[PATCH 2/3][GCC][AARCH64] Add new -mbranch-protection option to combine pointer signing and BTI

gcc/ChangeLog:

2019-01-08  Sam Tebbs  <sam.tebbs@arm.com>

	* config/aarch64/aarch64.c (BRANCH_PROTECT_STR_MAX,
	aarch64_parse_branch_protection,
	struct aarch64_branch_protect_type,
	aarch64_handle_no_branch_protection,
	aarch64_handle_standard_branch_protection,
	aarch64_validate_mbranch_protection,
	aarch64_handle_pac_ret_protection,
	aarch64_handle_attr_branch_protection,
	accepted_branch_protection_string,
	aarch64_pac_ret_subtypes,
	aarch64_branch_protect_types,
	aarch64_handle_pac_ret_leaf): Define.
	(aarch64_override_options_after_change_1, aarch64_override_options):
	Add check for accepted_branch_protection_string.
	(aarch64_option_save): Save accepted_branch_protection_string.
	(aarch64_option_restore): Save accepted_branch_protection_string.
	* config/aarch64/aarch64.c (aarch64_attributes): Add branch-protection.
	* config/aarch64/aarch64.opt: Add mbranch-protection. Deprecate
	msign-return-address.
	* doc/invoke.texi: Add mbranch-protection.

gcc/testsuite/Changelog:

2019-01-08  Sam Tebbs  <sam.tebbs@arm.com>

	* gcc.target/aarch64/(return_address_sign_1.c,
	return_address_sign_2.c, return_address_sign_3.c (__attribute__)):
	Change option to -mbranch-protection.
	* gcc.target/aarch64/(branch-protection-option.c,
	branch-protection-option-2.c, branch-protection-attr.c,
	branch-protection-attr-2.c): New file.

From-SVN: r267717

gcc/ChangeLog

+2019-01-08  Sam Tebbs  <sam.tebbs@arm.com>
+
+	* config/aarch64/aarch64.c (BRANCH_PROTECT_STR_MAX,
+	aarch64_parse_branch_protection,
+	struct aarch64_branch_protect_type,
+	aarch64_handle_no_branch_protection,
+	aarch64_handle_standard_branch_protection,
+	aarch64_validate_mbranch_protection,
+	aarch64_handle_pac_ret_protection,
+	aarch64_handle_attr_branch_protection,
+	accepted_branch_protection_string,
+	aarch64_pac_ret_subtypes,
+	aarch64_branch_protect_types,
+	aarch64_handle_pac_ret_leaf): Define.
+	(aarch64_override_options_after_change_1, aarch64_override_options):
+	Add check for accepted_branch_protection_string.
+	(aarch64_option_save): Save accepted_branch_protection_string.
+	(aarch64_option_restore): Save accepted_branch_protection_string.
+	* config/aarch64/aarch64.c (aarch64_attributes): Add branch-protection.
+	* config/aarch64/aarch64.opt: Add mbranch-protection. Deprecate
+	msign-return-address.
+	* doc/invoke.texi: Add mbranch-protection.
+
 2019-01-08  Alan Modra  <amodra@gmail.com>
 
 	PR target/88614

gcc/config/aarch64/aarch64.opt

@@ -149,8 +149,12 @@ mpc-relative-literal-loads
 Target Report Save Var(pcrelative_literal_loads) Init(2) Save
 PC relative literal loads.
 
+mbranch-protection=
+Target RejectNegative Joined Var(aarch64_branch_protection_string) Save
+Use branch-protection features.
+
 msign-return-address=
-Target RejectNegative Report Joined Enum(aarch64_ra_sign_scope_t) Var(aarch64_ra_sign_scope) Init(AARCH64_FUNCTION_NONE) Save
+Target Deprecated RejectNegative Joined Enum(aarch64_ra_sign_scope_t) Var(aarch64_ra_sign_scope) Init(AARCH64_FUNCTION_NONE) Save
 Select return address signing scope.
 
 Enum

gcc/doc/invoke.texi

@@ -631,6 +631,7 @@ Objective-C and Objective-C++ Dialects}.
 -mlow-precision-recip-sqrt  -mlow-precision-sqrt  -mlow-precision-div @gol
 -mpc-relative-literal-loads @gol
 -msign-return-address=@var{scope} @gol
+-mbranch-protection=@var{none}|@var{standard}|@var{pac-ret}[+@var{leaf}] @gol
 -march=@var{name}  -mcpu=@var{name}  -mtune=@var{name}  @gol
 -moverride=@var{string}  -mverbose-cost-dump  -mtrack-speculation} 
 
@@ -15738,7 +15739,21 @@ Select the function scope on which return address signing will be applied.
 Permissible values are @samp{none}, which disables return address signing,
 @samp{non-leaf}, which enables pointer signing for functions which are not leaf
 functions, and @samp{all}, which enables pointer signing for all functions.  The
-default value is @samp{none}.
+default value is @samp{none}. This option has been deprecated by
+-mbranch-protection.
+
+@item -mbranch-protection=@var{none}|@var{standard}|@var{pac-ret}[+@var{leaf}]
+@opindex mbranch-protection
+Select the branch protection features to use.
+@samp{none} is the default and turns off all types of branch protection.
+@samp{standard} turns on all types of branch protection features.  If a feature
+has additional tuning options, then @samp{standard} sets it to its standard
+level.
+@samp{pac-ret[+@var{leaf}]} turns on return address signing to its standard
+level: signing functions that save the return address to memory (non-leaf
+functions will practically always do this) using the a-key.  The optional
+argument @samp{leaf} can be used to extend the signing to include leaf
+functions.
 
