[PATCH 7/15] arm: Emit build attributes for PACBTI target feature

This patch emits assembler directives for PACBTI build attributes as
defined by the
ABI.

<https://github.com/ARM-software/abi-aa/releases/download/2021Q1/addenda32.pdf>

gcc/ChangeLog:

	* config/arm/arm.cc (arm_file_start): Emit EABI attributes for
	Tag_PAC_extension, Tag_BTI_extension, TAG_BTI_use, TAG_PACRET_use.

gcc/testsuite/ChangeLog:

	* gcc.target/arm/acle/pacbti-m-predef-1.c: New test.
	* gcc.target/arm/acle/pacbti-m-predef-3.c: Likewise.
	* gcc.target/arm/acle/pacbti-m-predef-6.c: Likewise.
	* gcc.target/arm/acle/pacbti-m-predef-7.c: Likewise.

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

5 files changed, 85 insertions, 0 deletions

diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
index 76c6f94..358b813 100644
--- a/gcc/config/arm/arm.cc
+++ b/gcc/config/arm/arm.cc
@@ -28478,6 +28478,8 @@ static void
 arm_file_start (void)
 {
   int val;
+  bool pac = (aarch_ra_sign_scope != AARCH_FUNCTION_NONE);
+  bool bti = (aarch_enable_bti == 1);
 
   arm_print_asm_arch_directives
     (asm_out_file, TREE_TARGET_OPTION (target_option_default_node));
@@ -28548,6 +28550,22 @@ arm_file_start (void)
 	arm_emit_eabi_attribute ("Tag_ABI_FP_16bit_format", 38,
 			     (int) arm_fp16_format);
 
+      if (TARGET_HAVE_PACBTI)
+	{
+	  arm_emit_eabi_attribute ("Tag_PAC_extension", 50, 2);
+	  arm_emit_eabi_attribute ("Tag_BTI_extension", 52, 2);
+	}
+      else if (pac || bti)
+	{
+	  arm_emit_eabi_attribute ("Tag_PAC_extension", 50, 1);
+	  arm_emit_eabi_attribute ("Tag_BTI_extension", 52, 1);
+	}
+
+      if (bti)
+        arm_emit_eabi_attribute ("TAG_BTI_use", 74, 1);
+      if (pac)
+	arm_emit_eabi_attribute ("TAG_PACRET_use", 76, 1);
+
       if (arm_lang_output_object_attributes_hook)
 	arm_lang_output_object_attributes_hook();
     }
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-1.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-1.c
new file mode 100644
index 0000000..122f7a7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-1.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target mbranch_protection_ok } */
+/* { dg-options "-march=armv8.1-m.main+fp -mbranch-protection=pac-ret+bti -mfloat-abi=hard --save-temps" } */
+
+#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
+
+/* { dg-final { scan-assembler-not "\.arch_extension pacbti" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 50, 1" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 52, 1" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 74, 1" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 76, 1" } } */
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-3.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-3.c
new file mode 100644
index 0000000..b94f344
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-3.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target mbranch_protection_ok } */
+/* { dg-options "-march=armv8.1-m.main+fp -mbranch-protection=pac-ret+leaf -mfloat-abi=hard --save-temps" } */
+
+#if defined (__ARM_FEATURE_BTI_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be undefined."
+#endif
+
+#if !defined (__ARM_FEATURE_PAC_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be defined."
+#endif
+
+/* { dg-final { scan-assembler-not "\.arch_extension pacbti" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 50, 1" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 52, 1" } } */
+/* { dg-final { scan-assembler-not "\.eabi_attribute 74" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 76, 1" } } */
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-6.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-6.c
new file mode 100644
index 0000000..ed52afc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-6.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target mbranch_protection_ok } */
+/* { dg-additional-options "-march=armv8.1-m.main+fp -mbranch-protection=bti -mfloat-abi=hard --save-temps" } */
+
+#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 undefined."
+#endif
+/* { dg-final { scan-assembler-not "\.arch_extension pacbti" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 50, 1" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 52, 1" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 74, 1" } } */
+/* { dg-final { scan-assembler-not "\.eabi_attribute 76" } } */
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-7.c b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-7.c
new file mode 100644
index 0000000..1b25907
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-7.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-skip-if "avoid conflicting multilib options" { *-*-* } { "-marm" "-mcpu=*" } } */
+/* { dg-additional-options "-march=armv8.1-m.main+pacbti+fp --save-temps -mfloat-abi=hard" } */
+
+#if defined (__ARM_FEATURE_BTI_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be undefined."
+#endif
+
+#if defined (__ARM_FEATURE_PAC_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be undefined."
+#endif
+
+/* { dg-final { scan-assembler "\.arch_extension pacbti" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 50, 2" } } */
+/* { dg-final { scan-assembler "\.eabi_attribute 52, 2" } } */
+/* { dg-final { scan-assembler-not "\.eabi_attribute 74" } } */
+/* { dg-final { scan-assembler-not "\.eabi_attribute 76" } } */