[K/N] Fix ExtraObjectCell::size on 32-bit targets ^KT-78925

    Allocate multiples of `sizeof(Cell)` bytes, even if `sizeof(ExtraObjectCell)` is less than this.

Author: haitaka

kotlin-native/runtime/src/alloc/custom/cpp/CustomAllocatorTestSupport.cpp

@@ -26,7 +26,7 @@ kotlin::alloc::test_support::WithSchedulerNotificationHook::~WithSchedulerNotifi
 }
 
 kotlin::alloc::ExtraObjectCell* kotlin::alloc::test_support::initExtraObjectCell(uint8_t* ptr) {
-    EXPECT_TRUE(ptr[0] == 0 && memcmp(ptr, ptr + 1, kExtraObjCellSize.inBytes() - 1) == 0);
+    EXPECT_TRUE(ptr[0] == 0 && memcmp(ptr, ptr + 1, ExtraObjectCell::size().inBytes() - 1) == 0);
     auto* extraObjCell = new(ptr) ExtraObjectCell();
     new(extraObjCell->data_) kotlin::mm::ExtraObjectData(nullptr, nullptr);
     return extraObjCell;

kotlin-native/runtime/src/alloc/custom/cpp/CustomAllocatorTestSupport.hpp

@@ -83,8 +83,6 @@ class WithSchedulerNotificationHook {
     testing::StrictMock<testing::MockFunction<void(std::size_t)>> schedulerNotificationHook_;
 };
 
-constexpr auto kExtraObjCellSize = AllocationSize::bytesExactly(sizeof(kotlin::alloc::ExtraObjectCell));
-
 ExtraObjectCell* initExtraObjectCell(uint8_t* ptr);
 ExtraObjectCell* allocExtraObjectCell(kotlin::alloc::FixedBlockPage* page);
 ExtraObjectCell* allocExtraObjectCell(kotlin::alloc::SingleObjectPage* page);

kotlin-native/runtime/src/alloc/custom/cpp/ExtraObjectCell.hpp

@@ -11,7 +11,7 @@ namespace kotlin::alloc {
 
 struct ExtraObjectCell {
     static constexpr AllocationSize size() {
-        return AllocationSize::bytesExactly(sizeof(ExtraObjectCell));
+        return AllocationSize::bytesAtLeast(sizeof(ExtraObjectCell));
     }
 
     static ExtraObjectCell* fromExtraObject(mm::ExtraObjectData* extraObjectData) {
@@ -27,4 +27,7 @@ struct ExtraObjectCell {
     };
 };
 
-} // namespace kotlin::alloc
+// ensure const-evaluatable
+static_assert(ExtraObjectCell::size().inCells() > 0);
+
+} // namespace kotlin::alloc

kotlin-native/runtime/src/alloc/custom/cpp/GCApi.cpp

@@ -103,7 +103,7 @@ bool kotlin::alloc::ExtraDataSweepTraits::trySweepElement(uint8_t* element, Fina
 }
 
 kotlin::alloc::AllocationSize kotlin::alloc::ExtraDataSweepTraits::elementSize(uint8_t*) {
-    return AllocationSize::bytesExactly(sizeof(ExtraObjectCell));
+    return ExtraObjectCell::size();
 }
 
 void* kotlin::alloc::SafeAlloc(uint64_t size) noexcept {

kotlin-native/runtime/src/alloc/custom/cpp/NextFitPage.hpp

@@ -104,6 +104,9 @@ class alignas(kPageAlignment) NextFitPage : public MultiObjectPage<NextFitPage>
     Cell cells_[]; // cells_[0] is reserved for an empty block
 };
 
+// ensure const-evaluatable
+static_assert(NextFitPage::cellCount() > 0);
+
 } // namespace kotlin::alloc
 
 #endif

kotlin-native/runtime/src/alloc/custom/cpp/SweepTest.cpp

@@ -27,7 +27,7 @@ using ExtraObjectCell = typename kotlin::alloc::ExtraObjectCell;
 } // namespace
 
 TEST_F(CustomAllocatorTest, ExtraDataSweepFullFinalizedPage) {
-    auto* page = FixedBlockPage::Create(kExtraObjCellSize.inCells());
+    auto* page = FixedBlockPage::Create(ExtraObjectCell::size().inCells());
     while (ExtraObjectCell* cell = allocExtraObjectCell(page)) {
         cell->Data()->setFlag(kotlin::mm::ExtraObjectData::FLAGS_SWEEPABLE);
     }