aarch64: Add +pauth to -march

New +pauth (Pointer Authentication from Armv8.3-A) feature option for
-march command line option.

Please note that majority of PAUTH instructions are implemented behind HINT
instruction. PAUTH stays an Armv8.3-A feature but now can be assigned to other
architectures or CPUs.

gcc/ChangeLog:

	* config/aarch64/aarch64-option-extensions.def
	(AARCH64_OPT_EXTENSION): New +pauth option in -march for AArch64.
	* config/aarch64/aarch64.h (AARCH64_FL_PAUTH): New pauth extension bitmask.
	(AARCH64_ISA_PUATH): New ISA bitmask for PAUTH.
	(AARCH64_FL_FOR_ARCH8_3): Add PAUTH to Armv8.3-A.
	(TARGET_PAUTH): New target mask to isolate PAUTH instructions.
	* config/aarch64/aarch64.md (do_return): Condition set to TARGET_PAUTH.
	* doc/invoke.texi: Update docs for +flagm and +pauth.

4 files changed, 17 insertions, 6 deletions

diff --git a/gcc/config/aarch64/aarch64-option-extensions.def b/gcc/config/aarch64/aarch64-option-extensions.def
index ec45301..7db0a9f 100644
--- a/gcc/config/aarch64/aarch64-option-extensions.def
+++ b/gcc/config/aarch64/aarch64-option-extensions.def
@@ -229,4 +229,7 @@ AARCH64_OPT_EXTENSION("bf16", AARCH64_FL_BF16, \
 /* Enabling/Disabling "flagm" only changes "flagm".  */
 AARCH64_OPT_EXTENSION("flagm", AARCH64_FL_FLAGM, 0, 0, false, "flagm")
 
+/* Enabling/Disabling "pauth" only changes "pauth".  */
+AARCH64_OPT_EXTENSION("pauth", AARCH64_FL_PAUTH, 0, 0, false, "paca pacg")
+
 #undef AARCH64_OPT_EXTENSION
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index 0bdcc74..6c145cb 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -227,6 +227,9 @@ extern unsigned aarch64_architecture_version;
 /* Flag Manipulation Instructions (FLAGM) extension.  */
 #define AARCH64_FL_FLAGM      (1ULL << 39)
 
+/* Pointer Authentication (PAUTH) extension.  */
+#define AARCH64_FL_PAUTH      (1ULL << 40)
+
 /* Has FP and SIMD.  */
 #define AARCH64_FL_FPSIMD     (AARCH64_FL_FP | AARCH64_FL_SIMD)
 
@@ -241,7 +244,7 @@ extern unsigned aarch64_architecture_version;
 #define AARCH64_FL_FOR_ARCH8_2			\
   (AARCH64_FL_FOR_ARCH8_1 | AARCH64_FL_V8_2)
 #define AARCH64_FL_FOR_ARCH8_3			\
-  (AARCH64_FL_FOR_ARCH8_2 | AARCH64_FL_V8_3)
+  (AARCH64_FL_FOR_ARCH8_2 | AARCH64_FL_V8_3 | AARCH64_FL_PAUTH)
 #define AARCH64_FL_FOR_ARCH8_4			\
   (AARCH64_FL_FOR_ARCH8_3 | AARCH64_FL_V8_4 | AARCH64_FL_F16FML \
    | AARCH64_FL_DOTPROD | AARCH64_FL_RCPC8_4 | AARCH64_FL_FLAGM)
@@ -290,6 +293,7 @@ extern unsigned aarch64_architecture_version;
 #define AARCH64_ISA_BF16	   (aarch64_isa_flags & AARCH64_FL_BF16)
 #define AARCH64_ISA_SB		   (aarch64_isa_flags & AARCH64_FL_SB)
 #define AARCH64_ISA_V8_R	   (aarch64_isa_flags & AARCH64_FL_V8_R)
+#define AARCH64_ISA_PAUTH	   (aarch64_isa_flags & AARCH64_FL_PAUTH)
 
 /* Crypto is an optional extension to AdvSIMD.  */
 #define TARGET_CRYPTO (TARGET_SIMD && AARCH64_ISA_CRYPTO)
@@ -378,6 +382,9 @@ extern unsigned aarch64_architecture_version;
 #define TARGET_BF16_SIMD (AARCH64_ISA_BF16 && TARGET_SIMD)
 #define TARGET_SVE_BF16 (TARGET_SVE && AARCH64_ISA_BF16)
 
+/* PAUTH instructions are enabled through +pauth.  */
+#define TARGET_PAUTH (AARCH64_ISA_PAUTH)
+
 /* Make sure this is always defined so we don't have to check for ifdefs
    but rather use normal ifs.  */
 #ifndef TARGET_FIX_ERR_A53_835769_DEFAULT
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index eed06de..6327ae0 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -873,7 +873,7 @@
   {
     const char *ret = NULL;
     if (aarch64_return_address_signing_enabled ()
-	&& TARGET_ARMV8_3
+	&& (TARGET_PAUTH)
 	&& !crtl->calls_eh_return)
       {
 	if (aarch64_ra_sign_key == AARCH64_KEY_B)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index f7e8c8b..8b871e8 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -18016,8 +18016,8 @@ and the features that they enable by default:
 @item @samp{armv8-a} @tab Armv8-A @tab @samp{+fp}, @samp{+simd}
 @item @samp{armv8.1-a} @tab Armv8.1-A @tab @samp{armv8-a}, @samp{+crc}, @samp{+lse}, @samp{+rdma}
 @item @samp{armv8.2-a} @tab Armv8.2-A @tab @samp{armv8.1-a}
-@item @samp{armv8.3-a} @tab Armv8.3-A @tab @samp{armv8.2-a}
-@item @samp{armv8.4-a} @tab Armv8.4-A @tab @samp{armv8.3-a}, @samp{+fp16fml}, @samp{+dotprod}
+@item @samp{armv8.3-a} @tab Armv8.3-A @tab @samp{armv8.2-a}, @samp{+pauth}
+@item @samp{armv8.4-a} @tab Armv8.4-A @tab @samp{armv8.3-a}, @samp{+flagm}, @samp{+fp16fml}, @samp{+dotprod}
 @item @samp{armv8.5-a} @tab Armv8.5-A @tab @samp{armv8.4-a}, @samp{+sb}, @samp{+ssbs}, @samp{+predres}
 @item @samp{armv8.6-a} @tab Armv8.6-A @tab @samp{armv8.5-a}, @samp{+bf16}, @samp{+i8mm}
 @item @samp{armv8-r} @tab Armv8-R @tab @samp{armv8-r}
@@ -18288,8 +18288,9 @@ Advanced SIMD and floating-point instructions.  This option is enabled by
 default for @option{-march=armv8.6-a}.  Use of this option with architectures
 prior to Armv8.2-A is not supported.
 @item flagm
-Enable the Flag Manipulation instructions Extension. This option is enabled by
-default for @option{-march=armv8.4-a}.
+Enable the Flag Manipulation instructions Extension.
+@item pauth
+Enable the Pointer Authentication Extension.
 
 @end table