This patch adds the -march feature +pacbti to Armv8.1-M Mainline.
This feature enables pointer signing and authentication instructions
on M-class architectures.
Pre-approved here
<https://gcc.gnu.org/pipermail/gcc-patches/2021-December/586144.html>.
gcc/Changelog:
* config/arm/arm.h (TARGET_HAVE_PACBTI): New macro.
* config/arm/arm-cpus.in (pacbti): New feature.
* doc/invoke.texi (Arm Options): Document it.
Co-Authored-By: Tejas Belagod <tbela...@arm.com>
diff --git a/gcc/config/arm/arm-cpus.in b/gcc/config/arm/arm-cpus.in
index 0d3082b569f..6c1dffe56e3 100644
--- a/gcc/config/arm/arm-cpus.in
+++ b/gcc/config/arm/arm-cpus.in
@@ -229,6 +229,10 @@ define feature cdecp5
define feature cdecp6
define feature cdecp7
+# M-profile control flow integrity extensions (PAC/AUT/BTI).
+# Optional from Armv8.1-M Mainline.
+define feature pacbti
+
# Feature groups. Conventionally all (or mostly) upper case.
# ALL_FPU lists all the feature bits associated with the floating-point
# unit; these will all be removed if the floating-point unit is disabled
@@ -748,6 +752,7 @@ begin arch armv8.1-m.main
option nofp remove ALL_FP
option mve add MVE
option mve.fp add MVE_FP
+ option pacbti add pacbti
option cdecp0 add cdecp0
option cdecp1 add cdecp1
option cdecp2 add cdecp2
diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
index f479540812a..3495ab857ea 100644
--- a/gcc/config/arm/arm.h
+++ b/gcc/config/arm/arm.h
@@ -335,6 +335,12 @@ emission of floating point pcs attributes. */
isa_bit_mve_float) \
&& !TARGET_GENERAL_REGS_ONLY)
+/* Non-zero if this target supports Armv8.1-M Mainline pointer-signing
+ extension. */
+#define TARGET_HAVE_PACBTI (arm_arch8_1m_main \
+ && bitmap_bit_p (arm_active_target.isa, \
+ isa_bit_pacbti))
+
/* MVE have few common instructions as VFP, like VLDM alias VPOP, VLDR, VSTM
alia VPUSH, VSTR and VMOV, VMSR and VMRS. In the same manner it updates few
registers such as FPCAR, FPCCR, FPDSCR, FPSCR, MVFR0, MVFR1 and MVFR2. All
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 3936aef69d0..079e34ed98c 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -21002,6 +21002,9 @@ Disable the floating-point extension.
@item +cdecp0, +cdecp1, ... , +cdecp7
Enable the Custom Datapath Extension (CDE) on selected coprocessors according
to the numbers given in the options in the range 0 to 7.
+
+@item +pacbti
+Enable the Pointer Authentication and Branch Target Identification Extension.
@end table
@item armv8-m.main
