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1 /* Copyright 2017 The TensorFlow Authors. All Rights Reserved.
2 
3 Licensed under the Apache License, Version 2.0 (the "License");
4 you may not use this file except in compliance with the License.
5 You may obtain a copy of the License at
6 
7     http://www.apache.org/licenses/LICENSE-2.0
8 
9 Unless required by applicable law or agreed to in writing, software
10 distributed under the License is distributed on an "AS IS" BASIS,
11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 See the License for the specific language governing permissions and
13 limitations under the License.
14 ==============================================================================*/
15 
16 #ifndef TENSORFLOW_COMPILER_XLA_SERVICE_HLO_PASS_PIPELINE_H_
17 #define TENSORFLOW_COMPILER_XLA_SERVICE_HLO_PASS_PIPELINE_H_
18 
19 #include <algorithm>
20 #include <memory>
21 #include <string>
22 #include <vector>
23 
24 #include "absl/memory/memory.h"
25 #include "absl/strings/str_cat.h"
26 #include "tensorflow/compiler/xla/service/hlo_module.h"
27 #include "tensorflow/compiler/xla/service/hlo_pass_interface.h"
28 #include "tensorflow/compiler/xla/statusor.h"
29 #include "tensorflow/compiler/xla/types.h"
30 #include "tensorflow/core/platform/macros.h"
31 
32 namespace xla {
33 
34 // Pipeline of HLO passes.
35 class HloPassPipeline : public HloPassInterface {
36  public:
HloPassPipeline(const string & name)37   explicit HloPassPipeline(const string& name) : name_(name) {}
name()38   absl::string_view name() const override { return name_; }
39 
40   // Add a pass to the pipeline. It should be called with the arguments for the
41   // pass constructor:
42   //
43   //   pipeline.AddPass<FooPass>(constructor_arg1, constructor_arg2);
44   //
45   // Returns a reference to the added pass.
46   template <typename T, typename... Args>
AddPass(Args &&...args)47   T& AddPass(Args&&... args) {
48     CHECK(!run_called_) << "AddPass cannot be called after Run";
49     auto pass = new T(std::forward<Args>(args)...);
50     passes_.push_back(std::unique_ptr<T>(pass));
51     return *pass;
52   }
53 
54   // Add an invariant-checking pass to the pipeline. It will be run before and
55   // after each HLO pass. The invariant checking pass must not mutate the graph
56   // (it is required to always return "false" from its Run() method).
57   template <typename T, typename... Args>
AddInvariantChecker(Args &&...args)58   T& AddInvariantChecker(Args&&... args) {
59     CHECK(!run_called_) << "AddInvariantChecker cannot be called after Run";
60     auto pass = new T(std::forward<Args>(args)...);
61     invariant_checkers_.push_back(std::unique_ptr<T>(pass));
62     return *pass;
63   }
64 
65   StatusOr<bool> Run(HloModule* module) override;
66   StatusOr<bool> RunOnModuleGroup(HloModuleGroup* module_group) override;
67 
68  private:
69   // Returns the set of passes which are enabled. DebugOptions can selectively
70   // disable passes via --xla_disable_hlo_passes flag.
71   std::vector<HloPassInterface*> GetEnabledPasses(
72       const DebugOptions& debug_options);
73 
74   // Maybe dumps the given module or module group depending on flag values
75   // contained in DebugOptions of module config.
76   void MaybeDumpHlo(const HloModuleGroup& module_group,
77                     absl::string_view after_pass_name,
78                     absl::string_view before_pass_name);
79   void MaybeDumpHlo(const HloModule& module, absl::string_view after_pass_name,
80                     absl::string_view before_pass_name);
81 
82   // Runs the invariant checker on the given HLO. HloT can be either HloModule
83   // or HloModuleGroup.
84   template <typename HloT>
85   Status RunInvariantCheckers(HloT* hlo, absl::string_view after_pass_name);
86 
87   // Helper which runs the given pass on the given HLO. HloT can be either
88   // HloModule or HloModuleGroup.
89   template <typename HloT>
90   StatusOr<bool> RunPassesInternal(HloT* hlo,
91                                    absl::Span<HloPassInterface* const> passes);
92 
93   // Helpers which run the given passes on the given HLO construct. These
94   // helpers enable templating of the core of the pipeline logic by providing
95   // HloModule and HloModuleGroup specific methods with the same name.
RunHelper(HloPassInterface * pass,HloModule * module)96   static StatusOr<bool> RunHelper(HloPassInterface* pass, HloModule* module) {
97     return pass->Run(module);
98   }
RunHelper(HloPassInterface * pass,HloModuleGroup * module_group)99   static StatusOr<bool> RunHelper(HloPassInterface* pass,
100                                   HloModuleGroup* module_group) {
101     return pass->RunOnModuleGroup(module_group);
102   }
103 
104   const string name_;
105   std::vector<std::unique_ptr<HloPassInterface>> passes_;
106   std::vector<std::unique_ptr<HloPassInterface>> invariant_checkers_;
107   bool run_called_ = false;
108 };
109 
110 }  // namespace xla
111 
112 #endif  // TENSORFLOW_COMPILER_XLA_SERVICE_HLO_PASS_PIPELINE_H_
113