make target check more robust

Author: cblmemo

src/meta_schedule/schedule_rule/multi_level_tiling.cc

@@ -87,15 +87,18 @@ void MultiLevelTilingNode::InitializeWithTuneContext(const TuneContext& context)
       TVM_PY_LOG(INFO, context->logger) << "'thread_warp_size' is not defined in the target";
     }
   }
-  Optional<String> arch_attr = context->target.value()->GetAttr<String>("arch");
-  if (arch_attr.defined()) {
-    String arch = arch_attr.value();
-    // format: sm_xx
-    // @see src/target/tag.cc
-    if (arch.size() == 5 && (strncmp(arch.c_str(), "sm_", 3) == 0)) {
-      // only sm_80 or higher supports async memcopy
-      if (arch.at(3) >= '8') {
-        this->stages.insert(this->stages.end(), {4, 5});
+  if (Optional<String> opt_sm = context->target.value()->GetAttr<String>("arch")) {
+    std::string sm = opt_sm.value();
+    if (support::StartsWith(sm, "sm_")) {
+      sm = sm.substr(3);
+      try {
+        // only sm_80 or higher supports async memcopy
+        if (std::stoi(sm) >= 80) {
+          this->stages.insert(this->stages.end(), {4, 5});
+        }
+      } catch (const std::invalid_argument& e) {
+        LOG(WARNING) << "ValueError: Unable to parse `target.arch`: " << sm
+                     << ". Details: " << e.what();
       }
     }
   }