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Nov 8, 2024
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8-bit packing support #1248

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160 changes: 117 additions & 43 deletions torchao/experimental/kernels/cpu/aarch64/bitpacking/bitpack.h
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Original file line number Diff line number Diff line change
Expand Up @@ -77,13 +77,18 @@ TORCHAO_ALWAYS_INLINE inline void vec_pack_32_lowbit_values(
uint8_t* packed,
const int8x16_t& unpacked0,
const int8x16_t& unpacked1) {
static_assert(nbit < 8);
static_assert(nbit < 9);
static_assert(nbit >= 1);

// Shift unpacked values to nonnegative range
int8x16_t shift = vdupq_n_s8(1 << (nbit - 1));
uint8x16_t shifted0 = vreinterpretq_u8_s8(vaddq_s8(unpacked0, shift));
uint8x16_t shifted1 = vreinterpretq_u8_s8(vaddq_s8(unpacked1, shift));
// Shift unpacked values to nonnegative range for quantization of 1-7 bits
// No shifting is needed for 8-bit packing
uint8x16_t shifted0;
uint8x16_t shifted1;
if constexpr (nbit < 8) {
int8x16_t shift = vdupq_n_s8(1 << (nbit - 1));
shifted0 = vreinterpretq_u8_s8(vaddq_s8(unpacked0, shift));
shifted1 = vreinterpretq_u8_s8(vaddq_s8(unpacked1, shift));
}

switch (nbit) {
case 1:
Expand Down Expand Up @@ -151,6 +156,10 @@ TORCHAO_ALWAYS_INLINE inline void vec_pack_32_lowbit_values(
torchao::bitpacking::internal::pack_8_uint7_values(packed + 14, buffer7 + 16);
torchao::bitpacking::internal::pack_8_uint7_values(packed + 21, buffer7 + 24);
break;
case 8:
vst1q_u8(packed, vreinterpretq_u8_s8(unpacked0));
vst1q_u8(packed + 16, vreinterpretq_u8_s8(unpacked1));
break;
default:
assert(false);
}
Expand All @@ -161,7 +170,7 @@ TORCHAO_ALWAYS_INLINE inline void vec_unpack_32_lowbit_values(
int8x16_t& unpacked0,
int8x16_t& unpacked1,
const uint8_t* packed) {
static_assert(nbit < 8);
static_assert(nbit < 9);
static_assert(nbit >= 1);

uint8x16_t shifted0;
Expand Down Expand Up @@ -234,14 +243,21 @@ TORCHAO_ALWAYS_INLINE inline void vec_unpack_32_lowbit_values(
shifted0 = vld1q_u8(buffer7);
shifted1 = vld1q_u8(buffer7 + 16);
break;
case 8:
unpacked0 = vreinterpretq_s8_u8(vld1q_u8(packed));
unpacked1 = vreinterpretq_s8_u8(vld1q_u8(packed + 16));
break;
default:
assert(false);
}

// unshift to move unpacked values to full range
int8x16_t unshift = vdupq_n_s8(-(1 << (nbit - 1)));
unpacked0 = vaddq_s8(vreinterpretq_s8_u8(shifted0), unshift);
unpacked1 = vaddq_s8(vreinterpretq_s8_u8(shifted1), unshift);
// no shifting is needed for 8-bit packing
if constexpr (nbit < 8) {
int8x16_t unshift = vdupq_n_s8(-(1 << (nbit - 1)));
unpacked0 = vaddq_s8(vreinterpretq_s8_u8(shifted0), unshift);
unpacked1 = vaddq_s8(vreinterpretq_s8_u8(shifted1), unshift);
}
}

template <int nbit>
Expand All @@ -251,15 +267,23 @@ TORCHAO_ALWAYS_INLINE inline void vec_pack_64_lowbit_values(
const int8x16_t& unpacked1,
const int8x16_t& unpacked2,
const int8x16_t& unpacked3) {
static_assert(nbit < 8);
static_assert(nbit < 9);
static_assert(nbit >= 1);

