From eada00c254440064976ff760c322d464068cf7c2 Mon Sep 17 00:00:00 2001
From: superjomn <yanchunwei@outlook.com>
Date: Wed, 17 Apr 2019 19:04:54 +0800
Subject: [PATCH] init optimizer

---
 paddle/fluid/lite/core/CMakeLists.txt         |  7 +++
 paddle/fluid/lite/core/kernel.h               | 21 ++++++--
 paddle/fluid/lite/core/mir/CMakeLists.txt     |  5 +-
 .../lite/core/mir/generate_program_pass.cc    | 14 +++++
 .../lite/core/mir/generate_program_pass.h     |  3 +-
 .../fluid/lite/core/mir/io_complement_pass.cc | 15 ++++++
 .../fluid/lite/core/mir/io_complement_pass.h  |  3 +-
 paddle/fluid/lite/core/mir/pass_manager.cc    |  1 -
 paddle/fluid/lite/core/mir/pass_manager.h     | 17 ++++--
 paddle/fluid/lite/core/mir/ssa_graph_test.cc  | 54 +------------------
 .../lite/core/mir/static_kernel_pick_pass.cc  | 46 ++++++++++++++++
 .../lite/core/mir/static_kernel_pick_pass.h   | 54 ++++++++++++++++++-
 paddle/fluid/lite/core/op_registry.h          |  6 ++-
 paddle/fluid/lite/core/optimizer.h            | 13 ++---
 paddle/fluid/lite/core/types.h                | 32 +++++++++++
 15 files changed, 217 insertions(+), 74 deletions(-)

diff --git a/paddle/fluid/lite/core/CMakeLists.txt b/paddle/fluid/lite/core/CMakeLists.txt
index 6fd696d5d8c..c7e86290853 100644
--- a/paddle/fluid/lite/core/CMakeLists.txt
+++ b/paddle/fluid/lite/core/CMakeLists.txt
@@ -9,8 +9,14 @@ cc_library(op_executor_lite SRCS op_executor.cc DEPS scope_lite tensor_lite op_l
   #TODO(Superjomn) remove these dependencies from original framework
   proto_desc)
 cc_library(kernel_executor_lite SRCS kernel_executor.cc DEPS mir_ssa_graph kernel_lite)
+cc_library(types_lite SRCS types.cc)
 cc_library(type_system SRCS type_system.cc DEPS tensor_lite)
 cc_library(optimizer_lite SRCS optimizer.cc DEPS mir_pass_manager)
+cc_library(program_fake_utils SRCS program_fake_utils.cc DEPS mir_ssa_graph
+  scope_lite op_registry_lite proto_desc op_lite
+  ops_lite
+  host_kernels
+  )
 
 cc_test(test_scope_lite SRCS scope_test.cc DEPS scope_lite)
 cc_test(test_kernel_lite SRCS kernel_test.cc DEPS target_wrapper_x86)
@@ -18,5 +24,6 @@ cc_test(test_op_lite SRCS op_lite_test.cc DEPS op_lite)
 cc_test(test_tensor_lite SRCS tensor_test.cc)
 cc_test(test_op_executor_lite SRCS op_executor_test.cc DEPS op_executor_lite ops_lite host_kernels)
 cc_test(test_type_system SRCS type_system_test.cc DEPS type_system)
+cc_test(test_optimizer_lite SRCS optimizer_test.cc DEPS mir_pass_manager program_fake_utils mir_passes)
 
 add_subdirectory(mir)
diff --git a/paddle/fluid/lite/core/kernel.h b/paddle/fluid/lite/core/kernel.h
index ee6890aea96..f83ae0a5222 100644
--- a/paddle/fluid/lite/core/kernel.h
+++ b/paddle/fluid/lite/core/kernel.h
@@ -15,7 +15,9 @@
 #pragma once
 
 #include <map>
+#include <set>
 #include <string>
+#include <vector>
 #include "paddle/fluid/framework/op_desc.h"
 #include "paddle/fluid/lite/core/context.h"
 #include "paddle/fluid/lite/core/target_wrapper.h"
@@ -48,17 +50,24 @@ class KernelBase {
     return param_.get<Param>();
   }
 
+  void set_op_type(const std::string& type) { op_type_ = type; }
+  const std::string& op_type() const { return op_type_; }
+
   void Torch() {}
 
   virtual TargetType target() const = 0;
   virtual PrecisionType precision() const = 0;
   virtual DataLayoutType layout() const = 0;
 
+  virtual std::string name() const = 0;
+
   virtual ~KernelBase() = default;
 
  protected:
   core::any_context_t context_;
   mutable operators::param_t param_;
+  // The corresponding op type.
+  std::string op_type_;
 };
 
 /*
@@ -73,8 +82,9 @@ struct ParamType {
   Place tensor_place{};
   const Type* type_;
 
-  ParamType() = default;
-  ParamType(size_t element_type_hash) : element_type_hash(element_type_hash) {}
+  explicit ParamType() = default;
+  explicit ParamType(size_t element_type_hash)
+      : element_type_hash(element_type_hash) {}
   ParamType(size_t element_type_hash, const Place& place)
       : element_type_hash(element_type_hash), tensor_place(place) {}
   ParamType(const Type* type) : type_(type) {}
@@ -135,7 +145,8 @@ class ParamTypeRegistry {
    *                                               PRECISION(kFloat)});
    */
   struct NewInstance {
-    NewInstance(const std::string& kernel_type) : kernel_type_(kernel_type) {}
+    explicit NewInstance(const std::string& kernel_type)
+        : kernel_type_(kernel_type) {}
 
     NewInstance& BindInput(int offset, const ParamType& ptype) {
       ParamTypeRegistry::Global().Register<IO::kInput>(
@@ -205,6 +216,10 @@ class OpKernel : public KernelBase {
   TargetType target() const override { return Target; }
   PrecisionType precision() const override { return Precision; }
   DataLayoutType layout() const override { return DataLayout; }
+  std::string name() const override {
+    return op_type() + ":" + TargetToStr(Target) + "/" +
+           PrecisionToStr(Precision) + "/" + DataLayoutToStr(DataLayout);
+  }
 
   void Touch() {}
 
diff --git a/paddle/fluid/lite/core/mir/CMakeLists.txt b/paddle/fluid/lite/core/mir/CMakeLists.txt
index 5e789829abb..757e5e141fd 100644
--- a/paddle/fluid/lite/core/mir/CMakeLists.txt
+++ b/paddle/fluid/lite/core/mir/CMakeLists.txt
@@ -9,13 +9,14 @@ cc_library(mir_passes
         graph_visualize_pass.cc
         generate_program_pass.cc
         demo_pass.cc
-        DEPS mir_pass)
+        DEPS mir_pass types_lite)
 
 cc_test(test_mir_pass_manager SRCS pass_manager_test.cc DEPS mir_pass_manager mir_passes)
 cc_test(test_ssa_graph SRCS ssa_graph_test.cc DEPS
         mir_ssa_graph scope_lite op_lite
-        proto_desc ops_lite
+        ops_lite
         host_kernels
         mir_passes
         mir_pass_manager
+        program_fake_utils
         )
diff --git a/paddle/fluid/lite/core/mir/generate_program_pass.cc b/paddle/fluid/lite/core/mir/generate_program_pass.cc
index ce71e4de2b8..0be516489db 100644
--- a/paddle/fluid/lite/core/mir/generate_program_pass.cc
+++ b/paddle/fluid/lite/core/mir/generate_program_pass.cc
@@ -11,3 +11,17 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+
+#include "paddle/fluid/lite/core/mir/generate_program_pass.h"
+#include "paddle/fluid/lite/core/mir/pass_registry.h"
+
+namespace paddle {
+namespace lite {
+namespace mir {
+void GenerateProgramPass::Apply(std::unique_ptr<mir::SSAGraph> &graph) {}
+}  // namespace mir
+}  // namespace lite
+}  // namespace paddle
+
+REGISTER_MIR_PASS(generate_program_pass,
+                  paddle::lite::mir::GenerateProgramPass);
diff --git a/paddle/fluid/lite/core/mir/generate_program_pass.h b/paddle/fluid/lite/core/mir/generate_program_pass.h
index bee6a3c8f66..bc78370b08d 100644
--- a/paddle/fluid/lite/core/mir/generate_program_pass.h
+++ b/paddle/fluid/lite/core/mir/generate_program_pass.h
@@ -24,8 +24,9 @@ namespace mir {
  * GenerateProgramPass will build the execution program for executor from a mir
  * graph.
  */
-class GenerateProgramPass : public Pass {
+class GenerateProgramPass : public ProgramPass {
  public:
+  void Apply(std::unique_ptr<mir::SSAGraph> &graph) override;
 };
 
