ggml : add ggml_gelu_erf() (llama/13667)

* ggml : add ggml_gelu_na (not approximated)

* fix naming order

* rename na --> erf

* apply review suggesions

* revert naming order
This commit is contained in:
Xuan-Son Nguyen 2025-05-21 16:26:33 +02:00 committed by Georgi Gerganov
parent 131ee546ca
commit dd6ef64060
7 changed files with 213 additions and 2 deletions

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@ -528,14 +528,15 @@ extern "C" {
GGML_UNARY_OP_STEP,
GGML_UNARY_OP_TANH,
GGML_UNARY_OP_ELU,
GGML_UNARY_OP_RELU,
GGML_UNARY_OP_SIGMOID,
GGML_UNARY_OP_GELU,
GGML_UNARY_OP_GELU_ERF,
GGML_UNARY_OP_GELU_QUICK,
GGML_UNARY_OP_SILU,
GGML_UNARY_OP_HARDSWISH,
GGML_UNARY_OP_HARDSIGMOID,
GGML_UNARY_OP_EXP,
GGML_UNARY_OP_RELU,
GGML_UNARY_OP_COUNT,
};
@ -1024,6 +1025,16 @@ extern "C" {
struct ggml_context * ctx,
struct ggml_tensor * a);
// GELU using erf (error function) when possible
// some backends may fallback to approximation based on Abramowitz and Stegun formula
GGML_API struct ggml_tensor * ggml_gelu_erf(
struct ggml_context * ctx,
struct ggml_tensor * a);
GGML_API struct ggml_tensor * ggml_gelu_erf_inplace(
struct ggml_context * ctx,
struct ggml_tensor * a);
GGML_API struct ggml_tensor * ggml_gelu_quick(
struct ggml_context * ctx,
struct ggml_tensor * a);

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@ -2202,6 +2202,7 @@ static int ggml_get_n_tasks(struct ggml_tensor * node, int n_threads) {
} break;
case GGML_UNARY_OP_GELU:
case GGML_UNARY_OP_GELU_ERF:
case GGML_UNARY_OP_GELU_QUICK:
case GGML_UNARY_OP_SILU:
{

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@ -2691,6 +2691,109 @@ static void ggml_compute_forward_gelu(
}
}
// ggml_compute_forward_gelu_erf
static void ggml_compute_forward_gelu_erf_f32(
const ggml_compute_params * params,
ggml_tensor * dst) {
const ggml_tensor * src0 = dst->src[0];
assert(ggml_is_contiguous_1(src0));
assert(ggml_is_contiguous_1(dst));
assert(ggml_are_same_shape(src0, dst));
const int ith = params->ith;
const int nth = params->nth;
const int nc = src0->ne[0];
const int nr = ggml_nrows(src0);
// rows per thread
const int dr = (nr + nth - 1)/nth;
// row range for this thread
const int ir0 = dr*ith;
const int ir1 = MIN(ir0 + dr, nr);
for (int i1 = ir0; i1 < ir1; i1++) {
ggml_vec_gelu_erf_f32(nc,
(float *) ((char *) dst->data + i1*( dst->nb[1])),
(float *) ((char *) src0->data + i1*(src0->nb[1])));
#ifndef NDEBUG
for (int k = 0; k < nc; k++) {
const float x = ((float *) ((char *) dst->data + i1*( dst->nb[1])))[k];
GGML_UNUSED(x);
assert(!isnan(x));
assert(!isinf(x));
}
#endif
}
}
static void ggml_compute_forward_gelu_erf_f16(
const ggml_compute_params * params,
ggml_tensor * dst) {
const ggml_tensor * src0 = dst->src[0];
assert(ggml_is_contiguous_1(src0));
assert(ggml_is_contiguous_1(dst));
assert(ggml_are_same_shape(src0, dst));
const int ith = params->ith;
const int nth = params->nth;
const int nc = src0->ne[0];
const int nr = ggml_nrows(src0);
// rows per thread
const int dr = (nr + nth - 1)/nth;
// row range for this thread
const int ir0 = dr*ith;
const int ir1 = MIN(ir0 + dr, nr);
for (int i1 = ir0; i1 < ir1; i1++) {
ggml_vec_gelu_erf_f16(nc,
(ggml_fp16_t *) ((char *) dst->data + i1*( dst->nb[1])),
(ggml_fp16_t *) ((char *) src0->data + i1*(src0->nb[1])));
#ifndef NDEBUG
for (int k = 0; k < nc; k++) {
const ggml_fp16_t x = ((ggml_fp16_t *) ((char *) dst->data + i1*( dst->nb[1])))[k];
const float v = GGML_FP16_TO_FP32(x);
GGML_UNUSED(v);
assert(!isnan(v));
assert(!isinf(v));
}
#endif
}
}
static void ggml_compute_forward_gelu_erf(
const ggml_compute_params * params,
ggml_tensor * dst) {
const ggml_tensor * src0 = dst->src[0];
switch (src0->type) {
case GGML_TYPE_F32:
{
ggml_compute_forward_gelu_erf_f32(params, dst);
} break;
case GGML_TYPE_F16:
{
ggml_compute_forward_gelu_erf_f16(params, dst);
} break;
default:
{
GGML_ABORT("fatal error");
}
}
}
// ggml_compute_forward_gelu_quick
static void ggml_compute_forward_gelu_quick_f32(
@ -7749,6 +7852,10 @@ void ggml_compute_forward_unary(
{
ggml_compute_forward_gelu(params, dst);
} break;
case GGML_UNARY_OP_GELU_ERF:
{
ggml_compute_forward_gelu_erf(params, dst);
} break;
case GGML_UNARY_OP_GELU_QUICK:
{
ggml_compute_forward_gelu_quick(params, dst);

