[PATCH 3/3] switchcontext.S: Include and use _CET_ENDBR

[H.J. Lu via Gcc-patches]

When __CET__ is defined, <cet.h> should be included to add Intel CET
marker to object file and _CET_ENDBR should be placed at function entry
to indicate indirect branch target.

        * libdruntime/config/x86/switchcontext.S: Include <cet.h> if
        __CET__ is defined.
        (_CET_ENDBR): New.  Define if __CET__ is not defined.
        (fiber_switchContext): Add _CET_ENDBR after .cfi_startproc.
---
 libphobos/libdruntime/config/x86/switchcontext.S | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libphobos/libdruntime/config/x86/switchcontext.S 
b/libphobos/libdruntime/config/x86/switchcontext.S
index f5d1a87eb01..35063af491c 100644
--- a/libphobos/libdruntime/config/x86/switchcontext.S
+++ b/libphobos/libdruntime/config/x86/switchcontext.S
@@ -24,6 +24,12 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If 
not, see
 
 #include "../common/threadasm.S"
 
+#ifdef __CET__
+# include <cet.h>
+#else
+# define _CET_ENDBR
+#endif
+
 #if defined(__i386__)
 
     .text
@@ -32,6 +38,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If 
not, see
     .align 16
 CSYM(fiber_switchContext):
     .cfi_startproc
+    _CET_ENDBR
     // save current stack state
     push %ebp
     mov  %esp, %ebp
@@ -66,6 +73,7 @@ CSYM(fiber_switchContext):
     .align 16
 CSYM(fiber_switchContext):
     .cfi_startproc
+    _CET_ENDBR
     // Save current stack state.save current stack state
     push %rbp
     mov  %rsp, %rbp
-- 
2.26.2