 @item -msve-vector-bits=@var{bits}
 @opindex msve-vector-bits

gcc/testsuite/ChangeLog

+2019-01-08  Sam Tebbs  <sam.tebbs@arm.com>
+
+	* gcc.target/aarch64/(return_address_sign_1.c,
+	return_address_sign_2.c, return_address_sign_3.c (__attribute__)):
+	Change option to -mbranch-protection.
+	* gcc.target/aarch64/(branch-protection-option.c,
+	branch-protection-option-2.c, branch-protection-attr.c,
+	branch-protection-attr-2.c): New file.
+
 2019-01-08  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* g++.dg/diagnostic/out-of-class-redeclaration.C: New.

gcc/testsuite/gcc.target/aarch64/branch-protection-attr-2.c

+/* { dg-do "compile" } */
+
+void __attribute__ ((target("branch-protection=pac-ret+leaf,branch-protection=none")))
+foo ()
+{
+}
+
+void __attribute__ ((target("branch-protection=pac-ret,branch-protection=none")))
+foo2 ()
+{
+  /* Function call here to make this a non-leaf function, so that it is covered by pac-ret.  */
+  foo ();
+}
+
+/* { dg-final { scan-assembler-not "\tautiasp\t" } } */
+/* { dg-final { scan-assembler-not "\tpaciasp\t" } } */

gcc/testsuite/gcc.target/aarch64/branch-protection-attr.c

+/* { dg-do "compile" } */
+
+void __attribute__ ((target("branch-protection=leaf")))
+foo1 ()
+{
+}
+/* { dg-error {invalid protection type \("leaf"\) in 'target\("branch-protection="\)' pragma or attribute} "" { target *-*-* } 5 } */
+/* { dg-error {pragma or attribute 'target\("branch-protection=leaf"\)' is not valid} "" { target *-*-* } 5 } */
+
+void __attribute__ ((target("branch-protection=none+pac-ret")))
+foo2 ()
+{
+}
+/* { dg-error "unexpected 'pac-ret' after 'none'" "" { target *-*-* } 12 } */
+/* { dg-error {pragma or attribute 'target\("branch-protection=none\+pac-ret"\)' is not valid} "" { target *-*-* } 12 } */
+
+void __attribute__ ((target("branch-protection=")))
+foo3 ()
+{
+}
+/* { dg-error {missing argument to 'target\("branch-protection="\)' pragma or attribute} "" { target *-*-* } 19 } */
+/* { dg-error {pragma or attribute 'target\("branch-protection="\)' is not valid} "" { target *-*-* } 19 } */

gcc/testsuite/gcc.target/aarch64/branch-protection-option-2.c

+/* { dg-do "compile" } */
+/* { dg-options "-mbranch-protection=pac-ret+leaf -mbranch-protection=none" } */
+
+void foo2 ()
+{
+}
+
+/* { dg-final { scan-assembler-not "\tautiasp\t" } } */
+/* { dg-final { scan-assembler-not "\tpaciasp\t" } } */

gcc/testsuite/gcc.target/aarch64/branch-protection-option.c

+/* { dg-do "compile" } */
+/* { dg-options "-mbranch-protection=leaf -mbranch-protection=none+pac-ret" } */
+
+/* { dg-error "unexpected 'pac-ret' after 'none'"  "" { target *-*-* } 0 } */

gcc/testsuite/gcc.target/aarch64/return_address_sign_1.c

 /* Testing return address signing where no combined instructions used.  */
 /* { dg-do compile } */
-/* { dg-options "-O2 -msign-return-address=all" } */
+/* { dg-options "-O2 -mbranch-protection=pac-ret+leaf" } */
 /* { dg-require-effective-target lp64 } */
 
 int foo (int);

gcc/testsuite/gcc.target/aarch64/return_address_sign_2.c

 /* Testing return address signing where combined instructions used.  */
 /* { dg-do compile } */
-/* { dg-options "-O2 -msign-return-address=all" } */
+/* { dg-options "-O2 -mbranch-protection=pac-ret+leaf" } */
 /* { dg-require-effective-target lp64 } */
 
 int foo (int);

gcc/testsuite/gcc.target/aarch64/return_address_sign_3.c

 /* Testing the disable of return address signing.  */
 /* { dg-do compile } */
-/* { dg-options "-O2 -msign-return-address=all" } */
+/* { dg-options "-O2 -mbranch-protection=pac-ret+leaf" } */
 /* { dg-require-effective-target lp64 } */
 
 int bar (int, int);
 
-int __attribute__ ((target ("arch=armv8.3-a, sign-return-address=non-leaf")))
+int __attribute__ ((target ("arch=armv8.3-a, branch-protection=pac-ret")))
 func1_leaf (int a, int b, int c, int d)
 {
   return a + b + c + d;
 }
 
-int __attribute__ ((target ("arch=armv8.3-a, sign-return-address=none")))
+int __attribute__ ((target ("arch=armv8.3-a, branch-protection=none")))
 func2_none (int a, int b, int c, int d)
 {
   return c + bar (a, b) + d;