[sanitizer] introduce MmapFixedOrDie and use it in SizeClassAllocator64

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@170099 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/sanitizer_common/sanitizer_win.cc b/lib/sanitizer_common/sanitizer_win.cc
index 49a4e8b..9f6f4f0 100644
--- a/lib/sanitizer_common/sanitizer_win.cc
+++ b/lib/sanitizer_common/sanitizer_win.cc
@@ -75,6 +75,8 @@
 }
 
 void *MmapFixedNoReserve(uptr fixed_addr, uptr size) {
+  // FIXME: is this really "NoReserve"? On Win32 this does not matter much,
+  // but on Win64 it does.
   void *p = VirtualAlloc((LPVOID)fixed_addr, size,
       MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
   if (p == 0)
@@ -83,6 +85,10 @@
   return p;
 }
 
+void *MmapFixedOrDie(uptr fixed_addr, uptr size) {
+  return MmapFixedOrDie(fixed_addr, size);
+}
+
 void *Mprotect(uptr fixed_addr, uptr size) {
   return VirtualAlloc((LPVOID)fixed_addr, size,
                       MEM_RESERVE | MEM_COMMIT, PAGE_NOACCESS);