[UBSan] Call UBSan initialization as early as possible.

Specifically, use .preinit_array initialization on Linux and dynamic global
initializer on another platforms. Historically UBSan didn't have any
initialization code and its runtime was stateless. This is no longer the
case - UBSan relies on some non-trivial functionality from sanitizer_common
(e.g. online symbolization) and is now configurable by runtime flags.
Additionally, we've dropped support for enabling UBSan only for a few shared
objects, so UBSan is now always linked into the main executable, so now
we can use similar initialization as all the rest sanitizers.

llvm-svn: 213983

1 files changed, 24 insertions, 0 deletions

diff --git a/compiler-rt/lib/ubsan/ubsan_init.h b/compiler-rt/lib/ubsan/ubsan_init.h
new file mode 100644
index 00000000000..18356cfca61
--- /dev/null
+++ b/compiler-rt/lib/ubsan/ubsan_init.h
@@ -0,0 +1,24 @@
+//===-- ubsan_init.h --------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Initialization function for UBSan runtime.
+//
+//===----------------------------------------------------------------------===//
+#ifndef UBSAN_INIT_H
+#define UBSAN_INIT_H
+
+namespace __ubsan {
+
+// NOTE: This function might take a lock (if .preinit_array initialization is
+// not used). It's generally a bad idea to call it on a fast path.
+void InitIfNecessary();
+
+}  // namespace __ubsan
+
+#endif  // UBSAN_INIT_H