fixed issues with matmul fp16

Author: cjm715

onnxruntime/core/providers/cpu/math/matmul.cc

@@ -136,7 +136,12 @@ Status MatMul<T>::Compute(OpKernelContext* ctx) const {
     // be filled out with zeros.
     EigenMatrixMapRowMajor<T> dest(y->MutableData<T>(),
                                    narrow<Eigen::Index>(helper.M()), narrow<Eigen::Index>(helper.N()));
-    dest.setZero();
+    if constexpr (std::is_same<T, MLFloat16>::value) {
+      dest.setConstant(MLFloat16(0.0f));
+    } else {
+      dest.setZero();
+    }
+
     return Status::OK();
   }
 

onnxruntime/test/providers/cpu/math/matmul_test.cc

@@ -311,7 +311,7 @@ TEST(MathOpTest, MatMul_Float16) {
   run_test(true);
   run_test(false);
 }
-// #endif
+#endif
 
 #if defined(USE_CUDA) || defined(USE_ROCM) || defined(USE_DNNL)
 TEST(MathOpTest, MatMul_bfloat16) {