Remove alignment bits in between stack maps
Saves 0.65% of boot.oat size, probably similar on apps. Added
BitMemoryRegion to avoid requiring adding state to StackMap. Added
test to memory_region_test.
Test: clean-oat-host && test-art-host
Bug: 34621054
Change-Id: I40279c59e262bd5e3c6a9135f83e22b5b6900d68
diff --git a/runtime/bit_memory_region.h b/runtime/bit_memory_region.h
new file mode 100644
index 0000000..90a1981
--- /dev/null
+++ b/runtime/bit_memory_region.h
@@ -0,0 +1,69 @@
+/*
+ * 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_RUNTIME_BIT_MEMORY_REGION_H_
+#define ART_RUNTIME_BIT_MEMORY_REGION_H_
+
+#include "memory_region.h"
+
+namespace art {
+
+// Bit memory region is a bit offset subregion of a normal memoryregion. This is useful for
+// abstracting away the bit start offset to avoid needing passing as an argument everywhere.
+class BitMemoryRegion FINAL : public ValueObject {
+ public:
+ BitMemoryRegion() = default;
+ BitMemoryRegion(MemoryRegion region, size_t bit_offset, size_t bit_size) {
+ bit_start_ = bit_offset % kBitsPerByte;
+ const size_t start = bit_offset / kBitsPerByte;
+ const size_t end = (bit_offset + bit_size + kBitsPerByte - 1) / kBitsPerByte;
+ region_ = region.Subregion(start, end - start);
+ }
+
+ void* pointer() const { return region_.pointer(); }
+ size_t size() const { return region_.size(); }
+ size_t BitOffset() const { return bit_start_; }
+ size_t size_in_bits() const {
+ return region_.size_in_bits();
+ }
+
+ // Load a single bit in the region. The bit at offset 0 is the least
+ // significant bit in the first byte.
+ ALWAYS_INLINE bool LoadBit(uintptr_t bit_offset) const {
+ return region_.LoadBit(bit_offset + bit_start_);
+ }
+
+ ALWAYS_INLINE void StoreBit(uintptr_t bit_offset, bool value) const {
+ region_.StoreBit(bit_offset + bit_start_, value);
+ }
+
+ ALWAYS_INLINE uint32_t LoadBits(uintptr_t bit_offset, size_t length) const {
+ return region_.LoadBits(bit_offset + bit_start_, length);
+ }
+
+ // Store at a bit offset from inside the bit memory region.
+ ALWAYS_INLINE void StoreBits(uintptr_t bit_offset, uint32_t value, size_t length) {
+ region_.StoreBits(bit_offset + bit_start_, value, length);
+ }
+
+ private:
+ MemoryRegion region_;
+ size_t bit_start_ = 0;
+};
+
+} // namespace art
+
+#endif // ART_RUNTIME_BIT_MEMORY_REGION_H_