DXCompiler segfaults when it's impossible to allocate clip/cull registers

Description
DXCompiler segfaults when trying to compile shaders in which it's impossible to allocate clip/cull registers.

Steps to Reproduce
Compile this shader with DXC (profile vs_6_0):

struct vs_out
{
    float4 position : SV_Position;
    float clip[3] : SV_ClipDistance;
};

void main(uint id : SV_VertexID, out vs_out o)
{
    o.position = float4(0.0f, 0.0f, 0.0f, 1.0f);
    o.clip[0] = 1.0f;
    o.clip[1] = 1.0f;
    o.clip[2] = 1.0f;
}

The compiler will segfault.

Also see on Compiler Explorer.

Other shaders will cause the same behavior:

struct vs_out
{
    float4 position : SV_Position;
    float clip[2] : SV_ClipDistance1;
};

void main(uint id : SV_VertexID, out vs_out o)
{
    o.position = float4(0.0f, 0.0f, 0.0f, 1.0f);
    o.clip[0] = 1.0f;
    o.clip[1] = 1.0f;
}

static const float2 vertices[3] =
{
    {-1.0f,  1.0f},
    { 3.0f,  1.0f},
    {-1.0f, -3.0f},
};

struct vs_out
{
    float4 position : SV_Position;
    float2 clip : SV_ClipDistance;
    float3 clip2 : SV_ClipDistance1;
    float3 cull : SV_CullDistance;
};

void main(uint id : SV_VertexID, out vs_out o)
{
    const float2 pos = vertices[id];
    o.position = float4(pos, 0.0f, 1.0f);
    o.clip = 1.0f;
    o.clip2 = 1.0f;
    o.cull = 1.0f;
}

static const float2 vertices[3] =
{
    {-1.0f,  1.0f},
    { 3.0f,  1.0f},
    {-1.0f, -3.0f},
};

struct vs_out
{
    float4 position : SV_Position;
    float2 clip : SV_ClipDistance;
    float3 clip2 : SV_ClipDistance1;
    float1 cull : SV_CullDistance;
    float2 cull2 : SV_CullDistance1;
};

void main(uint id : SV_VertexID, out vs_out o)
{
    const float2 pos = vertices[id];
    o.position = float4(pos, 0.0f, 1.0f);
    o.clip = 1.0f;
    o.clip2 = 1.0f;
    o.cull = 1.0f;
    o.cull2 = 1.0f;
}

Actual Behavior
The shader is indeed invalid (you cannot allocate three registers for clip/cull distances), so I expect an error message, but not a segfault. The same applies to the other shaders, except that they fail for different reasons (all related to allocating clip/cull registers).

Environment

• DXC version: libdxcompiler.so: 1.8(dev;4662-416fab6b); libdxil.so: 1.8
• Host Operating System: Debian unstable

Start by compiling the provided HLSL shaders with DXC using the vs_6_0 profile and confirm the clip/cull register-allocation failure. Trace the compiler path that handles these allocations and replace the segfault with an error diagnostic; done means all listed invalid shaders fail without crashing.