vello/piet-gpu/shader/gen/clip_reduce.msl

#pragma clang diagnostic ignored "-Wmissing-prototypes"

#include <metal_stdlib>
#include <simd/simd.h>

using namespace metal;

struct Bic
{
    uint a;
    uint b;
};

struct ClipEl
{
    uint parent_ix;
    float4 bbox;
};

struct Alloc
{
    uint offset;
};

struct Config
{
    uint n_elements;
    uint n_pathseg;
    uint width_in_tiles;
    uint height_in_tiles;
    Alloc tile_alloc;
    Alloc bin_alloc;
    Alloc ptcl_alloc;
    Alloc pathseg_alloc;
    Alloc anno_alloc;
    Alloc trans_alloc;
    Alloc bbox_alloc;
    Alloc drawmonoid_alloc;
    Alloc clip_alloc;
    Alloc clip_bic_alloc;
    Alloc clip_stack_alloc;
    Alloc clip_bbox_alloc;
    uint n_trans;
    uint n_path;
    uint n_clip;
    uint trans_offset;
    uint linewidth_offset;
    uint pathtag_offset;
    uint pathseg_offset;
};

struct ConfigBuf
{
    Config conf;
};

struct Memory
{
    uint mem_offset;
    uint mem_error;
    uint memory[1];
};

constant uint3 gl_WorkGroupSize [[maybe_unused]] = uint3(256u, 1u, 1u);

static inline __attribute__((always_inline))
Bic bic_combine(thread const Bic& x, thread const Bic& y)
{
    uint m = min(x.b, y.a);
    return Bic{ (x.a + y.a) - m, (x.b + y.b) - m };
}

static inline __attribute__((always_inline))
void store_bic(thread const uint& ix, thread const Bic& bic, const device ConfigBuf& v_64, device Memory& v_80)
{
    uint base = (v_64.conf.clip_bic_alloc.offset >> uint(2)) + (2u * ix);
    v_80.memory[base] = bic.a;
    v_80.memory[base + 1u] = bic.b;
}

static inline __attribute__((always_inline))
float4 load_path_bbox(thread const uint& path_ix, const device ConfigBuf& v_64, device Memory& v_80)
{
    uint base = (v_64.conf.bbox_alloc.offset >> uint(2)) + (6u * path_ix);
    float bbox_l = float(v_80.memory[base]) - 32768.0;
    float bbox_t = float(v_80.memory[base + 1u]) - 32768.0;
    float bbox_r = float(v_80.memory[base + 2u]) - 32768.0;
    float bbox_b = float(v_80.memory[base + 3u]) - 32768.0;
    float4 bbox = float4(bbox_l, bbox_t, bbox_r, bbox_b);
    return bbox;
}

static inline __attribute__((always_inline))
void store_clip_el(thread const uint& ix, thread const ClipEl& el, const device ConfigBuf& v_64, device Memory& v_80)
{
    uint base = (v_64.conf.clip_stack_alloc.offset >> uint(2)) + (5u * ix);
    v_80.memory[base] = el.parent_ix;
    v_80.memory[base + 1u] = as_type<uint>(el.bbox.x);
    v_80.memory[base + 2u] = as_type<uint>(el.bbox.y);
    v_80.memory[base + 3u] = as_type<uint>(el.bbox.z);
    v_80.memory[base + 4u] = as_type<uint>(el.bbox.w);
}

kernel void main0(device Memory& v_80 [[buffer(0)]], const device ConfigBuf& v_64 [[buffer(1)]], uint3 gl_LocalInvocationID [[thread_position_in_threadgroup]], uint3 gl_GlobalInvocationID [[thread_position_in_grid]], uint3 gl_WorkGroupID [[threadgroup_position_in_grid]])
{
    threadgroup Bic sh_bic[256];
    threadgroup uint sh_parent[256];
    threadgroup uint sh_path_ix[256];
    threadgroup float4 sh_bbox[256];
    uint th = gl_LocalInvocationID.x;
    uint inp = v_80.memory[(v_64.conf.clip_alloc.offset >> uint(2)) + gl_GlobalInvocationID.x];
    bool is_push = int(inp) >= 0;
    Bic bic = Bic{ 1u - uint(is_push), uint(is_push) };
    sh_bic[gl_LocalInvocationID.x] = bic;
    for (uint i = 0u; i < 8u; i++)
    {
        threadgroup_barrier(mem_flags::mem_threadgroup);
        if ((th + (1u << i)) < 256u)
        {
            Bic other = sh_bic[gl_LocalInvocationID.x + (1u << i)];
            Bic param = bic;
            Bic param_1 = other;
            bic = bic_combine(param, param_1);
        }
        threadgroup_barrier(mem_flags::mem_threadgroup);
        sh_bic[th] = bic;
    }
    if (th == 0u)
    {
        uint param_2 = gl_WorkGroupID.x;
        Bic param_3 = bic;
        store_bic(param_2, param_3, v_64, v_80);
    }
    threadgroup_barrier(mem_flags::mem_threadgroup);
    uint size = sh_bic[0].b;
    bic = Bic{ 0u, 0u };
    if ((th + 1u) < 256u)
    {
        bic = sh_bic[th + 1u];
    }
    bool _283;
    if (is_push)
    {
        _283 = bic.a == 0u;
    }
    else
    {
        _283 = is_push;
    }
    if (_283)
    {
        uint local_ix = (size - bic.b) - 1u;
        sh_parent[local_ix] = th;
        sh_path_ix[local_ix] = inp;
    }
    threadgroup_barrier(mem_flags::mem_threadgroup);
    float4 bbox;
    if (th < size)
    {
        uint path_ix = sh_path_ix[th];
        uint param_4 = path_ix;
        bbox = load_path_bbox(param_4, v_64, v_80);
    }
    if (th < size)
    {
        uint parent_ix = sh_parent[th] + (gl_WorkGroupID.x * 256u);
        ClipEl el = ClipEl{ parent_ix, bbox };
        uint param_5 = gl_GlobalInvocationID.x;
        ClipEl param_6 = el;
        store_clip_el(param_5, param_6, v_64, v_80);
    }
}