ARM: Use ubfx and movw instructions to avoid a PC-relative load on

src/platform-linux.cc

Index: src/platform-linux.cc
===================================================================
--- src/platform-linux.cc	(revision 10578)
+++ src/platform-linux.cc	(working copy)
@@ -596,12 +596,14 @@
 }
 
 
-VirtualMemory::VirtualMemory(size_t size, size_t alignment)
+VirtualMemory::VirtualMemory(size_t size, size_t alignment, intptr_t preferred)
     : address_(NULL), size_(0) {
   ASSERT(IsAligned(alignment, static_cast<intptr_t>(OS::AllocateAlignment())));
   size_t request_size = RoundUp(size + alignment,
                                 static_cast<intptr_t>(OS::AllocateAlignment()));
-  void* reservation = mmap(OS::GetRandomMmapAddr(),
+  void* reservation = mmap(preferred == 0 ?
+                               OS::GetRandomMmapAddr() :
+                               reinterpret_cast<void*>(preferred),
                            request_size,
                            PROT_NONE,
                            MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE,