Add lz4hc image compression format
Smaller than lz4 and decompresses at the same speed. Compression is
a bit slower.
Example saves on old FB APK:
Uncompressed: 44748800 bytes
LZ4: 12443648 bytes
LZ4HC: 11055104 bytes
Generating the image slows down by ~1s per 20MB of image due to
slower compression. Decompression is about the same speed but there
should be a slight speedup since less data needs to be read from
flash.
Added test.
Bug: 22858531
Change-Id: Ib2704305b9bec5b0ba3b1e871f59f4eedff330b7
diff --git a/runtime/gc/space/image_space.cc b/runtime/gc/space/image_space.cc
index bc21b33..4ef36a4 100644
--- a/runtime/gc/space/image_space.cc
+++ b/runtime/gc/space/image_space.cc
@@ -1252,7 +1252,8 @@
// Only care about the error message for the last address in addresses. We want to avoid the
// overhead of printing the process maps if we can relocate.
std::string* out_error_msg = (address == addresses.back()) ? &temp_error_msg : nullptr;
- if (image_header->GetStorageMode() == ImageHeader::kStorageModeUncompressed) {
+ const ImageHeader::StorageMode storage_mode = image_header->GetStorageMode();
+ if (storage_mode == ImageHeader::kStorageModeUncompressed) {
map.reset(MemMap::MapFileAtAddress(address,
image_header->GetImageSize(),
PROT_READ | PROT_WRITE,
@@ -1264,6 +1265,12 @@
image_filename,
/*out*/out_error_msg));
} else {
+ if (storage_mode != ImageHeader::kStorageModeLZ4 &&
+ storage_mode != ImageHeader::kStorageModeLZ4HC) {
+ *error_msg = StringPrintf("Invalid storage mode in image header %d",
+ static_cast<int>(storage_mode));
+ return nullptr;
+ }
// Reserve output and decompress into it.
map.reset(MemMap::MapAnonymous(image_location,
address,
@@ -1289,6 +1296,7 @@
}
memcpy(map->Begin(), image_header, sizeof(ImageHeader));
const uint64_t start = NanoTime();
+ // LZ4HC and LZ4 have same internal format, both use LZ4_decompress.
TimingLogger::ScopedTiming timing2("LZ4 decompress image", &logger);
const size_t decompressed_size = LZ4_decompress_safe(
reinterpret_cast<char*>(temp_map->Begin()) + sizeof(ImageHeader),