[PATCH v2 2/6] aarch64: define BTI_C and BTI_J macros as NOP unless HAVE_AARCH64_BTI

[Naohiro Tamura]

From: Naohiro Tamura <naohirot@jp.fujitsu.com>

This patch defines BTI_C and BTI_J macros conditionally for
performance.
If HAVE_AARCH64_BTI is true, BTI_C and BTI_J are defined as HINT
instruction for ARMv8.5 BTI (Branch Target Identification).
If HAVE_AARCH64_BTI is false, both BTI_C and BTI_J are defined as
NOP.
---
 sysdeps/aarch64/sysdep.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/sysdeps/aarch64/sysdep.h b/sysdeps/aarch64/sysdep.h
index 90acca4e42..b936e29cbd 100644
--- a/sysdeps/aarch64/sysdep.h
+++ b/sysdeps/aarch64/sysdep.h
@@ -62,8 +62,13 @@ strip_pac (void *p)
 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name
 
 /* Branch Target Identitication support.  */
-#define BTI_C		hint	34
-#define BTI_J		hint	36
+#if HAVE_AARCH64_BTI
+# define BTI_C		hint	34
+# define BTI_J		hint	36
+#else
+# define BTI_C		nop
+# define BTI_J		nop
+#endif
 
 /* Return address signing support (pac-ret).  */
 #define PACIASP		hint	25
-- 
2.17.1