 }  // namespace mir
diff --git a/paddle/fluid/lite/core/mir/io_complement_pass.cc b/paddle/fluid/lite/core/mir/io_complement_pass.cc
index ce71e4de2b8..8511a3921f5 100644
--- a/paddle/fluid/lite/core/mir/io_complement_pass.cc
+++ b/paddle/fluid/lite/core/mir/io_complement_pass.cc
@@ -11,3 +11,18 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+
+#include "paddle/fluid/lite/core/mir/io_complement_pass.h"
+#include "paddle/fluid/lite/core/mir/pass_registry.h"
+
+namespace paddle {
+namespace lite {
+namespace mir {
+
+void IoComplementPass::Apply(std::unique_ptr<mir::SSAGraph> &graph) {}
+
+}  // namespace mir
+}  // namespace lite
+}  // namespace paddle
+
+REGISTER_MIR_PASS(io_complement_pass, paddle::lite::mir::IoComplementPass);
diff --git a/paddle/fluid/lite/core/mir/io_complement_pass.h b/paddle/fluid/lite/core/mir/io_complement_pass.h
index ff071ce037e..b44fde7b450 100644
--- a/paddle/fluid/lite/core/mir/io_complement_pass.h
+++ b/paddle/fluid/lite/core/mir/io_complement_pass.h
@@ -24,8 +24,9 @@ namespace mir {
  * IoComplementPass complement the necessary instruction to make data
  * transferring or transformation between different places.
  */
-class IoComplementPass : public Pass {
+class IoComplementPass : public ProgramPass {
  public:
+  void Apply(std::unique_ptr<mir::SSAGraph> &graph) override;
 };
 
 }  // namespace mir
diff --git a/paddle/fluid/lite/core/mir/pass_manager.cc b/paddle/fluid/lite/core/mir/pass_manager.cc
index 6e1c0cd9f5f..508c2fd5522 100644
--- a/paddle/fluid/lite/core/mir/pass_manager.cc
+++ b/paddle/fluid/lite/core/mir/pass_manager.cc
@@ -13,7 +13,6 @@
 // limitations under the License.
 
 #include "paddle/fluid/lite/core/mir/pass_manager.h"
-#include "paddle/fluid/lite/core/mir/pass_registry.h"
 
 namespace paddle {
 namespace lite {
diff --git a/paddle/fluid/lite/core/mir/pass_manager.h b/paddle/fluid/lite/core/mir/pass_manager.h
index e2ff6549bd5..ba3fad4d9f2 100644
--- a/paddle/fluid/lite/core/mir/pass_manager.h
+++ b/paddle/fluid/lite/core/mir/pass_manager.h
@@ -32,16 +32,17 @@ class PassManager {
 
   PassManager();
 
-  void Run() {
+  void Run(std::unique_ptr<SSAGraph>& graph) {
     for (auto& pass : passes_) {
       LOG(INFO) << "Running MIR pass " << pass->name();
-      pass->Apply(graph_);
+      pass->Apply(graph);
     }
   }
 
   bool AddNewPass(const std::string& name, Pass* pass) {
     passes_.emplace_back(pass);
     pass_map_.emplace(name, passes_.back().get());
+    passes_.back()->set_name(name);
     return true;
   }
 
