fix gemm function sgemv_mx1 (#1743)

src/operators/math/gemm/gemm_kernel.h

@@ -407,14 +407,10 @@ void sgemv_notrans_mx1(const int M, const int N, const float alpha,
       _b = vandq_f32_u32(_b, vmask);
       _sum0 = vmlaq_f32(_sum0, _r0, _b);
     }
-    _sum0 = vpaddq_f32(_sum0, _sum0);
-    _sum0 = vmulq_f32(_sum0, _valpha);
-    if (beta != 0.f) {
-      float32x4_t _sum2 = vmulq_n_f32(vld1q_f32(output), beta);
-      _sum0 = vpaddq_f32(_sum0, _sum2);
-    }
-    // restore
-    *output = vgetq_lane_f32(_sum0, 0) + vgetq_lane_f32(_sum0, 1);
+    float32x2_t _ss = vadd_f32(vget_low_f32(_sum0), vget_high_f32(_sum0));
+    float32x2_t _sss2 = vpadd_f32(_ss, _ss);
+    *output =
+        vget_lane_f32(_sss2, 0) * vgetq_lane_f32(_valpha, 0) + beta * (*output);
   }
 }
 
@@ -536,7 +532,7 @@ void sgemv_trans_mx1(const int M, const int N, const float alpha,
   } else {  // beta != 0.f
     float32x4_t _vbeta = vdupq_n_f32(beta);
     #pragma omp parallel for
-    for (int m = 0; m < M; m += 4) {
+    for (int m = 0; m < M - 3; m += 4) {
       float32x4_t _sum0 = vld1q_f32(buf_c + m);
       for (int tid = 1; tid < threads_num; ++tid) {
         _sum0 += vld1q_f32(buf_c + tid * M + m);
@@ -545,7 +541,7 @@ void sgemv_trans_mx1(const int M, const int N, const float alpha,
       vst1q_f32(C + m, _sum0 * _valpha + _vbeta * _vc);
     }
 
-    for (int m = (M & 0xfffffffc); m < M - 3; ++m) {
+    for (int m = (M & 0xfffffffc); m < M; ++m) {
       float _sum0 = *(buf_c + m);
       for (int tid = 1; tid < threads_num; ++tid) {
         _sum0 += *(buf_c + tid * M + m);