MMINLINE uintptr_t roundDownRegion(uintptr_t size) { return (size) & (~(_heapRegionManager->getRegionSize() - 1)); }
MMINLINE uintptr_t divideUpRegion(uintptr_t size) { /* TODO: use shift operation once region log2 size is introduced */ return (size + _heapRegionManager->getRegionSize() - 1) / _heapRegionManager->getRegionSize(); }
bool
MM_HeapVirtualMemory::initialize(MM_EnvironmentBase* env, uintptr_t size)
{
/* call the superclass to inialize before we do any work */
if (!MM_Heap::initialize(env)) {
return false;
}
MM_GCExtensionsBase* extensions = env->getExtensions();
uintptr_t padding = extensions->heapTailPadding;
uintptr_t effectiveHeapAlignment = _heapAlignment;
/* we need to ensure that we allocate the heap with region alignment since the region table requires that */
MM_HeapRegionManager* manager = getHeapRegionManager();
effectiveHeapAlignment = MM_Math::roundToCeiling(manager->getRegionSize(), effectiveHeapAlignment);
MM_MemoryManager* memoryManager = extensions->memoryManager;
bool created = false;
bool forcedOverflowProtection = false;
/* Under -Xaggressive ensure a full page of padding -- see JAZZ103 45254 */
if (extensions->padToPageSize) {
#if (defined(AIXPPC) && !defined(PPC64))
/*
* An attempt to allocate heap with top at 0xffffffff
* In this case extra padding is not required because of overflow protection padding can be used instead
*/
uintptr_t effectiveSize = MM_Math::roundToCeiling(manager->getRegionSize(), size);
void *preferredHeapBase = (void *)((uintptr_t)0 - effectiveSize);
created = memoryManager->createVirtualMemoryForHeap(env, &_vmemHandle, effectiveHeapAlignment, size, padding, preferredHeapBase, (void *)(extensions->heapCeiling));
if (created) {
/* overflow protection must be there to play role of padding even top is not so close to the end of the memory */
forcedOverflowProtection = true;
} else
#endif /* (defined(AIXPPC) && !defined(PPC64)) */
{
/* Ignore extra full page padding if page size is too large (hard coded here for 1G or larger) */
#define ONE_GB ((uintptr_t)1 * 1024 * 1024 * 1024)
if (extensions->requestedPageSize < ONE_GB)
{
if (padding < extensions->requestedPageSize) {
padding = extensions->requestedPageSize;
}
}
}
}
if (!created && !memoryManager->createVirtualMemoryForHeap(env, &_vmemHandle, effectiveHeapAlignment, size, padding, (void*)(extensions->preferredHeapBase), (void*)(extensions->heapCeiling))) {
return false;
}
/* Check we haven't overflowed the address range */
if (forcedOverflowProtection || (HIGH_ADDRESS - ((uintptr_t)memoryManager->getHeapTop(&_vmemHandle)) < (OVERFLOW_ROUNDING)) || extensions->fvtest_alwaysApplyOverflowRounding) {
/* Address range overflow */
memoryManager->roundDownTop(&_vmemHandle, OVERFLOW_ROUNDING);
}
extensions->overflowSafeAllocSize = ((HIGH_ADDRESS - (uintptr_t)(memoryManager->getHeapTop(&_vmemHandle))) + 1);
/* The memory returned might be less than we asked for -- get the actual size */
_maximumMemorySize = memoryManager->getMaximumSize(&_vmemHandle);
return true;
}