[XLA] Make `HloPass` an interface, NFC

This will allow inheritance from both `HloPassInterface` and `DfsHloVisitor`, so various passes which include a visitor can have handler methods overridden per backend.
Change: 145477041

1 files changed, 47 insertions, 0 deletions

diff --git a/tensorflow/compiler/xla/service/hlo_pass_fix.h b/tensorflow/compiler/xla/service/hlo_pass_fix.h
new file mode 100644
index 0000000000..b3d0a07add
--- /dev/null
+++ b/tensorflow/compiler/xla/service/hlo_pass_fix.h
@@ -0,0 +1,47 @@
+/* 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_HLO_PASS_FIX_H_
+#define TENSORFLOW_COMPILER_XLA_SERVICE_HLO_PASS_FIX_H_
+
+#include "tensorflow/compiler/xla/service/hlo_module.h"
+#include "tensorflow/compiler/xla/status_macros.h"
+#include "tensorflow/compiler/xla/statusor.h"
+#include "tensorflow/compiler/xla/types.h"
+#include "tensorflow/core/platform/macros.h"
+
+namespace xla {
+
+// Do an HLO pass to a fix point.
+template <typename Pass>
+class HloPassFix : public Pass {
+ public:
+  template <typename... Args>
+  explicit HloPassFix(Args&&... args) : Pass(args...) {}
+
+  StatusOr<bool> Run(HloModule* module) override {
+    bool changed = false;
+    bool changed_this_iteration = true;
+    while (changed_this_iteration) {
+      TF_ASSIGN_OR_RETURN(changed_this_iteration, Pass::Run(module));
+      changed |= changed_this_iteration;
+    }
+    return changed;
+  }
+};
+
+}  // namespace xla
+
+#endif  // TENSORFLOW_COMPILER_XLA_SERVICE_HLO_PASS_FIX_H_