Persist provider options across ClearProviders, AppendProvider where possible

src/config.cpp

@@ -54,7 +54,9 @@ struct ProviderOptionsObject_Element : JSON::Element {
 };
 
 struct ProviderOptionsArray_Element : JSON::Element {
-  explicit ProviderOptionsArray_Element(std::vector<Config::ProviderOptions>& v) : v_{v} {}
+  explicit ProviderOptionsArray_Element(std::vector<Config::ProviderOptions>& v,
+                                        std::vector<Config::ProviderOptions>* v_backup = nullptr)
+      : v_{v}, v_backup_{v_backup} {}
 
   JSON::Element& OnObject(std::string_view name) override { return object_; }
 
@@ -69,10 +71,18 @@ struct ProviderOptionsArray_Element : JSON::Element {
         v.name = "DML";
       }
     }
+
+    // Copy the provider options to the backup vector.
+    // The backup is used to restore the original provider options when
+    // AppendProvider is called with the same provider name.
+    if (v_backup_) {
+      *v_backup_ = v_;
+    }
   }
 
  private:
   std::vector<Config::ProviderOptions>& v_;
+  std::vector<Config::ProviderOptions>* v_backup_;
   ProviderOptionsObject_Element object_{v_};
 };
 
@@ -143,7 +153,7 @@ struct SessionOptions_Element : JSON::Element {
 
  private:
   Config::SessionOptions& v_;
-  ProviderOptionsArray_Element provider_options_{v_.provider_options};
+  ProviderOptionsArray_Element provider_options_{v_.provider_options, &v_.provider_options_backup};
   NamedStrings_Element config_entries_{v_.config_entries};
 };
 
@@ -715,6 +725,20 @@ void ClearProviders(Config& config) {
 }
 
 void SetProviderOption(Config& config, std::string_view provider_name, std::string_view option_name, std::string_view option_value) {
+  for (auto& provider_options : config.model.decoder.session_options.provider_options_backup) {
+    // If config.model.decoder.session_options.provider_options already has the provider name, add the requested option to it.
+    // Otherwise, if the provider name is found in the backup, query the provider options from the backup and add them to the current provider options.
+    // Otherwise, create a new provider options object and add it to the current provider options.
+    // This ensures that any __required__ options specified in the genai_config.json are not lost when ClearProviders -> AppendProvider is called.
+    // This is important for providers like Cuda, which require certain options to be set for some models.
+    if (provider_options.name == provider_name &&
+        std::none_of(config.model.decoder.session_options.provider_options.begin(),
+                     config.model.decoder.session_options.provider_options.end(),
+                     [&provider_name](const Config::ProviderOptions& po) { return po.name == provider_name; })) {
+      config.model.decoder.session_options.provider_options.emplace_back(provider_options);
+      return;
+    }
+  }
   std::ostringstream json;
   json << R"({")" << provider_name << R"(":{)";
   if (!option_name.empty()) {

src/config.h

@@ -74,6 +74,7 @@ struct Config {
     std::vector<NamedString> config_entries;  // Entries go into OrtSessionOptions::AddConfigEntry
 
     std::vector<ProviderOptions> provider_options;
+    std::vector<ProviderOptions> provider_options_backup;
     std::optional<GraphOptimizationLevel> graph_optimization_level;
   };