fix codex warning

mindspore/ccsrc/backend/optimizer/graph_kernel/add_atomic_clean.cc

@@ -52,7 +52,7 @@ std::set<int64_t> GetUniqReduceAxes(const AnfNodePtr &node, bool is_ascend = fal
   auto axis_vec = GetReduceAxis(node);
   if (axis_vec.empty()) {
     for (size_t i = 0; i < src_shape_vec.size(); ++i) {
-      axis_vec.emplace_back(SizeToLong(i));
+      (void)axis_vec.emplace_back(SizeToLong(i));
     }
   } else {
     (void)std::transform(axis_vec.begin(), axis_vec.end(), axis_vec.begin(), [&src_shape_vec](int64_t axis) -> int64_t {

mindspore/ccsrc/backend/optimizer/graph_kernel/parallel_fusion.cc

@@ -557,7 +557,7 @@ std::tuple<std::vector<bool>, std::vector<ParallelInfo>> ParallelOpFusion::Searc
   std::vector<size_t> indices;
   for (size_t i = 0; i < cs.size(); ++i) {
     if (cs[i]) {
-      origin_indices.insert({cs[i], i});
+      origin_indices.emplace(cs[i], i);
       indices.push_back(i);
     }
   }

mindspore/ccsrc/utils/context/graph_kernel_flags.cc

@@ -32,11 +32,11 @@ std::vector<std::string> GetTokens(const std::string &str, const std::string &de
   std::vector<std::string> tokens;
   std::vector<char> c_str(str.begin(), str.end());
   c_str.push_back('\0');
-  char *saveptr;
+  char *saveptr = nullptr;
   char *pch = strtok_r(&c_str[0], delim.c_str(), &saveptr);
-  while (pch != NULL) {
+  while (pch != nullptr) {
     tokens.emplace_back(pch);
-    pch = strtok_r(NULL, delim.c_str(), &saveptr);
+    pch = strtok_r(nullptr, delim.c_str(), &saveptr);
   }
   return tokens;
 }
@@ -44,19 +44,19 @@ std::vector<std::string> GetTokens(const std::string &str, const std::string &de
 // Parse flag string to key-value pair.
 // Flag format: "--key=value", bool flag's value can be implicit, the "--key" means "--key=true"
 std::pair<std::string, std::string> ParseFlag(const std::string &flag) {
-  auto i = flag.find("--");
   // check the string starts with "--".
-  constexpr size_t expected_size = 2;
-  if (i != 0 || flag.size() == expected_size) {
+  auto i = flag.find("--");
+  constexpr size_t leading_size = 2;
+  if (flag.size() <= leading_size || i != 0) {
     return std::pair<std::string, std::string>();
   }
-  i += expected_size;
+  i += leading_size;
 
   auto j = flag.find('=', i + 1);  // the key should not be empty, "--=" is invalid
-  if (j == std::string::npos) {
+  if (j >= flag.size()) {
     // no value, treated as bool flag.
     return std::make_pair(flag.substr(i), "");
-  } else if (j + 1 != flag.size() && flag.find('=', j + 1) == std::string::npos) {
+  } else if (j + 1 < flag.size() && flag.find('=', j + 1) == std::string::npos) {
     // normal "--key=value" format
     return std::make_pair(flag.substr(i, j - i), flag.substr(j + 1));
   }

mindspore/ccsrc/utils/context/graph_kernel_flags.h

@@ -65,19 +65,19 @@ class GraphKernelFlags {
    *
    * Experimental feature, enabled by default when opt_level=3
    */
-  bool enable_stitch_fusion;
+  bool enable_stitch_fusion{false};
 
   /**
    * Enable recompute fusion in graph kernel fusion strategy, enabled when op_level>=2.
    */
-  bool enable_recompute_fusion;
+  bool enable_recompute_fusion{true};
 
   /**
    * Enable parallel fusion in graph kernel fusion strategy.
    *
    * Experimental feature, enabled by default when opt_level=3
    */
-  bool enable_parallel_fusion;
+  bool enable_parallel_fusion{false};
 
   /**
    * Optimization level, value from 0 to 3.
@@ -88,7 +88,7 @@ class GraphKernelFlags {
    * The default value is OptLevel_2 when the context "enable_graph_kernel" is set,
    * but if it's also changed in "graph_kernel_flags", then the "graph_kernel_flags" will prevail.
    */
-  unsigned int opt_level;  // defaults 0 or 2
+  unsigned int opt_level{0};  // defaults 0 or 2
 
   /**
    * auto_tune, unsupported now.