@@ -65,12 +66,18 @@ class PassManager {
 
   Pass* LookUp(const std::string& key) {
     auto it = pass_map_.find(key);
-    CHECK(it != pass_map_.end());
-    return it->second;
+    if (it != pass_map_.end()) return it->second;
+    return nullptr;
+  }
+
+  template <typename PassTy>
+  PassTy* LookUp(const std::string& key) {
+    auto it = pass_map_.find(key);
+    if (it != pass_map_.end()) return dynamic_cast<PassTy*>(it->second);
+    return nullptr;
   }
 
  private:
-  std::unique_ptr<mir::SSAGraph> graph_;
   std::list<std::unique_ptr<mir::Pass>> passes_;
   std::map<std::string, mir::Pass*> pass_map_;
 };
diff --git a/paddle/fluid/lite/core/mir/ssa_graph_test.cc b/paddle/fluid/lite/core/mir/ssa_graph_test.cc
index 0db9164e7e2..76f595a913a 100644
--- a/paddle/fluid/lite/core/mir/ssa_graph_test.cc
+++ b/paddle/fluid/lite/core/mir/ssa_graph_test.cc
@@ -16,7 +16,9 @@
 #include <gtest/gtest.h>
 #include "paddle/fluid/framework/program_desc.h"
 #include "paddle/fluid/lite/core/mir/graph_visualize_pass.h"
+#include "paddle/fluid/lite/core/mir/passes.h"
 #include "paddle/fluid/lite/core/op_registry.h"
+#include "paddle/fluid/lite/core/program_fake_utils.h"
 
 namespace paddle {
 namespace lite {
@@ -32,58 +34,6 @@ void BuildFc(framework::ProgramDesc* desc, const std::string& x,
   fc->SetOutput("Out", {out});
 }
 
-Program FakeProgram() {
-  Program program;
-  program.scope = new lite::Scope;
-
-  auto add_fc = [&](int id, std::string x) {
-    // create variables
-    std::string w1 = "w" + std::to_string(id);
-    std::string b1 = "b" + std::to_string(id);
-    std::string out1 = "out" + std::to_string(id);
-    auto w1v = program.scope->Var(w1)->GetMutable<Tensor>();
-    auto b1v = program.scope->Var(b1)->GetMutable<Tensor>();
-    auto out1v = program.scope->Var(out1)->GetMutable<Tensor>();
-
-    framework::OpDesc desc;
-    desc.SetInput("Input", {x});
-    desc.SetInput("W", {w1});
-    desc.SetInput("Bias", {b1});
-    desc.SetOutput("Out", {out1});
-    desc.SetType("fc");
-    desc.SetAttr("in_num_col_dims", 1);
-    desc.Flush();
-
-    // add to input
-    program.tmp_vars.push_back(w1);
-    program.tmp_vars.push_back(b1);
-
-    auto fc_op = LiteOpRegistry::Global().Create("fc");
-    fc_op->PickKernel({Place{TARGET(kHost), PRECISION(kFloat)}});
-    fc_op->Attach(desc, program.scope);
-    program.ops.emplace_back(std::move(fc_op));
-
-    w1v->Resize({100, 100});
-    b1v->Resize({100, 1});
-    out1v->Resize({100, 100});
-
-    return out1;
-  };
-
-  // x1, w1, b1 -fc-> out1
-  // out1, w2, b2 -fc-> out2
-
-  std::string x = "x";
-  program.tmp_vars.push_back(x);
-  auto* xv = program.scope->Var(x)->GetMutable<Tensor>();
-  xv->Resize({100, 100});
-
-  for (int i = 0; i < 3; i++) {
-    x = add_fc(i, x);
-  }
-  return program;
-}
-
 TEST(SSAGraph, test) {
   auto program = FakeProgram();
   SSAGraph graph;
diff --git a/paddle/fluid/lite/core/mir/static_kernel_pick_pass.cc b/paddle/fluid/lite/core/mir/static_kernel_pick_pass.cc
index ce71e4de2b8..8a324a6cca2 100644
--- a/paddle/fluid/lite/core/mir/static_kernel_pick_pass.cc
+++ b/paddle/fluid/lite/core/mir/static_kernel_pick_pass.cc
@@ -11,3 +11,49 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
+
+#include "paddle/fluid/lite/core/mir/static_kernel_pick_pass.h"
+#include <algorithm>
+#include <utility>
+#include <vector>
+#include "paddle/fluid/lite/core/mir/pass_registry.h"
+
+namespace paddle {
+namespace lite {
+namespace mir {
+
+bool KernelScoreCmp(const std::pair<size_t, std::unique_ptr<KernelBase>>& a,
+                    const std::pair<size_t, std::unique_ptr<KernelBase>>& b) {
+  return a.first > b.first;
+}
+
+void StaticKernelPickPass::Apply(std::unique_ptr<mir::SSAGraph>& graph) {
+  CHECK(kernel_pick_factors_.AnyFactorConsidered())
+      << "kernel_pick_factors should be specified first";
+  CHECK(graph) << "graph not valid";
+  // sort kernels by the factors.
+  for (auto& node : graph->mutable_nodes()) {
+    if (!node.IsInstruct()) continue;
+    auto& instruct = node.AsInstruct();
+    std::vector<std::pair<size_t, std::unique_ptr<KernelBase>>> scored;
+    for (auto&& kernel : instruct.valid_kernels) {
+      scored.emplace_back(KernelGrade(*kernel), std::move(kernel));
+    }
+
+    std::sort(scored.begin(), scored.end(), KernelScoreCmp);
+
+    // Move kernel back
+    // Just keep a single best kernel.
+    // TODO(Superjomn) reconsider this.
+    instruct.valid_kernels.clear();
+    instruct.valid_kernels.emplace_back(std::move(scored.front().second));
+    LOG(INFO) << "pick " << instruct.valid_kernels.front()->name();
+  }
+}
+
+}  // namespace mir
+}  // namespace lite
+}  // namespace paddle
+
+REGISTER_MIR_PASS(static_kernel_pick_pass,
+                  paddle::lite::mir::StaticKernelPickPass);
diff --git a/paddle/fluid/lite/core/mir/static_kernel_pick_pass.h b/paddle/fluid/lite/core/mir/static_kernel_pick_pass.h
index becdd50dd91..9cf3ee2d439 100644
--- a/paddle/fluid/lite/core/mir/static_kernel_pick_pass.h
+++ b/paddle/fluid/lite/core/mir/static_kernel_pick_pass.h
@@ -14,13 +14,65 @@
 
