[PATCH 5/15] arm: Implement target feature macros for PACBTI

This patch implements target feature macros when PACBTI is enabled
through the -march option or -mbranch-protection.  The target feature
macros __ARM_FEATURE_PAC_DEFAULT and __ARM_FEATURE_BTI_DEFAULT are
specified in ARM ACLE
<https://developer.arm.com/documentation/101028/0012/5--Feature-test-macros?lang=en>
__ARM_FEATURE_PAUTH and __ARM_FEATURE_BTI are specified in the
pull-request <https://github.com/ARM-software/acle/pull/55>.

Approved here
<https://gcc.gnu.org/pipermail/gcc-patches/2021-December/586334.html>.

gcc/

	* config/arm/arm-c.cc (arm_cpu_builtins): Define
	__ARM_FEATURE_BTI_DEFAULT, __ARM_FEATURE_PAC_DEFAULT,
	__ARM_FEATURE_PAUTH and __ARM_FEATURE_BTI.

gcc/testsuite/

	* lib/target-supports.exp
	(check_effective_target_mbranch_protection_ok): New function.
	* gcc.target/arm/acle/pacbti-m-predef-2.c: New test.
	* gcc.target/arm/acle/pacbti-m-predef-4.c: Likewise.
	* gcc.target/arm/acle/pacbti-m-predef-5.c: Likewise.
	* gcc.target/arm/acle/pacbti-m-predef-8.c: Likewise.
	* gcc.target/arm/acle/pacbti-m-predef-9.c: Likewise.
	* gcc.target/arm/acle/pacbti-m-predef-10.c: Likewise.
	* gcc.target/arm/acle/pacbti-m-predef-11.c: Likewise.
	* gcc.target/arm/acle/pacbti-m-predef-12.c: Likewise.

Co-Authored-By: Tejas Belagod  <tbelagod@arm.com>

10 files changed, 153 insertions, 0 deletions

diff --git a/gcc/config/arm/arm-c.cc b/gcc/config/arm/arm-c.cc
index df86342..59c0d8c 100644
--- a/gcc/config/arm/arm-c.cc
+++ b/gcc/config/arm/arm-c.cc
@@ -214,6 +214,24 @@ arm_cpu_builtins (struct cpp_reader* pfile)
   def_or_undef_macro (pfile, "__ARM_FEATURE_COMPLEX", TARGET_COMPLEX);
   def_or_undef_macro (pfile, "__ARM_32BIT_STATE", TARGET_32BIT);
 
