gelu_kernels_bf16.c File Reference

GELU activation kernels for BF16 tensors. More...

#include <stdint.h>
#include <string.h>
#include "bf16_utils.h"
#include "ckernel_engine.h"

Go to the source code of this file.

Functions
void	gelu_backward_exact_bf16 (const uint16_t *input, const uint16_t *d_output, uint16_t *d_input, size_t n, float *scratch_input, float *scratch_d_output, float *scratch_d_input)
void	gelu_backward_fast_bf16 (const uint16_t *input, const uint16_t *d_output, uint16_t *d_input, size_t n, float *scratch_input, float *scratch_d_output, float *scratch_d_input)
void	gelu_fast_inplace_bf16 (uint16_t *data, size_t n, float *scratch)

Detailed Description

GELU activation kernels for BF16 tensors.

CK-ENGINE KERNEL RULES:

1. NO malloc/free - memory via bump allocator, pointers passed in
2. NO OpenMP - parallelization at orchestrator/codegen layer
3. API must define: inputs, outputs, workspace, and memory layouts
4. Pure computation - deterministic, no side effects

After changes: make test && make llamacpp-parity-full

GELU: y = x * 0.5 * (1 + erf(x / sqrt(2)))

Definition in file gelu_kernels_bf16.c.

Function Documentation

gelu_backward_exact_bf16()

void gelu_backward_exact_bf16	(	const uint16_t *	input,
		const uint16_t *	d_output,
		uint16_t *	d_input,
		size_t	n,
		float *	scratch_input,
		float *	scratch_d_output,
		float *	scratch_d_input
	)

Definition at line 46 of file gelu_kernels_bf16.c.

{
    if (!scratch_input || !scratch_d_output || !scratch_d_input) return;
 
    bf16_tensor_to_float(input, scratch_input, n);
    bf16_tensor_to_float(d_output, scratch_d_output, n);
 
    // Use scalar exact version to avoid fast tanh approximation error
    // accumulating with BF16 precision loss.
    gelu_backward_scalar(scratch_input, scratch_d_output, scratch_d_input, n);
 
    float_tensor_to_bf16(scratch_d_input, d_input, n);
}

References bf16_tensor_to_float(), float_tensor_to_bf16(), and gelu_backward_scalar().

gelu_backward_fast_bf16()

void gelu_backward_fast_bf16	(	const uint16_t *	input,
		const uint16_t *	d_output,
		uint16_t *	d_input,
		size_t	n,
		float *	scratch_input,
		float *	scratch_d_output,
		float *	scratch_d_input
	)

Definition at line 69 of file gelu_kernels_bf16.c.

{
    if (!scratch_input || !scratch_d_output || !scratch_d_input) return;
 
    bf16_tensor_to_float(input, scratch_input, n);
    bf16_tensor_to_float(d_output, scratch_d_output, n);
 
    gelu_backward_fast(scratch_input, scratch_d_output, scratch_d_input, n);
 
    float_tensor_to_bf16(scratch_d_input, d_input, n);
}

References bf16_tensor_to_float(), float_tensor_to_bf16(), and gelu_backward_fast().

gelu_fast_inplace_bf16()

void gelu_fast_inplace_bf16	(	uint16_t *	data,
		size_t	n,
		float *	scratch
	)

Definition at line 31 of file gelu_kernels_bf16.c.

{
    if (!scratch) return;
 
    bf16_tensor_to_float(data, scratch, n);
    // Use exact version to avoid fast tanh approximation error accumulating
    // with BF16 precision loss. Conversion overhead dominates anyway.
    gelu_exact_inplace(scratch, n);
    float_tensor_to_bf16(scratch, data, n);
}

References bf16_tensor_to_float(), float_tensor_to_bf16(), and gelu_exact_inplace().