 #pragma once
 
+#include <limits>
 #include "paddle/fluid/lite/core/mir/pass.h"
+#include "paddle/fluid/lite/core/types.h"
 
 namespace paddle {
 namespace lite {
 namespace mir {
 
-class StaticKernelPickPass : public mir::Pass {};
+/*
+ * StaticKernelPickPass is a simple strategy for picking the kernel for each
+ * Operator using operator developer defined rule, there are many other tactics
+ * such as considering IO or kernel execution latency and we will implement them
+ * latter.
+ *
+ * There are two argument for this pass:
+ * - place, the target place.
+ * - kernel_pick_factors, the factors to consider in picking kernels.
+ * Set them first before execute the pass.
+ */
+class StaticKernelPickPass : public mir::InstructionPass {
+ public:
+  void Apply(std::unique_ptr<mir::SSAGraph>& graph) override;
+
+  const Place& place() const { return place_; }
+  const core::KernelPickFactor& kernel_pick_factors() const {
+    return kernel_pick_factors_;
+  }
+  core::KernelPickFactor* mutable_kernel_pick_factors() {
+    return &kernel_pick_factors_;
+  }
+
+ private:
+  // Score the kernel.
+  size_t KernelGrade(const lite::KernelBase& kernel) {
+    size_t score{};
+    const int kMax =
+        std::numeric_limits<core::KernelPickFactor::value_type>::max();
+    if (kernel_pick_factors_.IsTargetConsidered() &&
+        place().target == kernel.target()) {
+      score +=
+          kMax / static_cast<int>(core::KernelPickFactor::Factor::TargetFirst);
+    }
+    if (kernel_pick_factors_.IsPrecisionConsidered() &&
+        place().precision == kernel.precision()) {
+      score += kMax /
+               static_cast<int>(core::KernelPickFactor::Factor::PrecisionFirst);
+    }
+
+    // The data layout is not considered, for the input and output arguments
+    // might have different data layout.
+    // TODO(Superjomn) reconsider the idea of taking the data layout as a kernel
+    // specification.
+    return score;
+  }
+
+ private:
+  core::KernelPickFactor kernel_pick_factors_;
+  Place place_;
+};
 
