float4 main(float f : TEXCOORD0, uint2 i : TEXCOORD1) : SV_Target {
    float4 v;
    v[i.x] = f;
    return v[i.y].xxxx;
}

// Could not retrieve the shader metadata
  s_mov_b32                vcc_hi, #0x0000000d
  s_mov_b32                m0, s0
  v_interp_mov_f32         v6, p0, attr1.x
  v_interp_mov_f32         v2, p0, attr1.y
  v_interp_p1_f32          v7, v0, attr0.x
  v_interp_p2_f32          v7, v1, attr0.x
  v_cmp_eq_u32             vcc, 0, v6
  v_cndmask_b32            v4, 0, v7, vcc
  v_cmp_eq_u32             vcc, 1, v6
  v_cndmask_b32            v5, 0, v7, vcc
  v_cmp_eq_u32             vcc, 2, v6
  v_cndmask_b32            v3, 0, v7, vcc
  v_cmp_eq_u32             vcc, 3, v6
  v_cndmask_b32            v6, 0, v7, vcc
  v_cmp_eq_u32             vcc, 1, v2
  v_cndmask_b32            v4, v4, v5, vcc
  v_cmp_eq_u32             vcc, 2, v2
  v_cndmask_b32            v3, v4, v3, vcc
  v_cmp_eq_u32             vcc, 3, v2
  v_cndmask_b32            v2, v3, v6, vcc
  v_cvt_pkrtz_f16_f32      v2, v2, v2
  exp                      mrt0, v2, v2 compr vm done
  s_endpgm

A geometry shader is used to generate bounding boxes. While color buffer writes are disabled our boxes are still rasterized and tested against the current depth-buffer. Those fragments which pass the depth-test, indicate that our bounding box is visible, and therefore flag the object in a visibility buffer: visible[objectid] = 1. Prior the operation that buffer is cleared to zero. This method typically yields better results than HiZ as the bounding boxes are tested more accurately as their orientation and dimension is better represented.