Add a default image prefiller implementation (#13310)

Summary:

As titled. I need to create an interface `IModule` for `Module` class to override, to make it test-able.

Reviewed By: jackzhxng

Differential Revision: D80063769

Author: larryliu0820

extension/llm/runner/multimodal_decoder_runner.h

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <executorch/extension/llm/runner/constants.h>
+#include <executorch/extension/llm/runner/text_decoder_runner.h>
+
+namespace executorch::extension::llm {
+
+class ET_EXPERIMENTAL MultimodalDecoderRunner
+    : public executorch::extension::llm::TextDecoderRunner {
+ public:
+  explicit MultimodalDecoderRunner(Module* module, IOManager* io_manager)
+      : TextDecoderRunner(module, io_manager) {}
+
+  /**
+   * Step the LLM Decoder with the given tokens and start position.
+   * @param tokens The tokens to the LLM.
+   * @param start_pos The start position of the tokens.
+   * @return The logits tensor.
+   */
+  inline executorch::runtime::Result<executorch::aten::Tensor> step(
+      executorch::extension::TensorPtr& tokens,
+      int64_t start_pos) override {
+    // run token embedding
+    auto token_embedding_outputs =
+        ET_UNWRAP(module_->execute(kTokenEmbeddingMethod, tokens));
+
+    // Return the logits tensor
+    return decode(token_embedding_outputs[0], start_pos);
+  }
+
+  /**
+   * Decode the embeddings to logits.
+   * @param embeddings The embeddings tensor.
+   * @param start_pos The start position of the embeddings.
+   * @return The logits tensor.
+   */
+  inline executorch::runtime::Result<executorch::aten::Tensor> decode(
+      const runtime::EValue& embeddings,
+      int64_t start_pos) {
+    auto start_pos_tensor = ::executorch::extension::from_blob(
+        &start_pos, {1}, executorch::aten::ScalarType::Long);
+    // run text model
+    auto outputs_res = ET_UNWRAP(
+        module_->execute(kTextModelMethod, {start_pos_tensor, embeddings}));
+
+    ET_CHECK_MSG(
+        outputs_res.size() == 1,
+        "More then one output returned from executing LLM.");
+    ET_CHECK_MSG(
+        outputs_res[0].isTensor(),
+        "Non Tensor Output returned from executing LLM");
+
+    // Return the logits tensor
+    return outputs_res[0].toTensor();
+  }
+
+  /**
+   * Load the Module for text decode purpose.
+   * @return The error code.
+   */
+  inline executorch::runtime::Error load() override {
+    if (is_method_loaded()) {
+      return executorch::runtime::Error::Ok;
+    }
+    ET_CHECK_OK_OR_RETURN_ERROR(module_->load_method(kTokenEmbeddingMethod));
+    ET_CHECK_OK_OR_RETURN_ERROR(module_->load_method(kTextModelMethod));
+    return executorch::runtime::Error::Ok;
+  }
+
+  /**
+   * Check if the required methods in the Module is loaded.
+   * @return True if the Module is loaded, false otherwise.
+   */
+  inline bool is_method_loaded() override {
+    executorch::runtime::Result<std::unordered_set<std::string>> methods_res =
+        module_->method_names();
+    if (methods_res.error() != executorch::runtime::Error::Ok) {
+      ET_CHECK_MSG(false, "Failed to get method names");
+    }
+    std::unordered_set<std::string> methods = methods_res.get();
+    bool methods_exist = methods.find(kTokenEmbeddingMethod) != methods.end() &&
+        methods.find(kTextModelMethod) != methods.end();
+    if (!methods_exist) {
+      for (const auto& method : methods) {
+        ET_LOG(Error, "Method: %s", method.c_str());
+      }
+      ET_CHECK_MSG(
+          methods_exist,
+          "Missing required methods (%s, %s) in the model",
+          kTokenEmbeddingMethod,
+          kTextModelMethod);
+    }
+    bool methods_loaded = module_->is_method_loaded(kTokenEmbeddingMethod) &&
+        module_->is_method_loaded(kTextModelMethod);
+    return methods_loaded;
+  }
+};
+
+} // namespace executorch::extension::llm

