{
    return float4(apple.a, apple.b, 0);
}

[test]
uniform 0 float4 0.1 0.2 0.3 0.4
uniform 4 float4 1.1 1.2 1.3 1.4
uniform 8 float4 2.1 2.2 2.3 2.4
uniform 12 float4 3.1 3.2 3.3 3.4
draw quad
probe all rgba (2.1, 2.2, 3.1, 0.0)


[require]
shader model >= 4.0

[pixel shader]
struct
{
    float2 a;
    float b;
} apple : register(c2);

float4 main() : sv_target
{
    return float4(apple.a, apple.b, 0);
}

[test]
uniform 0 float4 0.1 0.2 0.3 0.4
uniform 4 float4 1.1 1.2 1.3 1.4
uniform 8 float4 2.1 2.2 2.3 2.4
uniform 12 float4 3.1 3.2 3.3 3.4
draw quad
todo(sm<6) probe all rgba (2.1, 2.2, 2.3, 0.0)


[pixel shader]
// On SM4, register(cX) has no effect unless in the $Globals buffer.
cbuffer extra
{
    float a : register(c1);
};

float4 main() : sv_target
{
    return a;
}

[test]
uniform 0 float 100
uniform 4 float 101
draw quad
probe all rgba (100, 100, 100, 100)


[pixel shader fail(sm>=6)]
// On SM4 register(cX) has no effect unless in the $Globals buffer.
float4 main(uniform float a : register(c1)) : sv_target
{
    return a;
}

[test]
uniform 0 float 100
uniform 4 float 101
draw quad
probe all rgba (100, 100, 100, 100)

[pixel shader todo]
cbuffer c
{
    float a : packoffset(c1);
    float b : packoffset(c2) : register(c1);
    // ^ register(c1) ignored for cbuffer that is not $Globals.
}

float4 main() : sv_target
{
    return float4(a, b, 0, 0);
}

[test]
uniform 0 float 200
uniform 4 float 201
uniform 8 float 202
todo(sm<6) draw quad
todo(sm<6) probe all rgba (201.0, 202.0, 0.0, 0.0)


[pixel shader fail(sm<4)]
int k : register(i0); // register(cX) is also required.

float4 main() : sv_target
{
    return k;
}


[require]
% All shader models.

% In SM1, most variables are needed in the "c" register group, for float operations.
% If a variable is needed in the "c" register group, register() reservations in other groups can be
% provided only if a register(cX) reservation is also provided.

[pixel shader fail(sm<4) todo(sm<4)]
int k : register(i0);
// ^^ register(cX) is also required in SM1.

float4 main() : sv_target
{
    return k;
}

[pixel shader todo]
int k : register(i0) : register(c1);
// Shader compiles because a "c" register reservation is provided for "k".

float4 main() : sv_target
{
    return k;
}


[require]
shader model >= 3.0
% model 2.0 doesn't support unrollable loops.

[pixel shader todo(sm<4)]
int k : register(i0);
// ^^ register(cX) is not required since "k" is just needed in the "i" register group.

float4 main() : sv_target
{
    float f = 0;

    for (int i = 0; i < k; ++i)
        f += i;
    return f;
}


[pixel shader todo]
int k : register(c0) : register(b0);
// ^^ unlike the "c" register group, a reservation is not required for the "i" group, even though "k" is needed on it.

float4 main() : sv_target
{
    float f = 0;

    for (int i = 0; i < k; ++i)
        f += i;
    return f;
}