AVX指令集矩阵乘向量算法

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#include <stdio.h>#include <time.h>#include <x86intrin.h>void matmul_avx(const float *x, const float **w,float *y,const int col,const int row){    const int col_reduced_8 = col - col % 8;    float scratchpad[8];    __m256 op0, op1, tgt, tmp_vec;    for (int i = 0; i < row; i++) {        float res = 0;        tgt = _mm256_setzero_ps();        for (int j = 0; j < col_reduced_8; j += 8) {            op0 = __builtin_ia32_loadups256(&x[j]);            op1 = __builtin_ia32_loadups256(&w[i][j]);            tmp_vec = __builtin_ia32_mulps256(op0, op1);            tgt = __builtin_ia32_addps256(tmp_vec, tgt);        }        __builtin_ia32_storeups256(scratchpad, tgt);        for (int k = 0; k < 8; k++)            res += scratchpad[k];        for (int l = col_reduced_8; l < col; l++) {            res += w[i][l] * x[l];        }        y[i] = res;    }}int main() {    const int col = 2048, row = 512, num_mul = 10;    float **w;    float x[col];    float y[row];    float scratchpad[8];    w = (float **)malloc(sizeof(float*)*row);    for (int i = 0; i < row; i ++) { w[i] = (float *)malloc(sizeof(float) * col);    }    for (int i = 0; i < row; i++) {        for (int j = 0; j < col; j++) {            w[i][j] = (float) (rand() % 1000) / 800.0f;        }    }    for (int j = 0; j < col; j++) {        x[j] = (float) (rand() % 1000) / 800.0f;    }    clock_t t1, t2;// The original matrix multiplication version    t1 = clock();    for (int r = 0; r < num_mul; r++)        for (int j = 0; j < row; j++) {            float sum = 0;            float *wj = w[j];            for (int i = 0; i < col; i++)                sum += wj[i] * x[i];            y[j] = sum;        }    t2 = clock();    float diff = ((float) t2 - (float) t1) / (num_mul*CLOCKS_PER_SEC);    printf("\nTime taken: %f second.\n", diff);    for (int i = 0; i < row; i++) {        printf("%.4f, ", y[i]);        y[i]=0;    }    printf("\n");// The avx matrix multiplication version.    t1 = clock();    for (int r = 0; r < num_mul; r++)        matmul_avx(x,w,y,col,row);    t2 = clock();    diff = ((float) t2 - (float) t1) / (num_mul*CLOCKS_PER_SEC);    printf("\nTime taken: %f second.\n",diff);    for (int i = 0; i < row; i++) {        printf("%.4f, ", y[i]);    }    printf("\n");    }
运行方式：
gcc -o test test.c -mavx
./test
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