// Shift unpacked values to nonnegative range
int8x16_t shift = vdupq_n_s8(1 << (nbit - 1));
uint8x16_t shifted0 = vreinterpretq_u8_s8(vaddq_s8(unpacked0, shift));
uint8x16_t shifted1 = vreinterpretq_u8_s8(vaddq_s8(unpacked1, shift));
uint8x16_t shifted2 = vreinterpretq_u8_s8(vaddq_s8(unpacked2, shift));
uint8x16_t shifted3 = vreinterpretq_u8_s8(vaddq_s8(unpacked3, shift));
// Shift unpacked values to nonnegative range for quantization of 1-7 bits
// No shifting is needed for 8-bit packing
uint8x16_t shifted0;
uint8x16_t shifted1;
uint8x16_t shifted2;
uint8x16_t shifted3;
if constexpr (nbit < 8) {
int8x16_t shift = vdupq_n_s8(1 << (nbit - 1));
shifted0 = vreinterpretq_u8_s8(vaddq_s8(unpacked0, shift));
shifted1 = vreinterpretq_u8_s8(vaddq_s8(unpacked1, shift));
shifted2 = vreinterpretq_u8_s8(vaddq_s8(unpacked2, shift));
shifted3 = vreinterpretq_u8_s8(vaddq_s8(unpacked3, shift));
}


switch (nbit) {
case 1:
Expand Down Expand Up @@ -292,6 +316,12 @@ TORCHAO_ALWAYS_INLINE inline void vec_pack_64_lowbit_values(
torchao::bitpacking::internal::vec_pack_64_uint7_values(
packed, shifted0, shifted1, shifted2, shifted3);
break;
case 8:
vst1q_u8(packed, vreinterpretq_u8_s8(unpacked0));
vst1q_u8(packed + 16, vreinterpretq_u8_s8(unpacked1));
vst1q_u8(packed + 32, vreinterpretq_u8_s8(unpacked2));
vst1q_u8(packed + 48, vreinterpretq_u8_s8(unpacked3));
break;
default:
assert(false);
}
Expand All @@ -304,7 +334,7 @@ TORCHAO_ALWAYS_INLINE inline void vec_unpack_64_lowbit_values(
int8x16_t& unpacked2,
int8x16_t& unpacked3,
const uint8_t* packed) {
static_assert(nbit < 8);
static_assert(nbit < 9);
static_assert(nbit >= 1);

uint8x16_t shifted0;
Expand Down Expand Up @@ -343,16 +373,25 @@ TORCHAO_ALWAYS_INLINE inline void vec_unpack_64_lowbit_values(
torchao::bitpacking::internal::vec_unpack_64_uint7_values(
shifted0, shifted1, shifted2, shifted3, packed);
break;
case 8:
unpacked0 = vreinterpretq_s8_u8(vld1q_u8(packed));
unpacked1 = vreinterpretq_s8_u8(vld1q_u8(packed + 16));
unpacked2 = vreinterpretq_s8_u8(vld1q_u8(packed + 32));
unpacked3 = vreinterpretq_s8_u8(vld1q_u8(packed + 48));
break;
default:
assert(false);
}

// unshift to move unpacked values to full range
int8x16_t unshift = vdupq_n_s8(-(1 << (nbit - 1)));
unpacked0 = vaddq_s8(vreinterpretq_s8_u8(shifted0), unshift);
unpacked1 = vaddq_s8(vreinterpretq_s8_u8(shifted1), unshift);
unpacked2 = vaddq_s8(vreinterpretq_s8_u8(shifted2), unshift);
unpacked3 = vaddq_s8(vreinterpretq_s8_u8(shifted3), unshift);
// no shifting is needed for 8-bit packing
if constexpr (nbit < 8) {
int8x16_t unshift = vdupq_n_s8(-(1 << (nbit - 1)));
unpacked0 = vaddq_s8(vreinterpretq_s8_u8(shifted0), unshift);
unpacked1 = vaddq_s8(vreinterpretq_s8_u8(shifted1), unshift);
unpacked2 = vaddq_s8(vreinterpretq_s8_u8(shifted2), unshift);
unpacked3 = vaddq_s8(vreinterpretq_s8_u8(shifted3), unshift);
}
}

