aarch64: Update system register gating

Historically we have been inconsistent and overly restrictive in our
choice of features to gate system register accesses.  (Originally this
gating was always applied, but now it is disabled unless the
--menable-sysreg-checking option is specified).

This patch updates these constraints, following the principle that we
should only reject a system register access if it requires some
architecture feature or version whose corresponding command line
extension has not been enabled.

The most common change in this patch concerns system registers that
were:
- part of a feature FEAT_X with no corresponding command line extension;
- introduced in a newer architecture version ArmvX.Z;
- permitted to be implemented from an earlier version ArmvX.Y.
Previously these system registers tended to be gated on ArmvX.Z or left
ungated, but following the above principle they are now gated on ArmvX.Y
instead.

gas/testsuite/gas/aarch64/sysreg/armv8_9-a-sysregs-bad.d

@@ -1,3 +1,3 @@
 #source: armv8_9-a-sysregs.s
-#as: -menable-sysreg-checking -march=armv8.8-a -I$srcdir/$subdir --no-info
+#as: -menable-sysreg-checking -march=armv8.7-a -I$srcdir/$subdir --no-info
 #error_output: armv8_9-a-sysregs-bad.l

gas/testsuite/gas/aarch64/sysreg/armv8_9-a-sysregs-bad.l

@@ -2,14 +2,6 @@
 .*: Error: selected processor does not support system register name 'pmsdsfr_el1'
 .*: Error: selected processor does not support system register name 'pmsdsfr_el1'
 .*: Error: selected processor does not support system register name 'erxgsr_el1'
-.*: Error: selected processor does not support system register name 'sctlr2_el1'
-.*: Error: selected processor does not support system register name 'sctlr2_el1'
-.*: Error: selected processor does not support system register name 'sctlr2_el12'
-.*: Error: selected processor does not support system register name 'sctlr2_el12'
-.*: Error: selected processor does not support system register name 'sctlr2_el2'
-.*: Error: selected processor does not support system register name 'sctlr2_el2'
-.*: Error: selected processor does not support system register name 'sctlr2_el3'
-.*: Error: selected processor does not support system register name 'sctlr2_el3'
 .*: Error: selected processor does not support system register name 'hdfgrtr2_el2'
 .*: Error: selected processor does not support system register name 'hdfgrtr2_el2'
 .*: Error: selected processor does not support system register name 'hdfgwtr2_el2'
@@ -71,12 +63,6 @@
 .*: Error: selected processor does not support system register name 'por_el3'
 .*: Error: selected processor does not support system register name 's2por_el1'
 .*: Error: selected processor does not support system register name 's2por_el1'
-.*: Error: selected processor does not support system register name 'tcr2_el1'
-.*: Error: selected processor does not support system register name 'tcr2_el1'
-.*: Error: selected processor does not support system register name 'tcr2_el12'
-.*: Error: selected processor does not support system register name 'tcr2_el12'
-.*: Error: selected processor does not support system register name 'tcr2_el2'
-.*: Error: selected processor does not support system register name 'tcr2_el2'
 .*: Error: selected processor does not support system register name 'mdselr_el1'
 .*: Error: selected processor does not support system register name 'mdselr_el1'
 .*: Error: selected processor does not support system register name 'pmuacr_el1'
@@ -283,4 +269,4 @@
 .*: Error: selected processor does not support system register name 'pmecr_el1'
 .*: Error: selected processor does not support system register name 'pmecr_el1'
 .*: Error: selected processor does not support system register name 'pmiar_el1'
-.*: Error: selected processor does not support system register name 'pmiar_el1'
+.*: Error: selected processor does not support system register name 'pmiar_el1'

gas/testsuite/gas/aarch64/sysreg/armv8_9-a-sysregs.d

@@ -1,5 +1,5 @@
 #source: armv8_9-a-sysregs.s
-#as: -menable-sysreg-checking -march=armv8.9-a -I$srcdir/$subdir
+#as: -menable-sysreg-checking -march=armv9.4-a+profile -I$srcdir/$subdir
 #objdump: -dr
 
 .*:     file format .*

gas/testsuite/gas/aarch64/sysreg/armv9_5-a-sysregs-archv9_4-unsupported.d

@@ -1,3 +1,3 @@
 #source: armv9_5-a-sysregs.s
-#as: -menable-sysreg-checking -march=armv9.4-a -I$srcdir/$subdir
+#as: -menable-sysreg-checking -march=armv9.3-a -I$srcdir/$subdir
 #error_output: armv9_5-a-sysregs-archv9_4-unsupported.l

gas/testsuite/gas/aarch64/sysreg/illegal-sysreg-4.l

@@ -8,12 +8,6 @@
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'cvadp'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'rndr'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'rndrrs'
-[^:]*:[0-9]+: Error: selected processor does not support system register name 'scxtnum_el0'
-[^:]*:[0-9]+: Error: selected processor does not support system register name 'scxtnum_el1'
-[^:]*:[0-9]+: Error: selected processor does not support system register name 'scxtnum_el2'
-[^:]*:[0-9]+: Error: selected processor does not support system register name 'scxtnum_el3'
-[^:]*:[0-9]+: Error: selected processor does not support system register name 'scxtnum_el12'
-[^:]*:[0-9]+: Error: selected processor does not support system register name 'id_pfr2_el1'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'tco'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'tco'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'tfsre0_el1'