 }  // namespace mir
 }  // namespace lite
diff --git a/paddle/fluid/lite/core/op_registry.h b/paddle/fluid/lite/core/op_registry.h
index be85cbe8419..95d62f2fee4 100644
--- a/paddle/fluid/lite/core/op_registry.h
+++ b/paddle/fluid/lite/core/op_registry.h
@@ -120,8 +120,10 @@ class KernelRegistor : public lite::Registor<KernelType> {
           LOG(INFO) << "Register kernel " << op_type << " for "
                     << TargetToStr(target) << " " << PrecisionToStr(precision);
           KernelRegistry::Global().Register<target, precision>(
-              op_type, [&]() -> std::unique_ptr<KernelType> {
-                return std::unique_ptr<KernelType>(new KernelType);
+              op_type, [&, op_type]() -> std::unique_ptr<KernelType> {
+                std::unique_ptr<KernelType> x(new KernelType);
+                x->set_op_type(op_type);
+                return x;
               });
         }) {}
 };
diff --git a/paddle/fluid/lite/core/optimizer.h b/paddle/fluid/lite/core/optimizer.h
index 76bfb6c7b38..dabe75f183a 100644
--- a/paddle/fluid/lite/core/optimizer.h
+++ b/paddle/fluid/lite/core/optimizer.h
@@ -16,7 +16,6 @@
 #include <string>
 #include <vector>
 #include "paddle/fluid/lite/core/mir/pass_manager.h"
-#include "paddle/fluid/lite/core/mir/pass_manager.h"
 #include "paddle/fluid/lite/core/mir/ssa_graph.h"
 
 namespace paddle {
@@ -28,17 +27,19 @@ namespace lite {
  */
 class Optimizer {
  public:
-  void Run(std::unique_ptr<mir::Program>&& program,
-           const std::vector<Place>& valid_places,
+  void Run(mir::Program&& program, const std::vector<Place>& valid_places,
            const std::vector<std::string>& passes = {}) {
     CHECK(!graph_) << "duplicate optimize found";
     graph_.reset(new mir::SSAGraph);
-    graph_->Build(*program, valid_places);
+    graph_->Build(program, valid_places);
     RunPasses();
   }
 
   // Generate a new program based on the mir graph.
-  std::unique_ptr<mir::Program> GenProgram() {}
+  std::unique_ptr<mir::Program> GenProgram() {
+    std::unique_ptr<mir::Program> res;
+    return res;
+  }
 
   // Generate C++ code which combines the inference program, model and weights.
   void GenCode(const std::string& code_dir);
@@ -50,7 +51,7 @@ class Optimizer {
 
  protected:
   // Run the default passes registered in the PassManager.
-  void RunPasses() { mir::PassManager::Global().Run(); }
+  void RunPasses() { mir::PassManager::Global().Run(graph_); }
 
   // Specify the passes and run them.
   void RunPasses(std::vector<std::string>& passes);
diff --git a/paddle/fluid/lite/core/types.h b/paddle/fluid/lite/core/types.h
index 52b5ea7d02a..990ffe0007b 100644
--- a/paddle/fluid/lite/core/types.h
+++ b/paddle/fluid/lite/core/types.h
@@ -25,6 +25,38 @@ using any_context_t = variant<Context<TARGET(kX86)>,  //
                               Context<TARGET(kCUDA)>  //
                               >;
 
+// Factors that impact the kernel picking strategy. Multiple factors can be
+// considered together by using statement like 'factor1 | factor2'
+class KernelPickFactor {
+ public:
+  using value_type = unsigned char;
+  enum class Factor : int {
+    // The following factors are sorted by priority.
+    TargetFirst = 1,
+    PrecisionFirst = 1 << 1,
+    DataLayoutFirst = 1 << 2,
+    DeviceFirst = 1 << 3,
+  };
+
+  // Has any factors considered.
+  bool AnyFactorConsidered() const { return data_; }
+
+  KernelPickFactor& ConsiderTarget();
+  KernelPickFactor& ConsiderPrecision();
+  KernelPickFactor& ConsiderDataLayout();
+  KernelPickFactor& ConsiderDevice();
+
+  bool IsTargetConsidered() const;
+  bool IsPrecisionConsidered() const;
+  bool IsDataLayoutConsidered() const;
+  bool IsDeviceConsidered() const {
+    return data_ & static_cast<int>(Factor::DeviceFirst);
+  }
+
+ private:
+  unsigned char data_{};
+};
+
 struct dim2 {
   int x{};
   int y{};
-- 
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