+  def_or_undef_macro (pfile, "__ARM_FEATURE_PAUTH", TARGET_HAVE_PACBTI);
+  def_or_undef_macro (pfile, "__ARM_FEATURE_BTI", TARGET_HAVE_PACBTI);
+  def_or_undef_macro (pfile, "__ARM_FEATURE_BTI_DEFAULT",
+		      aarch_enable_bti == 1);
+
+  cpp_undef (pfile, "__ARM_FEATURE_PAC_DEFAULT");
+  if (aarch_ra_sign_scope != AARCH_FUNCTION_NONE)
+  {
+    unsigned int pac = 1;
+
+    gcc_assert (aarch_ra_sign_key == AARCH_KEY_A);
+
+    if (aarch_ra_sign_scope == AARCH_FUNCTION_ALL)
+      pac |= 0x4;
+
+    builtin_define_with_int_value ("__ARM_FEATURE_PAC_DEFAULT", pac);
+  }
+
   cpp_undef (pfile, "__ARM_FEATURE_MVE");
   if (TARGET_HAVE_MVE && TARGET_HAVE_MVE_FLOAT)
     {
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-10.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-10.c
new file mode 100644
index 0000000..52d1823
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-10.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target mbranch_protection_ok } */
+/* { dg-additional-options "-march=armv8.1-m.main+fp -mbranch-protection=bti+pac-ret -mfloat-abi=hard" } */
+
+#if (__ARM_FEATURE_BTI_DEFAULT != 1)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be defined to 1."
+#endif
+
+#if !defined (__ARM_FEATURE_PAC_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be defined."
+#endif
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-11.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-11.c
new file mode 100644
index 0000000..9f27110
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-11.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-skip-if "avoid conflicting multilib options" { *-*-* } { "-marm" "-mcpu=*" "-mfloat-abi=*" } } */
+/* { dg-options "-march=armv8.1-m.main+pacbti" } */
+
+#if (__ARM_FEATURE_BTI != 1)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be defined to 1."
+#endif
+
+#if (__ARM_FEATURE_PAUTH != 1)
+#error "Feature test macro __ARM_FEATURE__PAUTH should be defined to 1."
+#endif
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-12.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-12.c
new file mode 100644
index 0000000..db40b17
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-12.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-skip-if "avoid conflicting multilib options" { *-*-* } { "-marm" "-mcpu=*" } } */
+/* { dg-options "-march=armv8-m.main+fp -mfloat-abi=softfp" } */
+
+#if defined (__ARM_FEATURE_BTI)
+#error "Feature test macro __ARM_FEATURE_BTI should not be defined."
+#endif
+
+#if defined (__ARM_FEATURE_PAUTH)
+#error "Feature test macro __ARM_FEATURE_PAUTH should not be defined."
+#endif
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-2.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-2.c
new file mode 100644
index 0000000..cd418ce
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-2.c
@@ -0,0 +1,24 @@
+/* { dg-do run } */
+/* { dg-require-effective-target mbranch_protection_ok } */
+/* { dg-require-effective-target arm_pacbti_hw } */
+/* { dg-options "-march=armv8.1-m.main+pacbti+fp -mbranch-protection=bti+pac-ret+leaf -mthumb -mfloat-abi=hard" } */
+
+#if !defined (__ARM_FEATURE_BTI_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be defined."
+#endif
+
+#if !defined (__ARM_FEATURE_PAC_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be defined."
+#endif
+
+int
+main()
+{
+  if (__ARM_FEATURE_BTI_DEFAULT != 1)
+    __builtin_abort ();
+
+  if (__ARM_FEATURE_PAC_DEFAULT != 5)
+    __builtin_abort ();
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-4.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-4.c
new file mode 100644
index 0000000..ce4b45a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-4.c
@@ -0,0 +1,20 @@
+/* { dg-do run } */
+/* { dg-require-effective-target arm_pacbti_hw } */
+/* { dg-options "-march=armv8.1-m.main+pacbti+fp -mbranch-protection=pac-ret -mthumb -mfloat-abi=hard" } */
+
+#if !defined (__ARM_FEATURE_PAC_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be defined."
+#endif
+
+#if defined (__ARM_FEATURE_BTI_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be undefined."
+#endif
+
+int
+main()
+{
+  if (__ARM_FEATURE_PAC_DEFAULT != 1)
+    __builtin_abort ();
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-5.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-5.c
new file mode 100644
index 0000000..6d48b7c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-5.c
@@ -0,0 +1,25 @@
+/* { dg-do run } */
+/* { dg-require-effective-target mbranch_protection_ok } */
+/* { dg-require-effective-target arm_pacbti_hw } */
+/* { dg-skip-if "do not override march" { *-*-* } { "-march=*" } { "-march=armv8.1-m.main" } } */
+/* { dg-additional-options "-march=armv8.1-m.main -mbranch-protection=bti+pac-ret" } */
+
+#if !defined (__ARM_FEATURE_BTI_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be defined."
+#endif
+
+#if !defined (__ARM_FEATURE_PAC_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be defined."
+#endif
+
+int
+main()
+{
+  if (__ARM_FEATURE_BTI_DEFAULT != 1)
+    __builtin_abort ();
+
+  if (__ARM_FEATURE_PAC_DEFAULT != 1)
+    __builtin_abort ();
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-8.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-8.c
new file mode 100644
index 0000000..3538c18
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-8.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target mbranch_protection_ok } */
+/* { dg-additional-options "-march=armv8.1-m.main+fp -mbranch-protection=bti+pac-ret+leaf -mfloat-abi=hard" } */
+
+#if (__ARM_FEATURE_BTI_DEFAULT != 1)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be defined to 1."
+#endif
+
+#if (__ARM_FEATURE_PAC_DEFAULT != 5)
+#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be defined to 5."
+#endif
+
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-9.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-9.c
new file mode 100644
index 0000000..27c1c8f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-9.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target mbranch_protection_ok } */
+/* { dg-additional-options "-march=armv8.1-m.main+fp -mbranch-protection=pac-ret -mfloat-abi=hard" } */
+
+#if (__ARM_FEATURE_PAC_DEFAULT != 1)
+#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be defined to 1."
+#endif
+
+#if defined (__ARM_FEATURE_BTI_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be undefined."
+#endif
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index a9ee288..c0694af 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -5218,6 +5218,16 @@ proc check_effective_target_arm_cmse_clear_ok {} {
     } "-mcmse"];
 }
 
+# Return 1 if this is an ARM target supporting
+# -mbranch-protection=standard, 0 otherwise.
+
+proc check_effective_target_mbranch_protection_ok {} {
+
+    return [check_no_compiler_messages mbranch_protection_ok object {
+	int main (void) { return 0; }
+    } "-mbranch-protection=standard"]
+}
+
 # Return 1 if the target supports executing PACBTI instructions, 0
 # otherwise.