9d9415754b
Some support for subgroups is present starting in Metal 2.0 on both iOS and macOS. macOS gains more complete support in 10.14 (Metal 2.1). Some restrictions are present. On iOS and on macOS 10.13, the implementation of `OpGroupNonUniformElect` is incorrect: if thread 0 has already terminated or is not executing a conditional branch, the first thread that *is* will falsely believe itself not to be. Unfortunately, this operation is part of the "basic" feature set; without it, subgroups cannot be supported at all. The `SubgroupSize` and `SubgroupLocalInvocationId` builtins are only available in compute shaders (and, by extension, tessellation control shaders), despite SPIR-V making them available in all stages. This limits the usefulness of some of the subgroup operations in fragment shaders. Although Metal on macOS supports some clustered, inclusive, and exclusive operations, it does not support them all. In particular, inclusive and exclusive min, max, and, or, and xor; as well as cluster sizes other than 4 are not supported. If this becomes a problem, they could be emulated, but at a significant performance cost due to the need for non-uniform operations.
147 lines
7.1 KiB
Plaintext
147 lines
7.1 KiB
Plaintext
#pragma clang diagnostic ignored "-Wmissing-prototypes"
|
|
|
|
#include <metal_stdlib>
|
|
#include <simd/simd.h>
|
|
|
|
using namespace metal;
|
|
|
|
struct SSBO
|
|
{
|
|
float FragColor;
|
|
};
|
|
|
|
inline uint4 spvSubgroupBallot(bool value)
|
|
{
|
|
simd_vote vote = simd_ballot(value);
|
|
// simd_ballot() returns a 64-bit integer-like object, but
|
|
// SPIR-V callers expect a uint4. We must convert.
|
|
// FIXME: This won't include higher bits if Apple ever supports
|
|
// 128 lanes in an SIMD-group.
|
|
return uint4((uint)((simd_vote::vote_t)vote & 0xFFFFFFFF), (uint)(((simd_vote::vote_t)vote >> 32) & 0xFFFFFFFF), 0, 0);
|
|
}
|
|
|
|
inline bool spvSubgroupBallotBitExtract(uint4 ballot, uint bit)
|
|
{
|
|
return !!extract_bits(ballot[bit / 32], bit % 32, 1);
|
|
}
|
|
|
|
inline uint spvSubgroupBallotFindLSB(uint4 ballot)
|
|
{
|
|
return select(ctz(ballot.x), select(32 + ctz(ballot.y), select(64 + ctz(ballot.z), select(96 + ctz(ballot.w), uint(-1), ballot.w == 0), ballot.z == 0), ballot.y == 0), ballot.x == 0);
|
|
}
|
|
|
|
inline uint spvSubgroupBallotFindMSB(uint4 ballot)
|
|
{
|
|
return select(128 - (clz(ballot.w) + 1), select(96 - (clz(ballot.z) + 1), select(64 - (clz(ballot.y) + 1), select(32 - (clz(ballot.x) + 1), uint(-1), ballot.x == 0), ballot.y == 0), ballot.z == 0), ballot.w == 0);
|
|
}
|
|
|
|
inline uint spvSubgroupBallotBitCount(uint4 ballot)
|
|
{
|
|
return popcount(ballot.x) + popcount(ballot.y) + popcount(ballot.z) + popcount(ballot.w);
|
|
}
|
|
|
|
inline uint spvSubgroupBallotInclusiveBitCount(uint4 ballot, uint gl_SubgroupInvocationID)
|
|
{
|
|
uint4 mask = uint4(extract_bits(0xFFFFFFFF, 0, min(gl_SubgroupInvocationID + 1, 32u)), extract_bits(0xFFFFFFFF, 0, (uint)max((int)gl_SubgroupInvocationID + 1 - 32, 0)), uint2(0));
|
|
return spvSubgroupBallotBitCount(ballot & mask);
|
|
}
|
|
|
|
inline uint spvSubgroupBallotExclusiveBitCount(uint4 ballot, uint gl_SubgroupInvocationID)
|
|
{
|
|
uint4 mask = uint4(extract_bits(0xFFFFFFFF, 0, min(gl_SubgroupInvocationID, 32u)), extract_bits(0xFFFFFFFF, 0, (uint)max((int)gl_SubgroupInvocationID - 32, 0)), uint2(0));
|
|
return spvSubgroupBallotBitCount(ballot & mask);
|
|
}
|
|
|
|
template<typename T>
|
|
inline bool spvSubgroupAllEqual(T value)
|
|
{
|
|
return simd_all(value == simd_broadcast_first(value));
|
|
}
|
|
|
|
template<>
|
|
inline bool spvSubgroupAllEqual(bool value)
|
|
{
|
|
return simd_all(value) || !simd_any(value);
|
|
}
|
|
|
|
kernel void main0(device SSBO& _9 [[buffer(0)]], uint gl_NumSubgroups [[simdgroups_per_threadgroup]], uint gl_SubgroupID [[simdgroup_index_in_threadgroup]], uint gl_SubgroupSize [[thread_execution_width]], uint gl_SubgroupInvocationID [[thread_index_in_simdgroup]])
|
|
{
|
|
uint4 gl_SubgroupEqMask = 27 > 32 ? uint4(0, (1 << (gl_SubgroupInvocationID - 32)), uint2(0)) : uint4(1 << gl_SubgroupInvocationID, uint3(0));
|
|
uint4 gl_SubgroupGeMask = uint4(extract_bits(0xFFFFFFFF, min(gl_SubgroupInvocationID, 32u), (uint)max(min((int)gl_SubgroupSize, 32) - (int)gl_SubgroupInvocationID, 0)), extract_bits(0xFFFFFFFF, (uint)max((int)gl_SubgroupInvocationID - 32, 0), (uint)max((int)gl_SubgroupSize - (int)max(gl_SubgroupInvocationID, 32u), 0)), uint2(0));
|
|
uint4 gl_SubgroupGtMask = uint4(extract_bits(0xFFFFFFFF, min(gl_SubgroupInvocationID + 1, 32u), (uint)max(min((int)gl_SubgroupSize, 32) - (int)gl_SubgroupInvocationID - 1, 0)), extract_bits(0xFFFFFFFF, (uint)max((int)gl_SubgroupInvocationID + 1 - 32, 0), (uint)max((int)gl_SubgroupSize - (int)max(gl_SubgroupInvocationID + 1, 32u), 0)), uint2(0));
|
|
uint4 gl_SubgroupLeMask = uint4(extract_bits(0xFFFFFFFF, 0, min(gl_SubgroupInvocationID + 1, 32u)), extract_bits(0xFFFFFFFF, 0, (uint)max((int)gl_SubgroupInvocationID + 1 - 32, 0)), uint2(0));
|
|
uint4 gl_SubgroupLtMask = uint4(extract_bits(0xFFFFFFFF, 0, min(gl_SubgroupInvocationID, 32u)), extract_bits(0xFFFFFFFF, 0, (uint)max((int)gl_SubgroupInvocationID - 32, 0)), uint2(0));
|
|
_9.FragColor = float(gl_NumSubgroups);
|
|
_9.FragColor = float(gl_SubgroupID);
|
|
_9.FragColor = float(gl_SubgroupSize);
|
|
_9.FragColor = float(gl_SubgroupInvocationID);
|
|
simdgroup_barrier(mem_flags::mem_device | mem_flags::mem_threadgroup | mem_flags::mem_texture);
|
|
simdgroup_barrier(mem_flags::mem_device | mem_flags::mem_threadgroup | mem_flags::mem_texture);
|
|
simdgroup_barrier(mem_flags::mem_device);
|
|
simdgroup_barrier(mem_flags::mem_threadgroup);
|
|
simdgroup_barrier(mem_flags::mem_texture);
|
|
bool elected = simd_is_first();
|
|
_9.FragColor = float4(gl_SubgroupEqMask).x;
