[Bugfix] Fix #8536 Get Target When Heterogeneous Execution

src/relay/backend/te_compiler.cc

@@ -372,42 +372,8 @@ class LowerTensorExpr : public ExprMutator {
            "in the memory planner.";
 
     auto& device_context = this->device_context_map_[expr];
-    auto call_dev_type = device_context.device_type;
-
+    target = GetTargetFromInteger(device_context.device_type, targets_);
     // Non-External Relay Function
-    if (targets_.size() == 1) {
-      // The homogeneous execution case, we should only have one target
-      // so we just grab it.
-      const auto& it = targets_.begin();
-      target = (*it).second;
-    } else {
-      // The heterogeneous execution case we have multiple targets
-      // in this case.
-      //
-      // We need to identify the target and translate.
-      std::string call_dev_name;
-      if (call_dev_type == 0) {
-        call_dev_name = "llvm";
-        call_dev_type = kDLCPU;
-      } else {
-        call_dev_name = ::tvm::runtime::DeviceName(call_dev_type);
-      }
-
-      if (targets_.count(call_dev_type) == 0) {
-        std::stringstream msg;
-        msg << "No target is specified for provided device name: `" << call_dev_name << "`\n\n";
-        msg << call_dev_name << " mapped to device type (" << call_dev_type
-            << ") which was not found in the target map.\n";
-        msg << "Availible targets: \n";
-        for (auto target : targets_) {
-          msg << "  " << target.first << "-> " << target.second << "\n";
-        }
-        LOG(FATAL) << msg.str();
-      }
-
-      target = targets_[call_dev_type];
-    }
-
     CCacheKey key = CCacheKey(func, target);
     CachedFunc lowered_func = compiler_->Lower(key, module_name_);
 
@@ -465,19 +431,29 @@ class LowerTensorExpr : public ExprMutator {
  */
 Target GetTargetFromInteger(DLDeviceType dev_type, TargetMap targets) {
   if (targets.size() == 1) {
-    // homogeneous execution.
+    // The homogeneous execution case, return the only target.
     const auto& it = targets.begin();
     return (*it).second;
   } else {
-    // heterogeneous execution.
-    std::string call_dev_name;
-    if (dev_type == 0) {
-      call_dev_name = "llvm";
-    } else {
-      call_dev_name = runtime::DeviceName(dev_type);
+    // The heterogeneous execution case, return the target associated with the
+    // given device type.
+    // If "dev_type" equals to 0, the device name only can be got from
+    // "targets", and it may not be "llvm", so here just set it to "unknown".
+    std::string dev_name = "unknown";
+    if (dev_type != 0) {
+      dev_name = runtime::DeviceName(dev_type);
     }
+
     if (targets.count(dev_type) == 0) {
-      LOG(FATAL) << "No target is provided for device " << call_dev_name;
+      std::stringstream msg;
+      msg << "No target is specified for provided device name: `" << dev_name << "`\n\n"
+          << dev_name << " mapped to device type (" << dev_type
+          << ") which was not found in the target map.\n"
+          << "Availible targets: \n";
+      for (auto target : targets) {
+        msg << "  " << target.first << "-> " << target.second << "\n";
+      }
+      LOG(FATAL) << msg.str();
     }
     return targets[dev_type];
   }