ARM64: Instruction simplification for array accesses.
HArrayGet and HArraySet with variable indexes generate two
instructions on arm64, like
add temp, obj, #data_offset
ldr out, [temp, index LSL #shift_amount]
When we have multiple accesses to the same array, the initial `add`
instruction is redundant.
This patch introduces the first instruction simplification in the
arm64-specific instruction simplification pass. It splits HArrayGet
and HArraySet using the new arm64-specific IR HIntermediateAddress.
After that we run GVN again to squash the multiple occurrences of
HIntermediateAddress.
Change-Id: I2e3d12fbb07fed07b2cb2f3f47f99f5a032f8312
diff --git a/compiler/optimizing/nodes_arm64.h b/compiler/optimizing/nodes_arm64.h
new file mode 100644
index 0000000..885d3a2
--- /dev/null
+++ b/compiler/optimizing/nodes_arm64.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2015 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_NODES_ARM64_H_
+#define ART_COMPILER_OPTIMIZING_NODES_ARM64_H_
+
+namespace art {
+
+// This instruction computes an intermediate address pointing in the 'middle' of an object. The
+// result pointer cannot be handled by GC, so extra care is taken to make sure that this value is
+// never used across anything that can trigger GC.
+class HArm64IntermediateAddress : public HExpression<2> {
+ public:
+ HArm64IntermediateAddress(HInstruction* base_address, HInstruction* offset, uint32_t dex_pc)
+ : HExpression(Primitive::kPrimNot, SideEffects::DependsOnGC(), dex_pc) {
+ SetRawInputAt(0, base_address);
+ SetRawInputAt(1, offset);
+ }
+
+ bool CanBeMoved() const OVERRIDE { return true; }
+ bool InstructionDataEquals(HInstruction* other ATTRIBUTE_UNUSED) const OVERRIDE { return true; }
+
+ HInstruction* GetBaseAddress() const { return InputAt(0); }
+ HInstruction* GetOffset() const { return InputAt(1); }
+
+ DECLARE_INSTRUCTION(Arm64IntermediateAddress);
+
+ private:
+ DISALLOW_COPY_AND_ASSIGN(HArm64IntermediateAddress);
+};
+
+} // namespace art
+
+#endif // ART_COMPILER_OPTIMIZING_NODES_ARM64_H_