RISC-V: Clarify the behavior of .option arch directive.

* To be consistent with -march option, removed the "=" operator when
user want to reset the whole architecture string.  So the formats are,

.option arch, +<extension><version>, ...
.option arch, -<extension>
.option arch, <ISA string>

* Don't allow to add or remove the base extensions in the .option arch
directive.  Instead, users should reset the whole architecture string
while they want to change the base extension.

* The operator "+" won't update the version of extension, if the
extension is already in the subset list.

bfd/
	* elfxx-riscv.c (riscv_add_subset): Don't update the version
	if the extension is already in the subset list.
	(riscv_update_subset): To be consistent with -march option,
	removed the "=" operator when user want to reset the whole
	architecture string.  Besides, Don't allow to add or remove
	the base extensions in the .option arch directive.
gas/
	* testsuite/gas/riscv/option-arch-01.s: Updated since we cannot
	add or remove the base extensions in the .option arch directive.
	* testsuite/gas/riscv/option-arch-02.s: Likewise.
	* testsuite/gas/riscv/option-arch-fail.l: Likewise.
	* testsuite/gas/riscv/option-arch-fail.s: Likewise.
	* testsuite/gas/riscv/option-arch-01a.d: Set -misa-spec=2.2.
	* testsuite/gas/riscv/option-arch-01b.d: Likewise.
	* testsuite/gas/riscv/option-arch-02.d: Updated since the .option
	arch, + won't change the version of extension, if the extension is
	already in the subset list.
	* testsuite/gas/riscv/option-arch-03.s: Removed the "=" operator
	when resetting the whole architecture string.

8 files changed, 13 insertions, 9 deletions

diff --git a/gas/testsuite/gas/riscv/option-arch-01.s b/gas/testsuite/gas/riscv/option-arch-01.s
index 201f9b3..50285fc 100644
--- a/gas/testsuite/gas/riscv/option-arch-01.s
+++ b/gas/testsuite/gas/riscv/option-arch-01.s
@@ -5,6 +5,6 @@ add	a0, a0, a1
 add	a0, a0, a1
 frcsr	a0	# Should add mapping symbol with ISA here, and then dump it to frcsr.
 .option push
-.option arch, +i3p0, +m3p0, +d3p0
+.option arch, +m3p0, +d3p0
 .option pop
 .option pop
diff --git a/gas/testsuite/gas/riscv/option-arch-01a.d b/gas/testsuite/gas/riscv/option-arch-01a.d
index 59bc1d2..aed4ca8 100644
--- a/gas/testsuite/gas/riscv/option-arch-01a.d
+++ b/gas/testsuite/gas/riscv/option-arch-01a.d
@@ -1,4 +1,4 @@
-#as:
+#as: -misa-spec=2.2
 #source: option-arch-01.s
 #objdump: -d
 
diff --git a/gas/testsuite/gas/riscv/option-arch-01b.d b/gas/testsuite/gas/riscv/option-arch-01b.d
index 9a6c2c5..8f4284d 100644
--- a/gas/testsuite/gas/riscv/option-arch-01b.d
+++ b/gas/testsuite/gas/riscv/option-arch-01b.d
@@ -1,4 +1,4 @@
-#as:
+#as: -misa-spec=2.2
 #readelf: -A
 #source: option-arch-01.s
 
diff --git a/gas/testsuite/gas/riscv/option-arch-02.d b/gas/testsuite/gas/riscv/option-arch-02.d
index 0fe89ec..9ca013e 100644
--- a/gas/testsuite/gas/riscv/option-arch-02.d
+++ b/gas/testsuite/gas/riscv/option-arch-02.d
@@ -1,8 +1,8 @@
-#as:
+#as: -misa-spec=2.2
 #readelf: -A
 #source: option-arch-02.s
 
 Attribute Section: riscv
 File Attributes
-  Tag_RISCV_arch: "rv64i3p0_m3p0_f2p0_d3p0_c2p0_xvendor32x3p0"
+  Tag_RISCV_arch: "rv64i2p0_m3p0_f2p0_d3p0_c2p0_xvendor32x3p0"
 #...
diff --git a/gas/testsuite/gas/riscv/option-arch-02.s b/gas/testsuite/gas/riscv/option-arch-02.s
index f4ceee84..e0f5de3 100644
--- a/gas/testsuite/gas/riscv/option-arch-02.s
+++ b/gas/testsuite/gas/riscv/option-arch-02.s
@@ -5,4 +5,4 @@ add	a0, a0, a1
 add	a0, a0, a1
 frcsr	a0
 .option pop
-.option arch, +i3p0, +m3p0, +d3p0, +xvendor32x3p0
+.option arch, +m3p0, +d3p0, +xvendor32x3p0
diff --git a/gas/testsuite/gas/riscv/option-arch-03.s b/gas/testsuite/gas/riscv/option-arch-03.s
index 7183140..d982a0b 100644
--- a/gas/testsuite/gas/riscv/option-arch-03.s
+++ b/gas/testsuite/gas/riscv/option-arch-03.s
@@ -1,3 +1,3 @@
 .attribute arch, "rv64ic"
 .option arch, +d2p0, -c
-.option arch, =rv32ic
+.option arch, rv32ic
diff --git a/gas/testsuite/gas/riscv/option-arch-fail.l b/gas/testsuite/gas/riscv/option-arch-fail.l
index 3e0599e..b9979a4 100644
--- a/gas/testsuite/gas/riscv/option-arch-fail.l
+++ b/gas/testsuite/gas/riscv/option-arch-fail.l
@@ -1,6 +1,8 @@
 .*Assembler messages:
-.*Error: extensions must begin with \+/\-/\= in .option arch `m2p0'
-.*Error: cannot remove extension `i' in .option arch `\-i'
+.*Error: m2p0: ISA string must begin with rv32 or rv64
+.*Error: cannot \+ or \- base extension `i' in .option arch `\-i'
+.*Error: cannot \+ or \- base extension `e' in .option arch `\+e'
+.*Error: cannot \+ or \- base extension `g' in .option arch `\-g'
 .*Error: unknown ISA extension `zsubset' in .option arch `\+zsubset2p0'
 .*Error: unknown ISA extension `f2p0_d' in .option arch `\+f2p0_d2p0'
 .*Error: unknown ISA extension `' in .option arch `\+'
diff --git a/gas/testsuite/gas/riscv/option-arch-fail.s b/gas/testsuite/gas/riscv/option-arch-fail.s
index a0b1bde..101587a 100644
--- a/gas/testsuite/gas/riscv/option-arch-fail.s
+++ b/gas/testsuite/gas/riscv/option-arch-fail.s
@@ -2,6 +2,8 @@
 .option push
 .option arch, m2p0
 .option arch, -i
+.option arch, +e
+.option arch, -g
 .option arch, +zsubset2p0
 .option arch, +f2p0_d2p0
 .option arch, +