[ASan] Use less shadow on Win 32-bit

llvm-svn: 186393
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_win.cc b/compiler-rt/lib/sanitizer_common/sanitizer_win.cc
index 164dfdd..0a43aca 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_win.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_win.cc
@@ -40,6 +40,12 @@
   return 1U << 16;  // FIXME: is this configurable?
 }
 
+uptr GetMaxVirtualAddress() {
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+  return (uptr)si.lpMaximumApplicationAddress;
+}
+
 bool FileExists(const char *filename) {
   UNIMPLEMENTED();
 }