on windows use 4TiB area for aligned allocation
@@ -184,6 +184,18 @@ static bool mi_os_mem_free(void* addr, size_t size, mi_stats_t* stats)
#ifdef _WIN32
static void* mi_win_virtual_allocx(void* addr, size_t size, size_t try_alignment, DWORD flags) {
+#if (MI_INTPTR_SIZE >= 8)
+ // on 64-bit systems, use the virtual address area after 4TiB for 4MiB aligned allocations
+ static volatile intptr_t aligned_base = ((intptr_t)4 << 40); // starting at 4TiB
+ if (addr == NULL && try_alignment > 0 &&
+ try_alignment <= MI_SEGMENT_SIZE && (size%MI_SEGMENT_SIZE) == 0)
+ {
+ intptr_t hint = mi_atomic_add(&aligned_base, size) - size;
+ if (hint%try_alignment == 0) {
+ return VirtualAlloc((void*)hint, size, flags, PAGE_READWRITE);
+ }
+ }
+#endif
#if defined(MEM_EXTENDED_PARAMETER_TYPE_BITS)
if (try_alignment > 0 && (try_alignment % _mi_os_page_size()) == 0 && pVirtualAlloc2 != NULL) {
// on modern Windows try use VirtualAlloc2 for aligned allocation
