raw_addr &= V8_UINT64_C(0x3ffffffff000);
#else
uint32_t raw_addr = V8::RandomPrivate(isolate);
+
+ raw_addr &= 0x3ffff000;
+
+# ifdef __sun
+ // For our Solaris/illumos mmap hint, we pick a random address in the bottom
+ // half of the top half of the address space (that is, the third quarter).
+ // Because we do not MAP_FIXED, this will be treated only as a hint -- the
+ // system will not fail to mmap() because something else happens to already
+ // be mapped at our random address. We deliberately set the hint high enough
+ // to get well above the system's break (that is, the heap); Solaris and
+ // illumos will try the hint and if that fails allocate as if there were
+ // no hint at all. The high hint prevents the break from getting hemmed in
+ // at low values, ceding half of the address space to the system heap.
+ raw_addr += 0x80000000;
+# else
// The range 0x20000000 - 0x60000000 is relatively unpopulated across a
// variety of ASLR modes (PAE kernel, NX compat mode, etc) and on macos
// 10.6 and 10.7.
- raw_addr &= 0x3ffff000;
raw_addr += 0x20000000;
+# endif
#endif
return reinterpret_cast<void*>(raw_addr);
}