template <int nbit>
Expand All @@ -366,19 +405,31 @@ TORCHAO_ALWAYS_INLINE inline void vec_pack_128_lowbit_values(
const int8x16_t& unpacked5,
const int8x16_t& unpacked6,
const int8x16_t& unpacked7) {
static_assert(nbit < 8);
static_assert(nbit < 9);
static_assert(nbit >= 1);

// Shift unpacked values to nonnegative range
int8x16_t shift = vdupq_n_s8(1 << (nbit - 1));
uint8x16_t shifted0 = vreinterpretq_u8_s8(vaddq_s8(unpacked0, shift));
uint8x16_t shifted1 = vreinterpretq_u8_s8(vaddq_s8(unpacked1, shift));
uint8x16_t shifted2 = vreinterpretq_u8_s8(vaddq_s8(unpacked2, shift));
uint8x16_t shifted3 = vreinterpretq_u8_s8(vaddq_s8(unpacked3, shift));
uint8x16_t shifted4 = vreinterpretq_u8_s8(vaddq_s8(unpacked4, shift));
uint8x16_t shifted5 = vreinterpretq_u8_s8(vaddq_s8(unpacked5, shift));
uint8x16_t shifted6 = vreinterpretq_u8_s8(vaddq_s8(unpacked6, shift));
uint8x16_t shifted7 = vreinterpretq_u8_s8(vaddq_s8(unpacked7, shift));
// Shift unpacked values to nonnegative range for quantization of 1-7 bits
// No shifting is needed for 8-bit packing
uint8x16_t shifted0;
uint8x16_t shifted1;
uint8x16_t shifted2;
uint8x16_t shifted3;
uint8x16_t shifted4;
uint8x16_t shifted5;
uint8x16_t shifted6;
uint8x16_t shifted7;
if constexpr (nbit < 8) {
int8x16_t shift = vdupq_n_s8(1 << (nbit - 1));
shifted0 = vreinterpretq_u8_s8(vaddq_s8(unpacked0, shift));
shifted1 = vreinterpretq_u8_s8(vaddq_s8(unpacked1, shift));
shifted2 = vreinterpretq_u8_s8(vaddq_s8(unpacked2, shift));
shifted3 = vreinterpretq_u8_s8(vaddq_s8(unpacked3, shift));
shifted4 = vreinterpretq_u8_s8(vaddq_s8(unpacked4, shift));
shifted5 = vreinterpretq_u8_s8(vaddq_s8(unpacked5, shift));
shifted6 = vreinterpretq_u8_s8(vaddq_s8(unpacked6, shift));
shifted7 = vreinterpretq_u8_s8(vaddq_s8(unpacked7, shift));
}


switch (nbit) {
case 1:
Expand Down Expand Up @@ -451,6 +502,16 @@ TORCHAO_ALWAYS_INLINE inline void vec_pack_128_lowbit_values(
shifted6,
shifted7);
break;
case 8:
vst1q_u8(packed, vreinterpretq_u8_s8(unpacked0));
vst1q_u8(packed + 16, vreinterpretq_u8_s8(unpacked1));
vst1q_u8(packed + 32, vreinterpretq_u8_s8(unpacked2));
vst1q_u8(packed + 48, vreinterpretq_u8_s8(unpacked3));
vst1q_u8(packed + 64, vreinterpretq_u8_s8(unpacked4));
vst1q_u8(packed + 80, vreinterpretq_u8_s8(unpacked5));
vst1q_u8(packed + 96, vreinterpretq_u8_s8(unpacked6));
vst1q_u8(packed + 112, vreinterpretq_u8_s8(unpacked7));
break;
default:
assert(false);
}
Expand All @@ -467,7 +528,7 @@ TORCHAO_ALWAYS_INLINE inline void vec_unpack_128_lowbit_values(
int8x16_t& unpacked6,
int8x16_t& unpacked7,
const uint8_t* packed) {
static_assert(nbit < 8);
static_assert(nbit < 9);
static_assert(nbit >= 1);

uint8x16_t shifted0;
Expand Down Expand Up @@ -550,20 +611,33 @@ TORCHAO_ALWAYS_INLINE inline void vec_unpack_128_lowbit_values(
shifted7,
packed);
break;
case 8:
unpacked0 = vreinterpretq_s8_u8(vld1q_u8(packed));
unpacked1 = vreinterpretq_s8_u8(vld1q_u8(packed + 16));
unpacked2 = vreinterpretq_s8_u8(vld1q_u8(packed + 32));
unpacked3 = vreinterpretq_s8_u8(vld1q_u8(packed + 48));
unpacked4 = vreinterpretq_s8_u8(vld1q_u8(packed + 64));
unpacked5 = vreinterpretq_s8_u8(vld1q_u8(packed + 80));
unpacked6 = vreinterpretq_s8_u8(vld1q_u8(packed + 96));
unpacked7 = vreinterpretq_s8_u8(vld1q_u8(packed + 112));
break;
default:
assert(false);
}

// unshift to move unpacked values to full range
int8x16_t unshift = vdupq_n_s8(-(1 << (nbit - 1)));
unpacked0 = vaddq_s8(vreinterpretq_s8_u8(shifted0), unshift);
unpacked1 = vaddq_s8(vreinterpretq_s8_u8(shifted1), unshift);
unpacked2 = vaddq_s8(vreinterpretq_s8_u8(shifted2), unshift);
unpacked3 = vaddq_s8(vreinterpretq_s8_u8(shifted3), unshift);
unpacked4 = vaddq_s8(vreinterpretq_s8_u8(shifted4), unshift);
unpacked5 = vaddq_s8(vreinterpretq_s8_u8(shifted5), unshift);
unpacked6 = vaddq_s8(vreinterpretq_s8_u8(shifted6), unshift);
unpacked7 = vaddq_s8(vreinterpretq_s8_u8(shifted7), unshift);
// no shifting is needed for 8-bit packing
if constexpr (nbit < 8) {
int8x16_t unshift = vdupq_n_s8(-(1 << (nbit - 1)));
unpacked0 = vaddq_s8(vreinterpretq_s8_u8(shifted0), unshift);
unpacked1 = vaddq_s8(vreinterpretq_s8_u8(shifted1), unshift);
unpacked2 = vaddq_s8(vreinterpretq_s8_u8(shifted2), unshift);
unpacked3 = vaddq_s8(vreinterpretq_s8_u8(shifted3), unshift);
unpacked4 = vaddq_s8(vreinterpretq_s8_u8(shifted4), unshift);
unpacked5 = vaddq_s8(vreinterpretq_s8_u8(shifted5), unshift);
unpacked6 = vaddq_s8(vreinterpretq_s8_u8(shifted6), unshift);
unpacked7 = vaddq_s8(vreinterpretq_s8_u8(shifted7), unshift);
}
}

