Get rid of shadow maps for images
Fixed the image bitmap creation to use the End of the object section
instead of using the map size. This means that the bitmap covers at
most one word of bits past the end of the object section.
Reverts shadow map logic introduced by multi image CL:
(commit dcdc85bbd569f0ee66c331b4219c19304a616214)
Bug: 26317072
Change-Id: I181cf3490a5b292c00c6b0f97536f3206adcd091
diff --git a/runtime/gc/space/image_space.cc b/runtime/gc/space/image_space.cc
index dfdbd04..5f6bb8e 100644
--- a/runtime/gc/space/image_space.cc
+++ b/runtime/gc/space/image_space.cc
@@ -47,13 +47,15 @@
const char* image_location,
MemMap* mem_map,
accounting::ContinuousSpaceBitmap* live_bitmap,
- uint8_t* end,
- MemMap* shadow_map)
- : MemMapSpace(image_filename, mem_map, mem_map->Begin(), end, end,
+ uint8_t* end)
+ : MemMapSpace(image_filename,
+ mem_map,
+ mem_map->Begin(),
+ end,
+ end,
kGcRetentionPolicyNeverCollect),
oat_file_non_owned_(nullptr),
- image_location_(image_location),
- shadow_map_(shadow_map) {
+ image_location_(image_location) {
DCHECK(live_bitmap != nullptr);
live_bitmap_.reset(live_bitmap);
}
@@ -800,54 +802,19 @@
uint32_t bitmap_index = bitmap_index_.FetchAndAddSequentiallyConsistent(1);
std::string bitmap_name(StringPrintf("imagespace %s live-bitmap %u", image_filename,
bitmap_index));
+ // Bitmap only needs to cover until the end of the mirror objects section.
+ const ImageSection& image_objects = image_header.GetImageSection(ImageHeader::kSectionObjects);
std::unique_ptr<accounting::ContinuousSpaceBitmap> bitmap(
accounting::ContinuousSpaceBitmap::CreateFromMemMap(
bitmap_name,
image_bitmap_map.release(),
reinterpret_cast<uint8_t*>(map->Begin()),
- accounting::ContinuousSpaceBitmap::ComputeHeapSize(bitmap_section.Size())));
+ image_objects.End()));
if (bitmap == nullptr) {
*error_msg = StringPrintf("Could not create bitmap '%s'", bitmap_name.c_str());
return nullptr;
}
- // In case of multi-images, the images are spaced apart so that the bitmaps don't overlap. We
- // need to reserve the slack, as otherwise the large object space might allocate in there.
- // TODO: Reconsider the multi-image layout. b/26317072
- std::unique_ptr<MemMap> shadow_map;
- {
- uintptr_t image_begin = reinterpret_cast<uintptr_t>(image_header.GetImageBegin());
- uintptr_t image_end = RoundUp(image_begin + image_header.GetImageSize(), kPageSize);
- uintptr_t oat_begin = reinterpret_cast<uintptr_t>(image_header.GetOatFileBegin());
- if (image_end < oat_begin) {
- // There's a gap. Could be multi-image, could be the oat file spaced apart. Go ahead and
- // dummy-reserve the space covered by the bitmap (which will be a shadow that introduces
- // a gap to the next image).
- uintptr_t heap_size = bitmap->HeapSize();
- uintptr_t bitmap_coverage_end = RoundUp(image_begin + heap_size, kPageSize);
- if (bitmap_coverage_end > image_end) {
- VLOG(startup) << "Reserving bitmap shadow ["
- << std::hex << image_end << ";"
- << std::hex << bitmap_coverage_end << ";] (oat file begins at "
- << std::hex << oat_begin;
- // Note: we cannot use MemMap::Dummy here, as that won't reserve the space in 32-bit mode.
- shadow_map.reset(MemMap::MapAnonymous("Image bitmap shadow",
- reinterpret_cast<uint8_t*>(image_end),
- bitmap_coverage_end - image_end,
- PROT_NONE,
- false,
- false,
- error_msg));
- if (shadow_map == nullptr) {
- return nullptr;
- }
- // madvise it away, we don't really want it, just reserve the address space.
- // TODO: Should we use MadviseDontNeedAndZero? b/26317072
- madvise(shadow_map->BaseBegin(), shadow_map->BaseSize(), MADV_DONTNEED);
- }
- }
- }
-
// We only want the mirror object, not the ArtFields and ArtMethods.
uint8_t* const image_end =
map->Begin() + image_header.GetImageSection(ImageHeader::kSectionObjects).End();
@@ -855,8 +822,7 @@
image_location,
map.release(),
bitmap.release(),
- image_end,
- shadow_map.release()));
+ image_end));
// VerifyImageAllocations() will be called later in Runtime::Init()
// as some class roots like ArtMethod::java_lang_reflect_ArtMethod_
diff --git a/runtime/gc/space/image_space.h b/runtime/gc/space/image_space.h
index b8ae4a0..9c8e8b2 100644
--- a/runtime/gc/space/image_space.h
+++ b/runtime/gc/space/image_space.h
@@ -171,8 +171,7 @@
const char* image_location,
MemMap* mem_map,
accounting::ContinuousSpaceBitmap* live_bitmap,
- uint8_t* end,
- MemMap* shadow_map = nullptr);
+ uint8_t* end);
// The OatFile associated with the image during early startup to
// reserve space contiguous to the image. It is later released to
@@ -185,10 +184,6 @@
const std::string image_location_;
- // A MemMap reserving the space of the bitmap "shadow," so that we don't allocate into it. Only
- // used in the multi-image case.
- std::unique_ptr<MemMap> shadow_map_;
-
private:
DISALLOW_COPY_AND_ASSIGN(ImageSpace);
};
