fix gemm Sgemm_omp when bias = nullptr

src/operators/math/gemm.cpp

@@ -3307,9 +3307,14 @@ void Gemm::Sgemm_omp(int m, int n, int k, float alpha, const float *A, int lda,
       float *local_A = packedA + MC * KC * local_threads;
       float *local_C = packedC + MC * NC * local_threads;
       (*this.*procPackA)(mc, KC, mc % MR, &A(i, 0), lda, local_A);
+      if (bias == nullptr) {
+        InnerKernelWithBias(mc, n, alpha, local_A, packedB, beta, local_C,
+                            &C(i, 0), ldc, relu, nullptr);
+      } else {
         InnerKernelWithBias(mc, n, alpha, local_A, packedB, beta, local_C,
                             &C(i, 0), ldc, relu, bias + i);
       }
+    }
   } else {
 #pragma omp parallel for
     for (int j = 0; j < n; j += NC) {