Revert "Always use an array in the DexCache for ArtField and ArtMethod."

This reverts commit 1f9c184392020cb5c4bdf453f4c8847ca389614b.

Reason for revert: Memory regressions.

Change-Id: I85357603c31aa7dbde92aea5958167ea8f0fd481

4 files changed, 5 insertions, 55 deletions

diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 6d247a6d7a..eb9e9062cb 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -10994,24 +10994,8 @@ void ClassLinker::InsertDexFileInToClassLoader(ObjPtr<mirror::Object> dex_file,
   }
 }
 
-class ReclaimMemoryDexCacheVisitor : public DexCacheVisitor {
- public:
-  ReclaimMemoryDexCacheVisitor() {}
-
-  void Visit(ObjPtr<mirror::DexCache> dex_cache)
-      REQUIRES_SHARED(Locks::dex_lock_, Locks::mutator_lock_) override {
-    dex_cache->ReclaimMemory();
-  }
-};
-
 void ClassLinker::CleanupClassLoaders() {
   Thread* const self = Thread::Current();
-  // We clear dex cache arrays for every GC.
-  {
-    ReaderMutexLock mu(self, *Locks::dex_lock_);
-    ReclaimMemoryDexCacheVisitor visitor;
-    VisitDexCaches(&visitor);
-  }
   std::list<ClassLoaderData> to_delete;
   // Do the delete outside the lock to avoid lock violation in jit code cache.
   {
diff --git a/runtime/mirror/dex_cache.cc b/runtime/mirror/dex_cache.cc
index abbd23442b..b981f08d97 100644
--- a/runtime/mirror/dex_cache.cc
+++ b/runtime/mirror/dex_cache.cc
@@ -224,6 +224,7 @@ void DexCache::SetResolvedType(dex::TypeIndex type_idx, ObjPtr<Class> resolved)
   SetResolvedTypesEntry(type_idx.index_, resolved.Ptr());
   // TODO: Fine-grained marking, so that we don't need to go through all arrays in full.
   WriteBarrier::ForEveryFieldWrite(this);
+
   if (this == resolved->GetDexCache()) {
     // If we're updating the dex cache of the class, optimistically update the cache for methods and
     // fields if the caches are full arrays.
@@ -254,36 +255,5 @@ void DexCache::SetResolvedType(dex::TypeIndex type_idx, ObjPtr<Class> resolved)
   }
 }
 
-static void ReclaimMemoryInternal(uint64_t address, size_t size) {
-  if (address == 0u || size <= MemMap::GetPageSize()) {
-    return;
-  }
-  uint8_t* const mem_begin = reinterpret_cast<uint8_t*>(address);
-  uint8_t* const mem_end = reinterpret_cast<uint8_t*>(address + size);
-  uint8_t* const page_begin = AlignUp(mem_begin, MemMap::GetPageSize());
-  uint8_t* const page_end = AlignDown(mem_end, MemMap::GetPageSize());
-  DCHECK_GE(page_end, page_begin);
-  if (page_end == page_begin) {
-    return;
-  }
-  bool res = madvise(page_begin, page_end - page_begin, MADV_DONTNEED);
-  if (res == -1) {
-    PLOG(WARNING) << "madvise failed";
-  }
-}
-
-void DexCache::ReclaimMemory() {
-  ReclaimMemoryInternal(resolved_fields_array_,
-                        NumResolvedFieldsArray() * sizeof(ArtField*));
-  ReclaimMemoryInternal(resolved_method_types_array_,
-                        NumResolvedMethodTypesArray() * sizeof(GcRoot<mirror::MethodType>));
-  ReclaimMemoryInternal(resolved_methods_array_,
-                        NumResolvedMethodsArray() * sizeof(ArtMethod*));
-  ReclaimMemoryInternal(resolved_types_array_,
-                        NumResolvedTypesArray() * sizeof(GcRoot<mirror::Class>));
-  ReclaimMemoryInternal(strings_array_,
-                        NumStringsArray() * sizeof(GcRoot<mirror::String>));
-}
-
 }  // namespace mirror
 }  // namespace art
diff --git a/runtime/mirror/dex_cache.h b/runtime/mirror/dex_cache.h
index 69e610d9dc..c1d8cd8335 100644
--- a/runtime/mirror/dex_cache.h
+++ b/runtime/mirror/dex_cache.h
@@ -274,14 +274,12 @@ class MANAGED DexCache final : public Object {
                 "String dex cache size is not a power of 2.");
 
   // Size of field dex cache. Needs to be a power of 2 for entrypoint assumptions to hold.
-  // Set to the maximum number of field IDs to always use a direct array.
-  static constexpr size_t kDexCacheFieldCacheSize = 65536;
+  static constexpr size_t kDexCacheFieldCacheSize = 1024;
   static_assert(IsPowerOfTwo(kDexCacheFieldCacheSize),
                 "Field dex cache size is not a power of 2.");
 
   // Size of method dex cache. Needs to be a power of 2 for entrypoint assumptions to hold.
-  // Set to the maximum number of method IDs to always use a direct array.
-  static constexpr size_t kDexCacheMethodCacheSize = 65536;
+  static constexpr size_t kDexCacheMethodCacheSize = 1024;
   static_assert(IsPowerOfTwo(kDexCacheMethodCacheSize),
                 "Method dex cache size is not a power of 2.");
 
@@ -394,8 +392,6 @@ class MANAGED DexCache final : public Object {
     return number_of_elements <= dex_cache_size;
   }
 
-  // Returns to the OS memory used for dex cache arrays.
-  void ReclaimMemory() REQUIRES_SHARED(Locks::mutator_lock_);
 
 // NOLINTBEGIN(bugprone-macro-parentheses)
 #define DEFINE_ARRAY(name, array_kind, getter_setter, type, ids, alloc_kind) \
diff --git a/runtime/oat/image.cc b/runtime/oat/image.cc
index 77eb7df6e6..b62a4e0621 100644
--- a/runtime/oat/image.cc
+++ b/runtime/oat/image.cc
@@ -34,8 +34,8 @@
 namespace art HIDDEN {
 
 const uint8_t ImageHeader::kImageMagic[] = { 'a', 'r', 't', '\n' };
-// Last change: Add kAccDefault as an intrinsic bit.
-const uint8_t ImageHeader::kImageVersion[] = { '1', '1', '7', '\0' };
+// Revert dex cache change.
+const uint8_t ImageHeader::kImageVersion[] = { '1', '1', '8', '\0' };
 
 ImageHeader::ImageHeader(uint32_t image_reservation_size,
                          uint32_t component_count,