[exo] Fuse Rsqrt (#8655)

This commit introduces a pass to fuse Rsqrt pattern

Signed-off-by: Cheongyo Bahk <ch.bahk@samsung.com>

diff --git a/compiler/exo/src/Pass/FuseRsqrtPass.cpp b/compiler/exo/src/Pass/FuseRsqrtPass.cpp
new file mode 100644 (file)
index 0000000..5cea44d
--- /dev/null
+++ b/compiler/exo/src/Pass/FuseRsqrtPass.cpp
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2019 Samsung Electronics Co., Ltd. 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.
+ */
+
+#include "FuseRsqrtPass.h"
+
+#include "Check.h"
+
+#include "Dialect/IR/TFLNodes.h"
+
+#include <loco/IR/Nodes.h>
+
+namespace
+{
+
+/**
+ * @return  Casted TFLDiv for fusable candidate, nullptr otherwise
+ *
+ * This helper checkes fusability with following conditions:
+ * - TFLDiv has no activation
+ * - TFLDiv's first argument is TFLConst with all value 1
+ * - TFLDiv's second argument is TFLSqrt
+ */
+locoex::TFLDiv *as_candidate(loco::Node *node)
+{
+  auto div = dynamic_cast<locoex::TFLDiv *>(node);
+  if (not div)
+    return nullptr;
+
+  // Cannot fuse Div with activation function
+  if (div->fusedActivationFunction() != locoex::FusedActFunc::NONE)
+    return nullptr;
+
+  auto const_one = dynamic_cast<locoex::TFLConst *>(div->x());
+  if (not const_one)
+    return nullptr;
+
+  const loco::DataType FLOAT32 = loco::DataType::FLOAT32;
+  // TODO Support other dtype
+  EXO_ASSERT(const_one->dtype() == FLOAT32, "Only support FLOAT32 now");
+  for (uint32_t i = 0; i < const_one->size<FLOAT32>(); ++i)
+    if (const_one->at<FLOAT32>(i) != 1.0f)
+      return nullptr;
+
+  auto sqrt = dynamic_cast<locoex::TFLSqrt *>(div->y());
+  if (not sqrt)
+    return nullptr;
+
+  return div;
+}
+
+void fuse_rsqrt(locoex::TFLDiv *div)
+{
+  auto sqrt = dynamic_cast<locoex::TFLSqrt *>(div->y());
+  EXO_ASSERT(sqrt, "sqrt should be valid at this point");
+
+  // TFLRsqrt to replace
+  auto rsqrt = div->graph()->nodes()->create<locoex::TFLRsqrt>();
+  rsqrt->x(sqrt->x());
+
+  // replace
+  loco::replace(div).with(rsqrt);
+}
+
+} // namespace
+
+namespace exo
+{
+
+bool FuseRsqrtPass::run(loco::Graph *g)
+{
+  bool changed = false;
+  for (auto node : loco::active_nodes(loco::output_nodes(g)))
+  {
+    if (auto div = as_candidate(node))
+    {
+      fuse_rsqrt(div);
+      changed = true;
+    }
+  }
+
+  return changed;
+}
+
+} // namespace exo

diff --git a/compiler/exo/src/Pass/FuseRsqrtPass.h b/compiler/exo/src/Pass/FuseRsqrtPass.h
new file mode 100644 (file)
index 0000000..1e60e4a
--- /dev/null
+++ b/compiler/exo/src/Pass/FuseRsqrtPass.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2019 Samsung Electronics Co., Ltd. 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 __FUSE_RSQRT_PASS_H__
+#define __FUSE_RSQRT_PASS_H__
+
+#include <logo/Pass.h>
+
+namespace exo
+{
+
+/**
+ * @brief Class to fuse TFLSqrt that is divided(TFLDiv) by 1, into TFLRsqrt
+ *
+ * <BEFORE>
+ *
+ *    TFLConst(1) ------
+ *                      \
+ *    A --- TFLSqrt --- TFLDiv --- B
+ *
+ * <AFTER>
+ *
+ *    A --- TFLRsqrt --- B
+ */
+struct FuseRsqrtPass final : public logo::Pass
+{
+  const char *name(void) const final { return "exo::FuseRsqrtPass"; }
+
+  bool run(loco::Graph *g) final;
+};
+
+} // namespace exo
+
+#endif // __FUSE_RSQRT_PASS_H__