[XLA] Create CallInliner HLO pass to recursively force-inline kCall operations.

PiperOrigin-RevId: 163436255

1 files changed, 48 insertions, 0 deletions

diff --git a/tensorflow/compiler/xla/service/call_inliner.h b/tensorflow/compiler/xla/service/call_inliner.h
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+++ b/tensorflow/compiler/xla/service/call_inliner.h
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+/* Copyright 2017 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+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.
+==============================================================================*/
+
+#ifndef TENSORFLOW_COMPILER_XLA_SERVICE__CALL_INLINER_H_
+#define TENSORFLOW_COMPILER_XLA_SERVICE__CALL_INLINER_H_
+
+#include <deque>
+
+#include "tensorflow/compiler/xla/service/hlo_pass_interface.h"
+#include "tensorflow/compiler/xla/statusor.h"
+
+namespace xla {
+
+// For every kCall operation in the main computation, we inline the body of the
+// called function, and proceed recursively.
+class CallInliner : public HloPassInterface {
+ public:
+  ~CallInliner() override = default;
+  tensorflow::StringPiece name() const override { return "CallInliner"; }
+
+  StatusOr<bool> Run(HloModule* module) override;
+
+ private:
+  // Replaces the given call operation -- which must be an operation inside the
+  // entry computation with opcode kCall -- with the called computation's body,
+  // such that the called computation is inline in the entry computation.
+  //
+  // On successful inlining, the inlined computation may have itself contained
+  // calls; if so, they are added to the work_queue.
+  Status ReplaceWithInlinedBody(HloInstruction* call,
+                                std::deque<HloInstruction*>* work_queue);
+};
+
+}  // namespace xla
+
+#endif  // TENSORFLOW_COMPILER_XLA_SERVICE__CALL_INLINER_H_