aarch64: Add +pauth flag for Pointer Authentication feature

New -march option +pauth enables PAuth vel PAC (Pointer Authentication)
feature.

gas/ChangeLog

@@ -1,3 +1,11 @@
+2020-11-13  Przemyslaw Wirkus  <przemyslaw.wirkus@arm.com>
+
+	* NEWS: Update news.
+	* config/tc-aarch64.c: Add option +pauth to -march.
+	* doc/c-aarch64.texi: Update docs.
+	* testsuite/gas/aarch64/pac-feat.d: New test.
+	* testsuite/gas/aarch64/pac-feat.s: New test.
+
 2020-11-16  Przemyslaw Wirkus  <przemyslaw.wirkus@arm.com>
 
 	* NEWS: Update news.

gas/NEWS

@@ -32,6 +32,9 @@
 * Add support for +ls64 feature for -march in Armv8.7 AArch64. Add atomic
   64-byte load/store instructions for this feature.
 
+* Add support for +pauth (Pointer Authentication) feature for -march in
+  AArch64.
+
 * Add support for Intel TDX instructions.
 
 * Add support for Intel Key Locker instructions.

gas/config/tc-aarch64.c

@@ -9227,6 +9227,8 @@ static const struct aarch64_option_cpu_value_table aarch64_features[] = {
 			AARCH64_ARCH_NONE},
   {"flagm",		AARCH64_FEATURE (AARCH64_FEATURE_FLAGM, 0),
 			AARCH64_ARCH_NONE},
+  {"pauth",		AARCH64_FEATURE (AARCH64_FEATURE_PAC, 0),
+			AARCH64_ARCH_NONE},
   {NULL,		AARCH64_ARCH_NONE, AARCH64_ARCH_NONE},
 };
 

gas/doc/c-aarch64.texi

@@ -230,8 +230,10 @@ automatically cause those extensions to be disabled.
  @tab Enable Flag Manipulation instructions.
 @item @code{csre} @tab ARMv8-A @tab No
  @tab Enable Call Stack Recorder Extension.
-@item @code{ls64} @tab ARMv8-6 @tab ARMv8.7-A or later
+@item @code{ls64} @tab ARMv8.6-A @tab ARMv8.7-A or later
  @tab Enable 64 Byte Loads/Stores.
+@item @code{pauth} @tab ARMv8-A @tab No
+ @tab Enable Pointer Authentication.
 @end multitable
 
