Implement code sinking.

Small example of what the optimization does:

Object o = new Object();
if (test) {
  throw new Error(o.toString());
}

will be turned into (note that the first user of 'o'
is the 'new Error' allocation which has 'o' in its
environment):
if (test) {
  Object o = new Obect();
  throw new Error(o.toString());
}

There are other examples in 639-checker-code-sinking.

Ritz individual benchmarks improve on art-jit-cc from
5% (EvaluateComplexFormulas) to 23% (MoveFunctionColumn)
on all platforms.

Test: 639-checker-code-sinking
Test: test-art-host
Test: borg job run
Test: libcore + jdwp

bug:35634932
bug:30933338

Change-Id: Ib99c00c93fe76ffffb17afffb5a0e30a14310652

1 files changed, 48 insertions, 0 deletions

diff --git a/compiler/optimizing/code_sinking.h b/compiler/optimizing/code_sinking.h
new file mode 100644
index 0000000000..59cda52a8c
--- /dev/null
+++ b/compiler/optimizing/code_sinking.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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 ART_COMPILER_OPTIMIZING_CODE_SINKING_H_
+#define ART_COMPILER_OPTIMIZING_CODE_SINKING_H_
+
+#include "nodes.h"
+#include "optimization.h"
+
+namespace art {
+
+/**
+ * Optimization pass to move instructions into uncommon branches,
+ * when it is safe to do so.
+ */
+class CodeSinking : public HOptimization {
+ public:
+  CodeSinking(HGraph* graph, OptimizingCompilerStats* stats)
+      : HOptimization(graph, kCodeSinkingPassName, stats) {}
+
+  void Run() OVERRIDE;
+
+  static constexpr const char* kCodeSinkingPassName = "code_sinking";
+
+ private:
+  // Try to move code only used by `end_block` and all its post-dominated / dominated
+  // blocks, to these blocks.
+  void SinkCodeToUncommonBranch(HBasicBlock* end_block);
+
+  DISALLOW_COPY_AND_ASSIGN(CodeSinking);
+};
+
+}  // namespace art
+
+#endif  // ART_COMPILER_OPTIMIZING_CODE_SINKING_H_