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@ -428,6 +428,7 @@ inline static void ggml_vec_exp_f16 (const int n, ggml_fp16_t * y, const ggml_fp
static const float GELU_COEF_A = 0.044715f;
static const float GELU_QUICK_COEF = -1.702f;
static const float SQRT_2_OVER_PI = 0.79788456080286535587989211986876f;
static const float SQRT_2_INV = 0.70710678118654752440084436210484f;
inline static float ggml_gelu_f32(float x) {
return 0.5f*x*(1.0f + tanhf(SQRT_2_OVER_PI*x*(1.0f + GELU_COEF_A*x*x)));
@ -440,6 +441,14 @@ inline static void ggml_vec_gelu_f16(const int n, ggml_fp16_t * y, const ggml_fp
}
}
inline static void ggml_vec_gelu_erf_f16(const int n, ggml_fp16_t * y, const ggml_fp16_t * x) {
for (int i = 0; i < n; ++i) {
float xi = GGML_FP16_TO_FP32(x[i]);
float res = 0.5f*xi*(1.0f + erff(xi*SQRT_2_INV));
y[i] = GGML_FP32_TO_FP16(res);
}
}
#ifdef GGML_GELU_FP16
inline static void ggml_vec_gelu_f32(const int n, float * y, const float * x) {
uint16_t t;
@ -463,6 +472,13 @@ inline static void ggml_vec_gelu_f32(const int n, float * y, const float * x) {
}
#endif
inline static void ggml_vec_gelu_erf_f32(const int n, float * y, const float * x) {
for (int i = 0; i < n; ++i) {
float xi = x[i];
y[i] = 0.5f*xi*(1.0f + erff(xi*SQRT_2_INV));
}
}
inline static float ggml_gelu_quick_f32(float x) {
return x*(1.0f/(1.0f+expf(GELU_QUICK_COEF*x)));
}

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@ -149,6 +149,8 @@ enum ggml_metal_kernel_type {
GGML_METAL_KERNEL_TYPE_SIGMOID,
GGML_METAL_KERNEL_TYPE_GELU,
GGML_METAL_KERNEL_TYPE_GELU_4,
GGML_METAL_KERNEL_TYPE_GELU_ERF,
GGML_METAL_KERNEL_TYPE_GELU_ERF_4,
GGML_METAL_KERNEL_TYPE_GELU_QUICK,
GGML_METAL_KERNEL_TYPE_GELU_QUICK_4,
GGML_METAL_KERNEL_TYPE_SILU,
@ -1103,6 +1105,8 @@ static struct ggml_backend_metal_context * ggml_metal_init(ggml_backend_dev_t de
GGML_METAL_ADD_KERNEL(GGML_METAL_KERNEL_TYPE_SIGMOID, sigmoid, true);
GGML_METAL_ADD_KERNEL(GGML_METAL_KERNEL_TYPE_GELU, gelu, true);
GGML_METAL_ADD_KERNEL(GGML_METAL_KERNEL_TYPE_GELU_4, gelu_4, true);
GGML_METAL_ADD_KERNEL(GGML_METAL_KERNEL_TYPE_GELU_ERF, gelu_erf, true);
GGML_METAL_ADD_KERNEL(GGML_METAL_KERNEL_TYPE_GELU_ERF_4, gelu_erf_4, true);
GGML_METAL_ADD_KERNEL(GGML_METAL_KERNEL_TYPE_GELU_QUICK, gelu_quick, true);
GGML_METAL_ADD_KERNEL(GGML_METAL_KERNEL_TYPE_GELU_QUICK_4, gelu_quick_4, true);
GGML_METAL_ADD_KERNEL(GGML_METAL_KERNEL_TYPE_SILU, silu, true);
@ -1613,6 +1617,7 @@ static bool ggml_metal_supports_op(const struct ggml_backend_metal_device_contex
case GGML_UNARY_OP_RELU:
case GGML_UNARY_OP_SIGMOID:
case GGML_UNARY_OP_GELU:
case GGML_UNARY_OP_GELU_ERF:
case GGML_UNARY_OP_GELU_QUICK:
case GGML_UNARY_OP_SILU:
case GGML_UNARY_OP_ELU:
@ -2251,6 +2256,25 @@ static bool ggml_metal_encode_node(
[encoder dispatchThreadgroups:MTLSizeMake(n, 1, 1) threadsPerThreadgroup:MTLSizeMake(1, 1, 1)];
} break;
case GGML_UNARY_OP_GELU_ERF:
{
int64_t n = ggml_nelements(dst);
id<MTLComputePipelineState> pipeline = nil;
if (n % 4 == 0) {
pipeline = ctx->kernels[GGML_METAL_KERNEL_TYPE_GELU_ERF_4].pipeline;
n /= 4;
} else {
pipeline = ctx->kernels[GGML_METAL_KERNEL_TYPE_GELU_ERF].pipeline;
}
[encoder setComputePipelineState:pipeline];
[encoder setBuffer:id_src0 offset:offs_src0 atIndex:0];
[encoder setBuffer:id_dst offset:offs_dst atIndex:1];
[encoder dispatchThreadgroups:MTLSizeMake(n, 1, 1) threadsPerThreadgroup:MTLSizeMake(1, 1, 1)];
} break;
case GGML_UNARY_OP_GELU_QUICK:
{
int64_t n = ggml_nelements(dst);

