Optimize suspend checks in optimizing compiler.

- Remove the ones added during graph build (they were added
  for the baseline code generator).
- Emit them at loop back edges after phi moves, so that the test
  can directly jump to the loop header.
- Fix x86 and x86_64 suspend check by using cmpw instead of cmpl.

Change-Id: I6fad5795a55705d86c9e1cb85bf5d63dadfafa2a

1 files changed, 41 insertions, 0 deletions

diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc
new file mode 100644
index 0000000000..a0de73da32
--- /dev/null
+++ b/compiler/optimizing/instruction_simplifier.cc
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#include "instruction_simplifier.h"
+
+namespace art {
+
+void InstructionSimplifier::Run() {
+  VisitInsertionOrder();
+}
+
+void InstructionSimplifier::VisitSuspendCheck(HSuspendCheck* check) {
+  HBasicBlock* block = check->GetBlock();
+  // Currently always keep the suspend check at entry.
+  if (block->IsEntryBlock()) return;
+
+  // Currently always keep suspend checks at loop entry.
+  if (block->IsLoopHeader() && block->GetFirstInstruction() == check) {
+    DCHECK(block->GetLoopInformation()->GetSuspendCheck() == check);
+    return;
+  }
+
+  // Remove the suspend check that was added at build time for the baseline
+  // compiler.
+  block->RemoveInstruction(check);
+}
+
+}  // namespace art