gas/testsuite/gas/aarch64/sysreg/illegal-sysreg-8.s

@@ -13,20 +13,19 @@
 
 	roreg	lorid_el1
 
-	.arch	armv8.2-a
+	.arch	armv8.1-a
 
 	roreg	ccsidr2_el1
+
+	.arch	armv8.2-a
+
 	rwreg	rcwmask_el1
 	rwreg	rcwsmask_el1
 
-	.arch	armv8.3-a
-
 	rwreg	trfcr_el1
 	roreg	pmmir_el1
 	rwreg	trfcr_el2
-
 	rwreg	trfcr_el12
-
 	rwreg	amcr_el0
 	roreg	amcfgr_el0
 	roreg	amcgcr_el0
@@ -76,7 +75,7 @@
 	rwreg	amevtyper114_el0
 	rwreg	amevtyper115_el0
 
-	.arch	armv8.5-a
+	.arch	armv8.4-a
 
 	roreg	amcg1idr_el0
 	roreg	cntpctss_el0
@@ -121,7 +120,7 @@
 	rwreg	amevcntvoff115_el2
 	rwreg	cntpoff_el2
 
-	.arch	armv8.6-a
+	.arch	armv8.5-a+profile
 
 	rwreg	pmsnevfr_el1
 	rwreg	hcrx_el2

gas/testsuite/gas/aarch64/sysreg/sme-sysreg.d

@@ -1,5 +1,5 @@
 #name: SME extension (system registers)
-#as: -menable-sysreg-checking -march=armv8-a+sme
+#as: -menable-sysreg-checking -march=armv8.2-a+sme
 #objdump: -dr
 
 .*:     file format .*

gas/testsuite/gas/aarch64/sysreg/sve-sysreg-invalid.l

@@ -1,6 +1,4 @@
 .*: Assembler messages:
-.*:1: Error: selected processor does not support system register name 'id_aa64zfr0_el1'
-.*:2: Error: selected processor does not support system register name 'id_aa64zfr0_el1'
 .*:4: Error: selected processor does not support system register name 'zcr_el1'
 .*:5: Error: selected processor does not support system register name 'zcr_el1'
 .*:6: Error: selected processor does not support system register name 'zcr_el1'

gas/testsuite/gas/aarch64/sysreg/sysreg-8.s

@@ -172,7 +172,7 @@
 	rw_sys_reg	amevcntvoff115_el2
 	rw_sys_reg	cntpoff_el2
 
-	.arch	armv8.7-a
+	.arch	armv8.7-a+profile
 
 	rw_sys_reg	pmsnevfr_el1
 	rw_sys_reg	hcrx_el2

gas/testsuite/gas/aarch64/sysreg/sysregs_with_no_restrictions-bad.l

@@ -1,10 +1,6 @@
 .*: Assembler messages:
 .*: Error: selected processor does not support system register name 'mpuir_el1'
 .*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'afsr0_el12'
-.*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'afsr0_el12'
-.*:  Info: macro invoked from here
 .*: Error: selected processor does not support PSTATE field name 'uao'
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'uao'
@@ -21,12 +17,6 @@
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'vsttbr_el2'
 .*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'scxtnum_el0'
-.*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'scxtnum_el0'
-.*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'id_pfr2_el1'
-.*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'amcg1idr_el0'
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'hcrx_el2'
@@ -83,18 +73,10 @@
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 's2por_el1'
 .*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'sctlr2_el1'
-.*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'sctlr2_el1'
-.*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'spmaccessr_el1'
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'spmaccessr_el1'
 .*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'tcr2_el1'
-.*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'tcr2_el1'
-.*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'amair2_el1'
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'amair2_el1'
@@ -125,8 +107,6 @@
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'fpmr'
 .*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'id_aa64zfr0_el1'
-.*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'lorc_el1'
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'lorc_el1'
@@ -137,8 +117,6 @@
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'gcspr_el0'
 .*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'id_aa64smfr0_el1'
-.*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'trcitecr_el1'
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'trcitecr_el1'
@@ -165,7 +143,3 @@
 .*:  Info: macro invoked from here
 .*: Error: selected processor does not support system register name 'rcwmask_el1'
 .*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'ttbr1_el2'
-.*:  Info: macro invoked from here
-.*: Error: selected processor does not support system register name 'ttbr1_el2'
-.*:  Info: macro invoked from here

gas/testsuite/gas/aarch64/sysreg/sysregs_with_restrictions.s

@@ -29,7 +29,7 @@
 	.arch armv8.8-a
 	rw_sys_reg allint   // V8_8A
 
-	.arch armv8.9-a
+	.arch armv8.9-a+profile
 	rw_sys_reg pfar_el1   // PFAR
 	rw_sys_reg pir_el1   // S1PIE
 	rw_sys_reg pmecr_el1   // SEBEP