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/dex2oat/dex2oat.cc b/dex2oat/dex2oat.cc
index 5333128..dfcb4bc 100644
--- a/dex2oat/dex2oat.cc
+++ b/dex2oat/dex2oat.cc
@@ -217,7 +217,7 @@
UsageError(" --image=<file.art>: specifies an output image filename.");
UsageError(" Example: --image=/system/framework/boot.art");
UsageError("");
- UsageError(" --image-format=(uncompressed|lz4):");
+ UsageError(" --image-format=(uncompressed|lz4|lz4hc):");
UsageError(" Which format to store the image.");
UsageError(" Example: --image-format=lz4");
UsageError(" Default: uncompressed");
@@ -681,6 +681,8 @@
const StringPiece format_str = option.substr(substr.length());
if (format_str == "lz4") {
image_storage_mode_ = ImageHeader::kStorageModeLZ4;
+ } else if (format_str == "lz4hc") {
+ image_storage_mode_ = ImageHeader::kStorageModeLZ4HC;
} else if (format_str == "uncompressed") {
image_storage_mode_ = ImageHeader::kStorageModeUncompressed;
} else {