[PATCH] arm: Fix missing bti instruction for virtual thunks

[Richard Ball]

Adds missing bti instruction at the beginning of a virtual
thunk, when bti is enabled.

gcc/ChangeLog:

        * config/arm/arm.cc (arm_output_mi_thunk): Emit
        insn for bti_c when bti is enabled.

gcc/testsuite/ChangeLog:

        * g++.target/arm/bti_thunk.C: New test.
diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
index e5a944486d7bd583627b0e22dfe8f95862e975bb..91eee8be7c1a59118fbf443557561fb3e0689d61 100644
--- a/gcc/config/arm/arm.cc
+++ b/gcc/config/arm/arm.cc
@@ -29257,6 +29257,8 @@ arm_output_mi_thunk (FILE *file, tree thunk, HOST_WIDE_INT delta,
   const char *fnname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (thunk));
 
   assemble_start_function (thunk, fnname);
+  if (aarch_bti_enabled ())
+    emit_insn (aarch_gen_bti_c());
   if (TARGET_32BIT)
     arm32_output_mi_thunk (file, thunk, delta, vcall_offset, function);
   else
diff --git a/gcc/testsuite/g++.target/arm/bti_thunk.C b/gcc/testsuite/g++.target/arm/bti_thunk.C
new file mode 100644
index 0000000000000000000000000000000000000000..5c4a8e5a8d74581eca2b877c000a5b34ddca0e9b
--- /dev/null
+++ b/gcc/testsuite/g++.target/arm/bti_thunk.C
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-march=armv8.1-m.main+pacbti -O1 -mbranch-protection=bti --save-temps" } */
+
+#include <stdio.h>
+
+struct C18 {
+  virtual void f7();
+};
+
+struct C19 : virtual C18 {
+  virtual void f7();
+};
+
+void C19::f7() {
+  printf("foo\n");
+}
+
+/* { dg-final { scan-assembler-times "\tbti" 2 } } */
\ No newline at end of file