Address some comments in image writer
Change-Id: I74c3192d595dc8b86d6ce3e3ca3bb32cce61872c
diff --git a/compiler/image_writer.cc b/compiler/image_writer.cc
index f9f0eb8..fce08ea 100644
--- a/compiler/image_writer.cc
+++ b/compiler/image_writer.cc
@@ -1221,8 +1221,11 @@
// Compiling the boot image, add null class loader.
class_loaders_.insert(nullptr);
}
- if (!class_loaders_.empty()) {
- CHECK_EQ(class_loaders_.size(), 1u) << "Should only have one real class loader in the image";
+ // class_loaders_ usually will not be empty, but may be empty if we attempt to create an image
+ // with no classes.
+ if (class_loaders_.size() == 1u) {
+ // Only write the class table if we have exactly one class loader. There may be cases where
+ // there are multiple class loaders if a class path is passed to dex2oat.
ReaderMutexLock mu(Thread::Current(), *Locks::classlinker_classes_lock_);
for (mirror::ClassLoader* loader : class_loaders_) {
ClassTable* table = class_linker->ClassTableForClassLoader(loader);
@@ -1424,28 +1427,32 @@
CHECK_EQ(temp_intern_table.Size(), intern_table->Size());
temp_intern_table.VisitRoots(&root_visitor, kVisitRootFlagAllRoots);
- // Write the class table(s) into the image.
- ClassLinker* const class_linker = runtime->GetClassLinker();
- const ImageSection& class_table_section = image_header->GetImageSection(
- ImageHeader::kSectionClassTable);
- uint8_t* const class_table_memory_ptr = image_->Begin() + class_table_section.Offset();
- ReaderMutexLock mu(Thread::Current(), *Locks::classlinker_classes_lock_);
- size_t class_table_bytes = 0;
- for (mirror::ClassLoader* loader : class_loaders_) {
- ClassTable* table = class_linker->ClassTableForClassLoader(loader);
- CHECK(table != nullptr);
- uint8_t* memory_ptr = class_table_memory_ptr + class_table_bytes;
- class_table_bytes += table->WriteToMemory(memory_ptr);
- // Fixup the pointers in the newly written class table to contain image addresses. See
- // above comment for intern tables.
- ClassTable temp_class_table;
- temp_class_table.ReadFromMemory(memory_ptr);
- // CHECK_EQ(temp_class_table.NumNonZygoteClasses(), table->NumNonZygoteClasses());
- BufferedRootVisitor<kDefaultBufferedRootCount> buffered_visitor(&root_visitor,
- RootInfo(kRootUnknown));
- temp_class_table.VisitRoots(buffered_visitor);
+ // Write the class table(s) into the image. class_table_bytes_ may be 0 if there are multiple
+ // class loaders. Writing multiple class tables into the image is currently unsupported.
+ if (class_table_bytes_ > 0u) {
+ ClassLinker* const class_linker = runtime->GetClassLinker();
+ const ImageSection& class_table_section = image_header->GetImageSection(
+ ImageHeader::kSectionClassTable);
+ uint8_t* const class_table_memory_ptr = image_->Begin() + class_table_section.Offset();
+ ReaderMutexLock mu(Thread::Current(), *Locks::classlinker_classes_lock_);
+ size_t class_table_bytes = 0;
+ for (mirror::ClassLoader* loader : class_loaders_) {
+ ClassTable* table = class_linker->ClassTableForClassLoader(loader);
+ CHECK(table != nullptr);
+ uint8_t* memory_ptr = class_table_memory_ptr + class_table_bytes;
+ class_table_bytes += table->WriteToMemory(memory_ptr);
+ // Fixup the pointers in the newly written class table to contain image addresses. See
+ // above comment for intern tables.
+ ClassTable temp_class_table;
+ temp_class_table.ReadFromMemory(memory_ptr);
+ CHECK_EQ(temp_class_table.NumZygoteClasses(), table->NumNonZygoteClasses() +
+ table->NumZygoteClasses());
+ BufferedRootVisitor<kDefaultBufferedRootCount> buffered_visitor(&root_visitor,
+ RootInfo(kRootUnknown));
+ temp_class_table.VisitRoots(buffered_visitor);
+ }
+ CHECK_EQ(class_table_bytes, class_table_bytes_);
}
- CHECK_EQ(class_table_bytes, class_table_bytes_);
}
void ImageWriter::CopyAndFixupObjects() {
diff --git a/compiler/image_writer.h b/compiler/image_writer.h
index c20d836..8e930f0 100644
--- a/compiler/image_writer.h
+++ b/compiler/image_writer.h
@@ -457,7 +457,9 @@
// Prune class memoization table to speed up ContainsBootClassLoaderNonImageClass.
std::unordered_map<mirror::Class*, bool> prune_class_memo_;
- // Class loaders with a class table to write out. Should only be one currently.
+ // Class loaders with a class table to write out. There should only be one class loader because
+ // dex2oat loads the dex files to be compiled into a single class loader. For the boot image,
+ // null is a valid entry.
std::unordered_set<mirror::ClassLoader*> class_loaders_;
// Number of image class table bytes.
diff --git a/runtime/image.h b/runtime/image.h
index 3032beb..7418f66 100644
--- a/runtime/image.h
+++ b/runtime/image.h
@@ -262,7 +262,7 @@
// Boolean (0 or 1) to denote if the image was compiled with --compile-pic option
const uint32_t compile_pic_;
- // Image sections
+ // Image section sizes/offsets correspond to the uncompressed form.
ImageSection sections_[kSectionCount];
// Image methods.