} // namespace bitpacking
Expand Down
33 changes: 6 additions & 27 deletions torchao/experimental/kernels/cpu/aarch64/tests/test_bitpacking.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -674,15 +674,7 @@ template <int nbit>
void test_bitpacking_32_lowbit_values() {
int unpacked_bytes = 32;
int packed_bytes = unpacked_bytes * nbit / 8;
auto input_shifted = torchao::get_random_lowbit_vector(unpacked_bytes, nbit);
std::vector<int8_t> input(unpacked_bytes, 0);
int8_t low = -(1 << (nbit - 1));
int8_t high = (1 << (nbit - 1));
for (int i = 0; i < unpacked_bytes; ++i) {
input[i] = (int8_t)(input_shifted[i]) + low;
assert(input[i] >= low);
assert(input[i] <= high);
}
auto input = torchao::get_random_signed_lowbit_vector(unpacked_bytes, nbit);
std::vector<uint8_t> packed(packed_bytes, 0);

int8x16_t input0;
Expand All @@ -706,15 +698,7 @@ template <int nbit>
void test_bitpacking_64_lowbit_values() {
int unpacked_bytes = 64;
int packed_bytes = unpacked_bytes * nbit / 8;
auto input_shifted = torchao::get_random_lowbit_vector(unpacked_bytes, nbit);
std::vector<int8_t> input(unpacked_bytes, 0);
int8_t low = -(1 << (nbit - 1));
int8_t high = (1 << (nbit - 1));
for (int i = 0; i < unpacked_bytes; ++i) {
input[i] = (int8_t)(input_shifted[i]) + low;
assert(input[i] >= low);
assert(input[i] <= high);
}
auto input = torchao::get_random_signed_lowbit_vector(unpacked_bytes, nbit);
std::vector<uint8_t> packed(packed_bytes, 0);

int8x16_t input0;
Expand Down Expand Up @@ -746,15 +730,7 @@ template <int nbit>
void test_bitpacking_128_lowbit_values() {
int unpacked_bytes = 128;
int packed_bytes = unpacked_bytes * nbit / 8;
auto input_shifted = torchao::get_random_lowbit_vector(unpacked_bytes, nbit);
std::vector<int8_t> input(unpacked_bytes, 0);
int8_t low = -(1 << (nbit - 1));
int8_t high = (1 << (nbit - 1));
for (int i = 0; i < unpacked_bytes; ++i) {
input[i] = (int8_t)(input_shifted[i]) + low;
assert(input[i] >= low);
assert(input[i] <= high);
}
auto input = torchao::get_random_signed_lowbit_vector(unpacked_bytes, nbit);
std::vector<uint8_t> packed(packed_bytes, 0);

int8x16_t input0;
Expand Down Expand Up @@ -836,6 +812,7 @@ TEST_BITPACKING_32_LOWBIT_VALUES(4);
TEST_BITPACKING_32_LOWBIT_VALUES(5);
TEST_BITPACKING_32_LOWBIT_VALUES(6);
TEST_BITPACKING_32_LOWBIT_VALUES(7);
TEST_BITPACKING_32_LOWBIT_VALUES(8);

TEST_BITPACKING_64_LOWBIT_VALUES(1);
TEST_BITPACKING_64_LOWBIT_VALUES(2);
Expand All @@ -844,6 +821,7 @@ TEST_BITPACKING_64_LOWBIT_VALUES(4);
TEST_BITPACKING_64_LOWBIT_VALUES(5);
TEST_BITPACKING_64_LOWBIT_VALUES(6);
TEST_BITPACKING_64_LOWBIT_VALUES(7);
TEST_BITPACKING_64_LOWBIT_VALUES(8);

TEST_BITPACKING_128_LOWBIT_VALUES(1);
TEST_BITPACKING_128_LOWBIT_VALUES(2);
Expand All @@ -852,5 +830,6 @@ TEST_BITPACKING_128_LOWBIT_VALUES(4);
TEST_BITPACKING_128_LOWBIT_VALUES(5);
TEST_BITPACKING_128_LOWBIT_VALUES(6);
TEST_BITPACKING_128_LOWBIT_VALUES(7);
TEST_BITPACKING_128_LOWBIT_VALUES(8);

#endif // defined(__aarch64__) || defined(__ARM_NEON)
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