Remove redundant fill in SPMM kernel (#3166)

* remove redundant fill

* trigger ci

Author: VoVAllen

src/array/cpu/spmm.cc

@@ -22,8 +22,6 @@ void SpMMCsr(const std::string& op, const std::string& reduce,
   if (reduce == "sum") {
     SWITCH_BITS(bits, DType, {
       SWITCH_OP(op, Op, {
-        DType *out_off = out.Ptr<DType>();
-        std::fill(out_off, out_off + csr.num_rows * dim, 0);
         cpu::SpMMSumCsr<IdType, DType, Op>(bcast, csr, ufeat, efeat, out);
       });
     });
@@ -33,8 +31,6 @@ void SpMMCsr(const std::string& op, const std::string& reduce,
         DType *out_off = out.Ptr<DType>();
         IdType* argX = Op::use_lhs ? static_cast<IdType*>(out_aux[0]->data) : nullptr;
         IdType* argW = Op::use_rhs ? static_cast<IdType*>(out_aux[1]->data) : nullptr;
-        if (Op::use_lhs) std::fill(argX, argX + csr.num_rows * dim, 0);
-        if (Op::use_rhs) std::fill(argW, argW + csr.num_rows * dim, 0);
         if (reduce == "max") {
           std::fill(out_off, out_off + csr.num_rows * dim, cpu::op::Max<DType>::zero);
           cpu::SpMMCmpCsr<IdType, DType, Op, cpu::op::Max<DType>>(
@@ -66,11 +62,6 @@ void SpMMCsrHetero(const std::string& op, const std::string& reduce,
   if (reduce == "sum") {
     SWITCH_BITS(bits, DType, {
       SWITCH_OP(op, Op, {
-        // TODO(Israt): Ideally the for loop should go over num_ntypes
-        for (dgl_type_t etype = 0; etype < ufeat_node_tids.size(); ++etype) {
-          DType *out_off = vec_out[out_node_tids[etype]].Ptr<DType>();
-          std::fill(out_off, out_off + vec_csr[etype].num_rows * dim, 0);
-        }
         /* Call  SpMM for each relation type */
         for (dgl_type_t etype = 0; etype < ufeat_node_tids.size(); ++etype) {
           const dgl_type_t src_id = ufeat_node_tids[etype];
@@ -86,13 +77,6 @@ void SpMMCsrHetero(const std::string& op, const std::string& reduce,
   } else if (reduce == "max" || reduce == "min") {
     SWITCH_BITS(bits, DType, {
       SWITCH_OP(op, Op, {
-         // TODO(Israt): Ideally the for loop should go over num_ntypes
-        for (dgl_type_t etype = 0; etype < ufeat_node_tids.size(); ++etype) {
-          IdType* argX = Op::use_lhs ? static_cast<IdType*>(out_aux[0]->data) : nullptr;
-          IdType* argW = Op::use_rhs ? static_cast<IdType*>(out_aux[1]->data) : nullptr;
-          if (Op::use_lhs) std::fill(argX, argX + vec_csr[etype].num_rows * dim, 0);
-          if (Op::use_rhs) std::fill(argW, argW + vec_csr[etype].num_rows * dim, 0);
-        }
         /* Call  SpMM for each relation type */
         for (dgl_type_t etype = 0; etype < ufeat_node_tids.size(); ++etype) {
           const dgl_type_t src_id = ufeat_node_tids[etype];