commit 479b1de64cd7a8c9c8ca182c699cb2048850c35d
author Andreas Gampe <agampe@google.com> Tue Jul 19 18:27:17 2016 -0700
committer Andreas Gampe <agampe@google.com> Thu Jul 21 15:47:35 2016 -0700
tree bca0b26c4e210e56d25baca49f7a25ffe9178813
parent 75f0885d7c3d72a0351912b6d47682e1c860efdf

ART: Remove PACKED from ArtMethod's ptr_sized_fields_

Remove the PACKED(4) hack, as it's highly annoying when debugging
a 64-bit process. Instead, fix the actual offset and size computation
for cross-size accesses.

Test: m test-art-host
Change-Id: I295c78760b74b6a62946e76856f218b4eb159cdc

runtime/art_method.cc

diff --git a/runtime/art_method.cc b/runtime/art_method.cc
index c4d961f..113827a 100644
--- a/runtime/art_method.cc
+++ b/runtime/art_method.cc
@@ -16,6 +16,8 @@
 
 #include "art_method.h"
 
+#include <cstddef>
+
 #include "arch/context.h"
 #include "art_field-inl.h"
 #include "art_method-inl.h"
@@ -498,6 +500,18 @@
 }
 
 bool ArtMethod::IsImagePointerSize(size_t pointer_size) {
+  // Hijack this function to get access to PtrSizedFieldsOffset.
+  //
+  // Ensure that PrtSizedFieldsOffset is correct. We rely here on usually having both 32-bit and
+  // 64-bit builds.
+  static_assert(std::is_standard_layout<ArtMethod>::value, "ArtMethod is not standard layout.");
+  static_assert((sizeof(void*) != 4) ||
+                    (offsetof(ArtMethod, ptr_sized_fields_) == PtrSizedFieldsOffset(4)),
+                "Unexpected 32-bit class layout.");
+  static_assert((sizeof(void*) != 8) ||
+                    (offsetof(ArtMethod, ptr_sized_fields_) == PtrSizedFieldsOffset(8)),
+                "Unexpected 64-bit class layout.");
+
   Runtime* runtime = Runtime::Current();
   if (runtime == nullptr) {
     return true;

runtime/art_method.h

diff --git a/runtime/art_method.h b/runtime/art_method.h
index 91a4424..d75113e 100644
--- a/runtime/art_method.h
+++ b/runtime/art_method.h
@@ -17,6 +17,8 @@
 #ifndef ART_RUNTIME_ART_METHOD_H_
 #define ART_RUNTIME_ART_METHOD_H_
 
+#include <cstddef>
+
 #include "base/bit_utils.h"
 #include "base/casts.h"
 #include "dex_file.h"
@@ -219,7 +221,7 @@
 class ArtMethod FINAL {
  public:
   ArtMethod() : access_flags_(0), dex_code_item_offset_(0), dex_method_index_(0),
-      method_index_(0) { }
+      method_index_(0), hotness_count_(0) { }
 
   ArtMethod(ArtMethod* src, size_t image_pointer_size) {
     CopyFrom(src, image_pointer_size);
@@ -657,7 +659,7 @@
 
   // Size of an instance of this native class.
   static size_t Size(size_t pointer_size) {
-    return RoundUp(OFFSETOF_MEMBER(ArtMethod, ptr_sized_fields_), pointer_size) +
+    return PtrSizedFieldsOffset(pointer_size) +
         (sizeof(PtrSizedFields) / sizeof(void*)) * pointer_size;
   }
 
@@ -744,9 +746,7 @@
   // Fake padding field gets inserted here.
 
   // Must be the last fields in the method.
-  // PACKED(4) is necessary for the correctness of
-  // RoundUp(OFFSETOF_MEMBER(ArtMethod, ptr_sized_fields_), pointer_size).
-  struct PACKED(4) PtrSizedFields {
+  struct PtrSizedFields {
     // Short cuts to declaring_class_->dex_cache_ member for fast compiled code access.
     ArtMethod** dex_cache_resolved_methods_;
 
@@ -763,9 +763,9 @@
   } ptr_sized_fields_;
 
  private:
-  static size_t PtrSizedFieldsOffset(size_t pointer_size) {
-    // Round up to pointer size for padding field.
-    return RoundUp(OFFSETOF_MEMBER(ArtMethod, ptr_sized_fields_), pointer_size);
+  static constexpr size_t PtrSizedFieldsOffset(size_t pointer_size) {
+    // Round up to pointer size for padding field. Tested in art_method.cc.
+    return RoundUp(offsetof(ArtMethod, hotness_count_) + sizeof(hotness_count_), pointer_size);
   }
 
   // Compare given pointer size to the image pointer size.