Use class unloading in dex2oat for verify and extract
Unload the main classloader in between each dex file compilation to
reduce RAM. This frees the whole java heap and associated linear
allocs. This is only used for quickening since filters that do
compilation may require loaded classes in the compiler and oat
writer.
This reduces dex2oat peak PSS for compiling a large app from 196MB
to 135MB.
Only works for verify and extract since the current approach is
incompatible with oat writer patching. b/63911263
Added a verification override that reads the compiled class status
to avoid ever verifying classes that were quickened (since this
is not supported and causes failures).
There is still some duplicated verification for some class with
superclasses in other dex files.
Support for quicken will be added in a follow up CL.
Bug: 63467744
Test: test-art-host
Test: test/testrunner/testrunner.py --interpreter --host -j40
Change-Id: Id0e4f84eb5db91d6143f752b498f4832a5b25b6e
diff --git a/compiler/image_writer.cc b/compiler/image_writer.cc
index 318009c..fc7cd01 100644
--- a/compiler/image_writer.cc
+++ b/compiler/image_writer.cc
@@ -894,7 +894,7 @@
&my_early_exit,
visited);
// Remove the class if the dex file is not in the set of dex files. This happens for classes that
- // are from uses library if there is no profile. b/30688277
+ // are from uses-library if there is no profile. b/30688277
mirror::DexCache* dex_cache = klass->GetDexCache();
if (dex_cache != nullptr) {
result = result ||
@@ -1153,9 +1153,22 @@
Thread* self = Thread::Current();
ScopedAssertNoThreadSuspension sa(__FUNCTION__);
- // Clear class table strong roots so that dex caches can get pruned. We require pruning the class
- // path dex caches.
- class_linker->ClearClassTableStrongRoots();
+ // Prune uses-library dex caches. Only prune the uses-library dex caches since we want to make
+ // sure the other ones don't get unloaded before the OatWriter runs.
+ class_linker->VisitClassTables(
+ [&](ClassTable* table) REQUIRES_SHARED(Locks::mutator_lock_) {
+ table->RemoveStrongRoots(
+ [&](GcRoot<mirror::Object> root) REQUIRES_SHARED(Locks::mutator_lock_) {
+ ObjPtr<mirror::Object> obj = root.Read();
+ if (obj->IsDexCache()) {
+ // Return true if the dex file is not one of the ones in the map.
+ return dex_file_oat_index_map_.find(obj->AsDexCache()->GetDexFile()) ==
+ dex_file_oat_index_map_.end();
+ }
+ // Return false to avoid removing.
+ return false;
+ });
+ });
// Remove the undesired classes from the class roots.
ObjPtr<mirror::ClassLoader> class_loader;