ART: Compress LengthPrefixedArray on 32-bit targets.
Previously, the LengthPrefixedArray<ArtMethod> on 32-bit
targets contained a 64-bit length field followed by the
ArtMethod elements with size only a multiple of 4, not 8.
Consequently, an odd-length array broke the alignment for
the following array which would have the 64-bit length
placed at an unaligned address.
To fix that, we make the length field 32-bit and explicitly
pass the alignment information to the LengthPrefixedArray.
This also makes the 32-bit boot image a bit smaller.
On Nexus 5, AOSP, ToT, the field section is 11528B smaller
and the method section is 21036B smaller. 64-bit targets
should see the same savings for the field section but no
difference for the methods section.
Change-Id: I3e03e7b94129025c8a1c117c27645a34dec516d2
diff --git a/runtime/art_method.h b/runtime/art_method.h
index 85c03ed..8221fe2 100644
--- a/runtime/art_method.h
+++ b/runtime/art_method.h
@@ -513,6 +513,13 @@
(sizeof(PtrSizedFields) / sizeof(void*)) * pointer_size;
}
+ // Alignment of an instance of this object.
+ static size_t ObjectAlignment(size_t pointer_size) {
+ // The ArtMethod alignment is the same as image pointer size. This differs from
+ // alignof(ArtMethod) if cross-compiling with image_pointer_size_ != sizeof(void*).
+ return pointer_size;
+ }
+
void CopyFrom(const ArtMethod* src, size_t image_pointer_size)
SHARED_REQUIRES(Locks::mutator_lock_);