[PATCH 5/12] arm: Implement target feature macros for PACBTI

[Andrea Corallo via Gcc-patches]

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/ChangeLog:

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

gcc/testsuite/ChangeLog:

        * gcc.target/arm/acle/pacbti-m-predef-2.c: New test.
        * gcc.target/arm/acle/pacbti-m-predef-4.c: New test.
        * gcc.target/arm/acle/pacbti-m-predef-5.c: New test.

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


diff --git a/gcc/config/arm/arm-c.cc b/gcc/config/arm/arm-c.cc
index a8697b8c62f..190099b2c37 100644
--- a/gcc/config/arm/arm-c.cc
+++ b/gcc/config/arm/arm-c.cc
@@ -212,6 +212,24 @@ 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-2.c 
b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-2.c
new file mode 100644
index 00000000000..4394fd147d7
--- /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 arm_pacbti_hw } */
+/* { dg-additional-options " -mbranch-protection=bti+pac-ret+leaf" } */
+
+#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 00000000000..90f0c724b9e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-4.c
@@ -0,0 +1,21 @@
+
+/* { dg-do run } */
+/* { dg-require-effective-target arm_pacbti_hw } */
+/* { dg-additional-options " -mbranch-protection=pac-ret" } */
+
+#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 00000000000..c865809b8b0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-5.c
@@ -0,0 +1,24 @@
+
+/* { dg-do run } */
+/* { dg-require-effective-target arm_pacbti_hw } */
+/* { dg-additional-options " -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;
+}