[PATCH, GCC, AArch64] Fix a couple of bugs in BTI

[Sudakshina Das]

Hi

While doing more testing I found a couple of issues with my BTI patches. 
This patch fixes them:
1) Remove a reference to return address key. The original patch was 
written based on a different not yet committed patch ([PATCH 
3/3][GCC][AARCH64] Add support for pointer authentication B key) and I 
missed out on cleaning this up. This is hidden behind the configuration 
option and thus went unnoticed.
2) Add a missed case for adding the BTI instruction in thunk functions.

Bootstrapped on aarch64-none-linux-gnu and regression tested on 
aarch64-none-elf with configuration turned on.

gcc/ChangeLog:

2019-xx-xx  Sudakshina Das  <sudi....@arm.com>

        * config/aarch64/aarch64.c (aarch64_output_mi_thunk): Add bti
        instruction if enabled.
        (aarch64_override_options): Remove reference to return address
        key.


Is this ok for trunk?
Sudi

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 9f52cc9..7d9824a 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -5980,6 +5980,9 @@ aarch64_output_mi_thunk (FILE *file, tree thunk ATTRIBUTE_UNUSED,
   rtx this_rtx, temp0, temp1, addr, funexp;
   rtx_insn *insn;
 
+  if (aarch64_bti_enabled ())
+    emit_insn (gen_bti_c());
+
   reload_completed = 1;
   emit_note (NOTE_INSN_PROLOGUE_END);
 
@@ -12032,7 +12035,6 @@ aarch64_override_options (void)
     {
 #ifdef TARGET_ENABLE_PAC_RET
       aarch64_ra_sign_scope = AARCH64_FUNCTION_NON_LEAF;
-      aarch64_ra_sign_key = AARCH64_KEY_A;
 #else
       aarch64_ra_sign_scope = AARCH64_FUNCTION_NONE;
 #endif