/*
* elementwise_kernels.hip
* ROCm/HIP kernels for memory-coalesced element-wise operations
* Optimized for AMD GPU memory hierarchy and wavefront execution
*/
#include <hip/hip_runtime.h>
// Memory-coalesced addition optimized for AMD wavefronts
__global__ void rocm_coalesced_add(float* a, float* b, float* output, int count) {
int gid = blockIdx.x * blockDim.x + threadIdx.x;
// Process multiple elements per thread for better memory utilization
const int elements_per_thread = 4;
int base_idx = gid * elements_per_thread;
// Use vectorized loads when possible (float4 for better memory bandwidth)
if (base_idx + 4 <= count && (base_idx % 4) == 0) {
float4 vec_a = reinterpret_cast<float4*>(a)[base_idx / 4];
float4 vec_b = reinterpret_cast<float4*>(b)[base_idx / 4];
float4 result;
result.x = vec_a.x + vec_b.x;
result.y = vec_a.y + vec_b.y;
result.z = vec_a.z + vec_b.z;
result.w = vec_a.w + vec_b.w;
reinterpret_cast<float4*>(output)[base_idx / 4] = result;
} else {
// Fallback to scalar operations for boundary elements
#pragma unroll
for (int i = 0; i < elements_per_thread; i++) {
int idx = base_idx + i;
if (idx < count) {
output[idx] = a[idx] + b[idx];
}
}
}
}
// Memory-coalesced multiplication
__global__ void rocm_coalesced_mul(float* a, float* b, float* output, int count) {
int gid = blockIdx.x * blockDim.x + threadIdx.x;
const int elements_per_thread = 4;
int base_idx = gid * elements_per_thread;
if (base_idx + 4 <= count && (base_idx % 4) == 0) {
float4 vec_a = reinterpret_cast<float4*>(a)[base_idx / 4];
float4 vec_b = reinterpret_cast<float4*>(b)[base_idx / 4];
float4 result;
result.x = vec_a.x * vec_b.x;
result.y = vec_a.y * vec_b.y;
result.z = vec_a.z * vec_b.z;
result.w = vec_a.w * vec_b.w;
reinterpret_cast<float4*>(output)[base_idx / 4] = result;
} else {
#pragma unroll
for (int i = 0; i < elements_per_thread; i++) {
int idx = base_idx + i;
if (idx < count) {
output[idx] = a[idx] * b[idx];
}
}
}
}
// Memory-coalesced subtraction
__global__ void rocm_coalesced_sub(float* a, float* b, float* output, int count) {
int gid = blockIdx.x * blockDim.x + threadIdx.x;
const int elements_per_thread = 4;
int base_idx = gid * elements_per_thread;
if (base_idx + 4 <= count && (base_idx % 4) == 0) {
float4 vec_a = reinterpret_cast<float4*>(a)[base_idx / 4];
float4 vec_b = reinterpret_cast<float4*>(b)[base_idx / 4];
float4 result;
result.x = vec_a.x - vec_b.x;
result.y = vec_a.y - vec_b.y;
result.z = vec_a.z - vec_b.z;
result.w = vec_a.w - vec_b.w;
reinterpret_cast<float4*>(output)[base_idx / 4] = result;
} else {
#pragma unroll
for (int i = 0; i < elements_per_thread; i++) {
int idx = base_idx + i;
if (idx < count) {
output[idx] = a[idx] - b[idx];
}
}
}
}
// Memory-coalesced division
__global__ void rocm_coalesced_div(float* a, float* b, float* output, int count) {
int gid = blockIdx.x * blockDim.x + threadIdx.x;
const int elements_per_thread = 4;
int base_idx = gid * elements_per_thread;
if (base_idx + 4 <= count && (base_idx % 4) == 0) {
float4 vec_a = reinterpret_cast<float4*>(a)[base_idx / 4];
float4 vec_b = reinterpret_cast<float4*>(b)[base_idx / 4];
float4 result;
result.x = vec_a.x / vec_b.x;
result.y = vec_a.y / vec_b.y;
result.z = vec_a.z / vec_b.z;
result.w = vec_a.w / vec_b.w;
reinterpret_cast<float4*>(output)[base_idx / 4] = result;
} else {
#pragma unroll
for (int i = 0; i < elements_per_thread; i++) {
int idx = base_idx + i;
if (idx < count) {
output[idx] = a[idx] / b[idx];
}
}
}
}
// RDNA-optimized element-wise operations using wave intrinsics
__global__ void rocm_rdna_optimized_add(float* a, float* b, float* output, int count) {
int gid = blockIdx.x * blockDim.x + threadIdx.x;
int wavefront_id = gid / 64; // RDNA wavefront size is 64
int lane_id = gid % 64;
// Use wave-level operations for better RDNA utilization
if (gid < count) {
float value_a = a[gid];
float value_b = b[gid];
float result = value_a + value_b;
// Use wave shuffle for better memory access patterns
// This is a simplified example - real implementation would use proper wave intrinsics
output[gid] = result;
}
}