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@ -856,6 +856,7 @@ kernel void kernel_tanh(
constant float GELU_COEF_A = 0.044715f;
constant float GELU_QUICK_COEF = -1.702f;
constant float SQRT_2_OVER_PI = 0.79788456080286535587989211986876f;
constant float SQRT_2_INV = 0.70710678118654752440084436210484f;
kernel void kernel_gelu(
device const float * src0,
@ -897,6 +898,42 @@ kernel void kernel_gelu_quick_4(
dst[tpig] = x*(1.0f/(1.0f+exp(GELU_QUICK_COEF*x)));
}
// based on Abramowitz and Stegun formula 7.1.26 or similar Hastings' approximation
// ref: https://www.johndcook.com/blog/python_erf/
constant float p_erf = 0.3275911f;
constant float a1_erf = 0.254829592f;
constant float a2_erf = -0.284496736f;
constant float a3_erf = 1.421413741f;
constant float a4_erf = -1.453152027f;
constant float a5_erf = 1.061405429f;
template<typename T>
T erf_approx(T x) {
T sign_x = sign(x);
x = fabs(x);
T t = 1.0f / (1.0f + p_erf * x);
T y = 1.0f - (((((a5_erf * t + a4_erf) * t) + a3_erf) * t + a2_erf) * t + a1_erf) * t * exp(-x * x);
return sign_x * y;
}
kernel void kernel_gelu_erf(
device const float * src0,
device float * dst,
uint tpig[[thread_position_in_grid]]) {
device const float & x = src0[tpig];
dst[tpig] = 0.5f*x*(1.0f+erf_approx<float>(x*SQRT_2_INV));
}
kernel void kernel_gelu_erf_4(
device const float4 * src0,
device float4 * dst,
uint tpig[[thread_position_in_grid]]) {
device const float4 & x = src0[tpig];
dst[tpig] = 0.5f*x*(1.0f+erf_approx<float4>(x*SQRT_2_INV));
}
kernel void kernel_silu(
device const float * src0,
device float * dst,

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@ -1099,9 +1099,10 @@ static const char * GGML_UNARY_OP_NAME[GGML_UNARY_OP_COUNT] = {
"HARDSWISH",
"HARDSIGMOID",
"EXP",
"GELU_ERF",
};
static_assert(GGML_UNARY_OP_COUNT == 14, "GGML_UNARY_OP_COUNT != 14");
static_assert(GGML_UNARY_OP_COUNT == 15, "GGML_UNARY_OP_COUNT != 15");
static_assert(sizeof(struct ggml_object)%GGML_MEM_ALIGN == 0, "ggml_object size must be a multiple of GGML_MEM_ALIGN");
@ -2501,6 +2502,20 @@ struct ggml_tensor * ggml_gelu_inplace(
return ggml_unary_inplace(ctx, a, GGML_UNARY_OP_GELU);
}
// ggml_gelu_erf
struct ggml_tensor * ggml_gelu_erf(
struct ggml_context * ctx,
struct ggml_tensor * a) {
return ggml_unary(ctx, a, GGML_UNARY_OP_GELU_ERF);
}
struct ggml_tensor * ggml_gelu_erf_inplace(
struct ggml_context * ctx,
struct ggml_tensor * a) {
return ggml_unary_inplace(ctx, a, GGML_UNARY_OP_GELU_ERF);
}
// ggml_gelu_quick
struct ggml_tensor * ggml_gelu_quick(