Add forgotten file.

From-SVN: r205701

libsanitizer/sanitizer_common/sanitizer_asm.h

+//===-- sanitizer_asm.h -----------------------------------------*- C++ -*-===//
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Various support for assemebler.
+//
+//===----------------------------------------------------------------------===//
+
+// Some toolchains do not support .cfi asm directives, so we have to hide
+// them inside macros.
+#if defined(__clang__) ||                                                      \
+    (defined(__GNUC__) && defined(__GCC_HAVE_DWARF2_CFI_ASM))
+  // GCC defined __GCC_HAVE_DWARF2_CFI_ASM if it supports CFI.
+  // Clang seems to support CFI by default (or not?).
+  // We need two versions of macros: for inline asm and standalone asm files.
+# define CFI_INL_ADJUST_CFA_OFFSET(n) ".cfi_adjust_cfa_offset " #n ";"
+
+# define CFI_STARTPROC .cfi_startproc
+# define CFI_ENDPROC .cfi_endproc
+# define CFI_ADJUST_CFA_OFFSET(n) .cfi_adjust_cfa_offset n
+# define CFI_REL_OFFSET(reg, n) .cfi_rel_offset reg, n
+# define CFI_DEF_CFA_REGISTER(reg) .cfi_def_cfa_register reg
+# define CFI_RESTORE(reg) .cfi_restore reg
+
+#else  // No CFI
+# define CFI_INL_ADJUST_CFA_OFFSET(n)
+# define CFI_STARTPROC
+# define CFI_ENDPROC
+# define CFI_ADJUST_CFA_OFFSET(n)
+# define CFI_REL_OFFSET(reg, n)
+# define CFI_DEF_CFA_REGISTER(reg)
+# define CFI_RESTORE(reg)
+#endif