 @node AArch64 Syntax

gas/testsuite/gas/aarch64/pac-feat.d

@@ -0,0 +1,74 @@
+#name: PAUTH (Pointer authentication) feature
+#objdump: -dr
+
+.*:     file .*
+
+Disassembly of section \.text:
+
+0+ <.*>:
+.*:	dac10083 	pacia	x3, x4
+.*:	dac103e5 	pacia	x5, sp
+.*:	dac10483 	pacib	x3, x4
+.*:	dac107e5 	pacib	x5, sp
+.*:	dac10883 	pacda	x3, x4
+.*:	dac10be5 	pacda	x5, sp
+.*:	dac10c83 	pacdb	x3, x4
+.*:	dac10fe5 	pacdb	x5, sp
+.*:	dac11083 	autia	x3, x4
+.*:	dac113e5 	autia	x5, sp
+.*:	dac11483 	autib	x3, x4
+.*:	dac117e5 	autib	x5, sp
+.*:	dac11883 	autda	x3, x4
+.*:	dac11be5 	autda	x5, sp
+.*:	dac11c83 	autdb	x3, x4
+.*:	dac11fe5 	autdb	x5, sp
+.*:	dac123e5 	paciza	x5
+.*:	dac127e5 	pacizb	x5
+.*:	dac12be5 	pacdza	x5
+.*:	dac12fe5 	pacdzb	x5
+.*:	dac133e5 	autiza	x5
+.*:	dac137e5 	autizb	x5
+.*:	dac13be5 	autdza	x5
+.*:	dac13fe5 	autdzb	x5
+.*:	dac143e5 	xpaci	x5
+.*:	dac147e5 	xpacd	x5
+.*:	9ac33041 	pacga	x1, x2, x3
+.*:	9adf3041 	pacga	x1, x2, sp
+.*:	d71f0822 	braa	x1, x2
+.*:	d71f087f 	braa	x3, sp
+.*:	d71f0c22 	brab	x1, x2
+.*:	d71f0c7f 	brab	x3, sp
+.*:	d73f0822 	blraa	x1, x2
+.*:	d73f087f 	blraa	x3, sp
+.*:	d73f0c22 	blrab	x1, x2
+.*:	d73f0c7f 	blrab	x3, sp
+.*:	d61f08bf 	braaz	x5
+.*:	d61f0cbf 	brabz	x5
+.*:	d63f08bf 	blraaz	x5
+.*:	d63f0cbf 	blrabz	x5
+.*:	d65f0bff 	retaa
+.*:	d65f0fff 	retab
+.*:	d69f0bff 	eretaa
+.*:	d69f0fff 	eretab
+.*:	f8200441 	ldraa	x1, \[x2\]
+.*:	f8200441 	ldraa	x1, \[x2\]
+.*:	f87ff483 	ldraa	x3, \[x4, #-8\]
+.*:	f82014c5 	ldraa	x5, \[x6, #8\]
+.*:	f83ff507 	ldraa	x7, \[x8, #4088\]
+.*:	f8600528 	ldraa	x8, \[x9, #-4096\]
+.*:	f82007e2 	ldraa	x2, \[sp\]
+.*:	f87067e4 	ldraa	x4, \[sp, #-2000\]
+.*:	f8a00441 	ldrab	x1, \[x2\]
+.*:	f8a00441 	ldrab	x1, \[x2\]
+.*:	f8fff483 	ldrab	x3, \[x4, #-8\]
+.*:	f8a014c5 	ldrab	x5, \[x6, #8\]
+.*:	f8bff507 	ldrab	x7, \[x8, #4088\]
+.*:	f8e00528 	ldrab	x8, \[x9, #-4096\]
+.*:	f8a007e2 	ldrab	x2, \[sp\]
+.*:	f8f067e4 	ldrab	x4, \[sp, #-2000\]
+.*:	f8201c62 	ldraa	x2, \[x3, #8\]!
+.*:	f87ffca4 	ldraa	x4, \[x5, #-8\]!
+.*:	f83fffe6 	ldraa	x6, \[sp, #4088\]!
+.*:	f8a01c62 	ldrab	x2, \[x3, #8\]!
+.*:	f8fffca4 	ldrab	x4, \[x5, #-8\]!
+.*:	f8bfffe6 	ldrab	x6, \[sp, #4088\]!

gas/testsuite/gas/aarch64/pac-feat.s

@@ -0,0 +1,79 @@
+	/* ARMv8.3 Pointer authentication instructions.  */
+	.arch armv8-a+pauth
+
+	/* Basic instructions.  */
+	pacia x3, x4
+	pacia x5, sp
+	pacib x3, x4
+	pacib x5, sp
+	pacda x3, x4
+	pacda x5, sp
+	pacdb x3, x4
+	pacdb x5, sp
+
+	autia x3, x4
+	autia x5, sp
+	autib x3, x4
+	autib x5, sp
+	autda x3, x4
+	autda x5, sp
+	autdb x3, x4
+	autdb x5, sp
+
+	paciza x5
+	pacizb x5
+	pacdza x5
+	pacdzb x5
+
+	autiza x5
+	autizb x5
+	autdza x5
+	autdzb x5
+
+	xpaci x5
+	xpacd x5
+
+	pacga x1, x2, x3
+	pacga x1, x2, sp
+
+	/* Combined instructions.  */
+	braa x1, x2
+	braa x3, sp
+	brab x1, x2
+	brab x3, sp
+	blraa x1, x2
+	blraa x3, sp
+	blrab x1, x2
+	blrab x3, sp
+	braaz x5
+	brabz x5
+	blraaz x5
+	blrabz x5
+
+	retaa
+	retab
+	eretaa
+	eretab
+
+	ldraa x1, [x2]
+	ldraa x1, [x2,#0]
+	ldraa x3, [x4,#-8]
+	ldraa x5, [x6,#8]
+	ldraa x7, [x8,#4088]
+	ldraa x8, [x9,#-4096]
+	ldraa x2, [sp]
+	ldraa x4, [sp,#-2000]
+	ldrab x1, [x2]
+	ldrab x1, [x2,#0]
+	ldrab x3, [x4,#-8]
+	ldrab x5, [x6,#8]
+	ldrab x7, [x8,#4088]
+	ldrab x8, [x9,#-4096]
+	ldrab x2, [sp]
+	ldrab x4, [sp,#-2000]
+	ldraa x2, [x3, #8]!
+	ldraa x4, [x5, #-8]!
+	ldraa x6, [sp, #4088]!
+	ldrab x2, [x3, #8]!
+	ldrab x4, [x5, #-8]!
+	ldrab x6, [sp, #4088]!