|
|
_9.FragColor = float4(gl_SubgroupGeMask).x;
|
|
_9.FragColor = float4(gl_SubgroupGtMask).x;
|
|
_9.FragColor = float4(gl_SubgroupLeMask).x;
|
|
_9.FragColor = float4(gl_SubgroupLtMask).x;
|
|
float4 broadcasted = simd_broadcast(float4(10.0), 8u);
|
|
float3 first = simd_broadcast_first(float3(20.0));
|
|
uint4 ballot_value = spvSubgroupBallot(true);
|
|
bool inverse_ballot_value = spvSubgroupBallotBitExtract(ballot_value, gl_SubgroupInvocationID);
|
|
bool bit_extracted = spvSubgroupBallotBitExtract(uint4(10u), 8u);
|
|
uint bit_count = spvSubgroupBallotBitCount(ballot_value);
|
|
uint inclusive_bit_count = spvSubgroupBallotInclusiveBitCount(ballot_value, gl_SubgroupInvocationID);
|
|
uint exclusive_bit_count = spvSubgroupBallotExclusiveBitCount(ballot_value, gl_SubgroupInvocationID);
|
|
uint lsb = spvSubgroupBallotFindLSB(ballot_value);
|
|
uint msb = spvSubgroupBallotFindMSB(ballot_value);
|
|
uint shuffled = simd_shuffle(10u, 8u);
|
|
uint shuffled_xor = simd_shuffle_xor(30u, 8u);
|
|
uint shuffled_up = simd_shuffle_up(20u, 4u);
|
|
uint shuffled_down = simd_shuffle_down(20u, 4u);
|
|
bool has_all = simd_all(true);
|
|
bool has_any = simd_any(true);
|
|
bool has_equal = spvSubgroupAllEqual(0);
|
|
has_equal = spvSubgroupAllEqual(true);
|
|
float4 added = simd_sum(float4(20.0));
|
|
int4 iadded = simd_sum(int4(20));
|
|
float4 multiplied = simd_product(float4(20.0));
|
|
int4 imultiplied = simd_product(int4(20));
|
|
float4 lo = simd_min(float4(20.0));
|
|
float4 hi = simd_max(float4(20.0));
|
|
int4 slo = simd_min(int4(20));
|
|
int4 shi = simd_max(int4(20));
|
|
uint4 ulo = simd_min(uint4(20u));
|
|
uint4 uhi = simd_max(uint4(20u));
|
|
uint4 anded = simd_and(ballot_value);
|
|
uint4 ored = simd_or(ballot_value);
|
|
uint4 xored = simd_xor(ballot_value);
|
|
added = simd_prefix_inclusive_sum(added);
|
|
iadded = simd_prefix_inclusive_sum(iadded);
|
|
multiplied = simd_prefix_inclusive_product(multiplied);
|
|
imultiplied = simd_prefix_inclusive_product(imultiplied);
|
|
added = simd_prefix_exclusive_sum(multiplied);
|
|
multiplied = simd_prefix_exclusive_product(multiplied);
|
|
iadded = simd_prefix_exclusive_sum(imultiplied);
|
|
imultiplied = simd_prefix_exclusive_product(imultiplied);
|
|
added = quad_sum(added);
|
|
multiplied = quad_product(multiplied);
|
|
iadded = quad_sum(iadded);
|
|
imultiplied = quad_product(imultiplied);
|
|
lo = quad_min(lo);
|
|
hi = quad_max(hi);
|
|
ulo = quad_min(ulo);
|
|
uhi = quad_max(uhi);
|
|
slo = quad_min(slo);
|
|
shi = quad_max(shi);
|
|
anded = quad_and(anded);
|
|
ored = quad_or(ored);
|
|
xored = quad_xor(xored);
|
|
float4 swap_horiz = quad_shuffle_xor(float4(20.0), 1u);
|
|
float4 swap_vertical = quad_shuffle_xor(float4(20.0), 2u);
|
|
float4 swap_diagonal = quad_shuffle_xor(float4(20.0), 3u);
|
|
float4 quad_broadcast0 = quad_broadcast(float4(20.0), 3u);
|
|
}
|
|
|