creating workflow for mirror::String compression

All-ASCII String characters are stored in 8-bit blocks
instead of 16-bit. The compression has not taken place, but all
workflow are in the code already (changing kUseStringCompression in
string.h file to TRUE will enable the feature)

Notes: Feature works on interpreter only without optimizing

Test art: m ART_TEST_INTERPRETER=true ART_TEST_OPTIMIZING=false
          test-art-host

Also tested with String tests from libcore/:
1. libcore.java.lang.StringTest
2. libcore.java.lang.StringBufferTest
3. libcore.java.lang.StringBuilderTest
4. libcore.java.lang.OldStringTest
5. libcore.java.lang.OldStringBufferTest

Memory improvement is 33% (from 6.03% to 4.03%, total String memory
from all apps per total memory of all apps) measured on Angler
with Hprof tools

Bug: 31040547
Change-Id: I9cc92c265ebf1305fc06b5fc33efd83797660cce

1 files changed, 4 insertions, 2 deletions

diff --git a/compiler/image_test.cc b/compiler/image_test.cc
index 91579e9daf..e1ee0d2966 100644
--- a/compiler/image_test.cc
+++ b/compiler/image_test.cc
@@ -188,6 +188,7 @@ void ImageTest::TestWriteRead(ImageHeader::StorageMode storage_mode) {
   }
 
   uint64_t image_file_size;
+  size_t image_size;
   {
     std::unique_ptr<File> file(OS::OpenFileForReading(image_file.GetFilename().c_str()));
     ASSERT_TRUE(file.get() != nullptr);
@@ -206,6 +207,7 @@ void ImageTest::TestWriteRead(ImageHeader::StorageMode storage_mode) {
     ASSERT_TRUE(space->IsMallocSpace());
 
     image_file_size = file->GetLength();
+    image_size = image_header.GetImageSize();
   }
 
   ASSERT_TRUE(compiler_driver_->GetImageClasses() != nullptr);
@@ -255,10 +257,10 @@ void ImageTest::TestWriteRead(ImageHeader::StorageMode storage_mode) {
   ASSERT_TRUE(image_space != nullptr);
   if (storage_mode == ImageHeader::kStorageModeUncompressed) {
     // Uncompressed, image should be smaller than file.
-    ASSERT_LE(image_space->Size(), image_file_size);
+    ASSERT_LE(image_size, image_file_size);
   } else {
     // Compressed, file should be smaller than image.
-    ASSERT_LE(image_file_size, image_space->Size());
+    ASSERT_LE(image_file_size, image_size);
   }
 
   image_space->VerifyImageAllocations();