extension/llm/runner/multimodal_input.h

@@ -0,0 +1,167 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// A generic multimodal input class that can hold either image or text data.
+
+#pragma once
+
+#include <executorch/extension/llm/runner/image.h>
+#include <executorch/runtime/platform/compiler.h>
+#include <string>
+#include <variant>
+
+namespace executorch {
+namespace extension {
+namespace llm {
+
+/**
+ * A generic class to hold either image or text data for multimodal inputs.
+ * This allows the generate() API to take a std::vector of these objects
+ * instead of separate image and text parameters.
+ */
+class ET_EXPERIMENTAL MultimodalInput {
+ public:
+  enum class Type { TEXT, IMAGE };
+
+  // Constructors
+  explicit MultimodalInput(const std::string& text) : data_(text) {}
+  explicit MultimodalInput(std::string&& text) : data_(std::move(text)) {}
+  explicit MultimodalInput(const Image& image) : data_(image) {}
+  explicit MultimodalInput(Image&& image) : data_(std::move(image)) {}
+
+  // Copy constructor and assignment
+  MultimodalInput(const MultimodalInput& other) = default;
+  MultimodalInput& operator=(const MultimodalInput& other) = default;
+
+  // Move constructor and assignment
+  MultimodalInput(MultimodalInput&& other) noexcept = default;
+  MultimodalInput& operator=(MultimodalInput&& other) noexcept = default;
+
+  // Destructor
+  ~MultimodalInput() = default;
+
+  /**
+   * Check if this input contains text data.
+   * @return true if this input contains text, false otherwise.
+   */
+  bool is_text() const {
+    return std::holds_alternative<std::string>(data_);
+  }
+
+  /**
+   * Check if this input contains image data.
+   * @return true if this input contains an image, false otherwise.
+   */
+  bool is_image() const {
+    return std::holds_alternative<Image>(data_);
+  }
+
+  /**
+   * Get the type of data stored in this input.
+   * @return Type::TEXT if text data, Type::IMAGE if image data.
+   */
+  Type get_type() const {
+    return is_text() ? Type::TEXT : Type::IMAGE;
+  }
+
+  /**
+   * Get the text data from this input.
+   * @return Reference to the stored text string.
+   * @throws std::bad_variant_access if this input doesn't contain text.
+   */
+  const std::string& get_text() const {
+    return std::get<std::string>(data_);
+  }
+
+  /**
+   * Get the text data from this input (mutable version).
+   * @return Mutable reference to the stored text string.
+   * @throws std::bad_variant_access if this input doesn't contain text.
+   */
+  std::string& get_text() {
+    return std::get<std::string>(data_);
+  }
+
+  /**
+   * Get the image data from this input.
+   * @return Reference to the stored Image object.
+   * @throws std::bad_variant_access if this input doesn't contain an image.
+   */
+  const Image& get_image() const {
+    return std::get<Image>(data_);
+  }
+
+  /**
+   * Get the image data from this input (mutable version).
+   * @return Mutable reference to the stored Image object.
+   * @throws std::bad_variant_access if this input doesn't contain an image.
+   */
+  Image& get_image() {
+    return std::get<Image>(data_);
+  }
+
+  /**
+   * Try to get the text data from this input safely.
+   * @return Pointer to the text string if this input contains text, nullptr
+   * otherwise.
+   */
+  const std::string* try_get_text() const {
+    return std::get_if<std::string>(&data_);
+  }
+
+  /**
+   * Try to get the text data from this input safely (mutable version).
+   * @return Pointer to the text string if this input contains text, nullptr
+   * otherwise.
+   */
+  std::string* try_get_text() {
+    return std::get_if<std::string>(&data_);
+  }
+
+  /**
+   * Try to get the image data from this input safely.
+   * @return Pointer to the Image object if this input contains an image,
+   * nullptr otherwise.
+   */
+  const Image* try_get_image() const {
+    return std::get_if<Image>(&data_);
+  }
+
+  /**
+   * Try to get the image data from this input safely (mutable version).
+   * @return Pointer to the Image object if this input contains an image,
+   * nullptr otherwise.
+   */
+  Image* try_get_image() {
+    return std::get_if<Image>(&data_);
+  }
+
+ private:
+  std::variant<std::string, Image> data_;
+};
+
+// Convenience factory functions
+inline MultimodalInput make_text_input(const std::string& text) {
+  return MultimodalInput(text);
+}
+
+inline MultimodalInput make_text_input(std::string&& text) {
+  return MultimodalInput(std::move(text));
+}
+
+inline MultimodalInput make_image_input(const Image& image) {
+  return MultimodalInput(image);
+}
+
+inline MultimodalInput make_image_input(Image&& image) {
+  return MultimodalInput(std::move(image));
+}
+
+} // namespace llm
+} // namespace extension
+} // namespace executorch