[PATCH][GCC][AARCH64] Add effective-target check to b key execution tests

gcc/testsuite
2019-08-09  Sam Tebbs<sam.tebbs@arm.com>

	* lib/target-supports.exp
	(check_effective_target_arm_v8_4a_bkey_directive): New proc.
	* g++.target/aarch64/return_address_sign_b_exception.C,
	return_address_sign_ab_exception.C: Add dg-require-effective-target
	checks.

From-SVN: r274236

gcc/testsuite/ChangeLog

+2019-08-09  Sam Tebbs <sam.tebbs@arm.com>
+
+	* lib/target-supports.exp
+	(check_effective_target_arm_v8_4a_bkey_directive): New proc.
+	* g++.target/aarch64/return_address_sign_b_exception.C,
+	return_address_sign_ab_exception.C: Add dg-require-effective-target
+	checks.
+
 2019-08-09  Richard Sandiford  <richard.sandiford@arm.com>
 
 	PR middle-end/90313

gcc/testsuite/g++.target/aarch64/return_address_sign_ab_exception.C

 /* { dg-do run } */
 /* { dg-options "--save-temps" } */
+/* { dg-require-effective-target arm_v8_3a_bkey_directive } */
 
 __attribute__((target("branch-protection=pac-ret+leaf")))
 int foo_a () {

gcc/testsuite/g++.target/aarch64/return_address_sign_b_exception.C

 /* { dg-do run } */
 /* { dg-options "-mbranch-protection=pac-ret+leaf+b-key --save-temps" } */
+/* { dg-require-effective-target arm_v8_3a_bkey_directive } */
 
 int foo () {
   throw 22;

gcc/testsuite/lib/target-supports.exp

@@ -9463,6 +9463,16 @@ proc check_effective_target_arm_v8_3a_complex_neon_hw { } {
     } [add_options_for_arm_v8_3a_complex_neon ""]]
 }
 
+# Return 1 if the assembler supports assembling the Armv8.3 pointer authentication B key directive
+proc check_effective_target_arm_v8_3a_bkey_directive { } {
+	return [check_no_compiler_messages cet object {
+		int main(void) {
+			asm (".cfi_b_key_frame");
+			return 0;
+		}
+	}]
+}
+
 # Returns 1 if the target is using glibc, 0 otherwise.
 
 proc check_effective_target_glibc { } {