Hi All,

At the beginning of the port it was decided that enabling features should always
come before disabling features. i.e. +foo should always be before any +nofoo.

For years now this has been relaxed in GCC but binutils has remained rather
strict.  This removes the restriction from gas as well giving users less
friction.

build on native hardware and regtested on
  aarch64-none-elf, aarch64-none-elf (32 bit host),
  aarch64-none-linux-gnu, aarch64-none-linux-gnu (32 bit host)

Cross-compiled and regtested on
  aarch64-none-linux-gnu, aarch64_be-none-linux-gnu

and no issues.

Ok for master?

Thanks,
Tamar

gas/ChangeLog:

2023-02-01  Tamar Christina  <tamar.christina@arm.com>

	* config/tc-aarch64.c (aarch64_parse_features): Remove feature ordering
	checks.
	* testsuite/gas/aarch64/opt_order.l: New test.
	* testsuite/gas/aarch64/opt_order.s: New test.
	* testsuite/gas/aarch64/opt_order_1.d: New test.
	* testsuite/gas/aarch64/opt_order_2.d: New test.
	* testsuite/gas/aarch64/opt_order_3.d: New test.
	* testsuite/gas/aarch64/opt_order_4.d: New test.
	* testsuite/gas/aarch64/opt_order_5.d: New test.
	* testsuite/gas/aarch64/opt_order_6.d: New test.

--- inline copy of patch -- 
diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index 2aeab6f958ac6435c528b4394412d6395932a6d5..0c2ffd7bb85dbf892f265b6b394de7709de2f60e 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -10234,11 +10234,7 @@ static int
 aarch64_parse_features (const char *str, const aarch64_feature_set **opt_p,
 			bool ext_only)
 {
-  /* We insist on extensions being added before being removed.  We achieve
-     this by using the ADDING_VALUE variable to indicate whether we are
-     adding an extension (1) or removing it (0) and only allowing it to
-     change in the order -1 -> 1 -> 0.  */
-  int adding_value = -1;
+  bool adding_value = false;
   aarch64_feature_set *ext_set = XNEW (aarch64_feature_set);
 
   /* Copy the feature set, so that we can modify it.  */
@@ -10269,31 +10265,20 @@ aarch64_parse_features (const char *str, const aarch64_feature_set **opt_p,
 
       if (optlen >= 2 && startswith (str, "no"))
 	{
-	  if (adding_value != 0)
-	    adding_value = 0;
+	  adding_value = 0;
 	  optlen -= 2;
 	  str += 2;
 	}
       else if (optlen > 0)
 	{
-	  if (adding_value == -1)
-	    adding_value = 1;
-	  else if (adding_value != 1)
-	    {
-	      as_bad (_("must specify extensions to add before specifying "
-			"those to remove"));
-	      return false;
-	    }
+	  adding_value = 1;
 	}
-
-      if (optlen == 0)
+      else if (optlen == 0)
 	{
 	  as_bad (_("missing architectural extension"));
 	  return 0;
 	}
 
-      gas_assert (adding_value != -1);
-
       for (opt = aarch64_features; opt->name != NULL; opt++)
 	if (strncmp (opt->name, str, optlen) == 0)
 	  {
diff --git a/gas/testsuite/gas/aarch64/opt_order.l b/gas/testsuite/gas/aarch64/opt_order.l
new file mode 100644
index 0000000000000000000000000000000000000000..94820513356d2d3c2a02c1f348e2c5423e43f1cd
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/opt_order.l
@@ -0,0 +1 @@
+#...
diff --git a/gas/testsuite/gas/aarch64/opt_order.s b/gas/testsuite/gas/aarch64/opt_order.s
new file mode 100644
index 0000000000000000000000000000000000000000..e0642b3a811ad7d944418f36e237e6fd87771051
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/opt_order.s
@@ -0,0 +1 @@
+UDOT    V0.2S, V0.8B, V0.8B
diff --git a/gas/testsuite/gas/aarch64/opt_order_1.d b/gas/testsuite/gas/aarch64/opt_order_1.d
new file mode 100644
index 0000000000000000000000000000000000000000..862f7be85f462bfc470a466e9652471d0d268652
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/opt_order_1.d
@@ -0,0 +1,4 @@
+# source: opt_order.s
+# as: -march=armv8.2-a+nodotprod+fp16+dotprod
+# objdump: -dr
+#...
diff --git a/gas/testsuite/gas/aarch64/opt_order_2.d b/gas/testsuite/gas/aarch64/opt_order_2.d
new file mode 100644
index 0000000000000000000000000000000000000000..77bd6c57ec9be2e24c3b673f4eccb2c0f7bfc16c
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/opt_order_2.d
@@ -0,0 +1,4 @@
+# source: opt_order.s
+# as: -march=armv8.2-a+fp16+nodotprod+dotprod
+# objdump: -dr
+#...
diff --git a/gas/testsuite/gas/aarch64/opt_order_3.d b/gas/testsuite/gas/aarch64/opt_order_3.d
new file mode 100644
index 0000000000000000000000000000000000000000..5b22090331d11965097a35bad181693c75d51f3c
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/opt_order_3.d
@@ -0,0 +1,4 @@
+# source: opt_order.s
+# as: -march=armv8.2-a+dotprod+fp16+dotprod
+# objdump: -dr
+#...
diff --git a/gas/testsuite/gas/aarch64/opt_order_4.d b/gas/testsuite/gas/aarch64/opt_order_4.d
new file mode 100644
index 0000000000000000000000000000000000000000..7ffe2a3011632fdcf25aa32eeb1bedbcc1f408ba
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/opt_order_4.d
@@ -0,0 +1,5 @@
+# source: opt_order.s
+# as: -march=armv8.2-a+nodotprod+fp16+nodotprod
+# objdump: -dr
+#error_output: opt_order.l
+#...
diff --git a/gas/testsuite/gas/aarch64/opt_order_5.d b/gas/testsuite/gas/aarch64/opt_order_5.d
new file mode 100644
index 0000000000000000000000000000000000000000..e7d057c77e7efa14caf55c96cba321e99c36ca21
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/opt_order_5.d
@@ -0,0 +1,5 @@
+# source: opt_order.s
+# as: -march=armv8.2-a+dotprod+fp16+nodotprod
+# objdump: -dr
+#error_output: opt_order.l
+#...
diff --git a/gas/testsuite/gas/aarch64/opt_order_6.d b/gas/testsuite/gas/aarch64/opt_order_6.d
new file mode 100644
index 0000000000000000000000000000000000000000..b39247de3b3c7261a700b96be8cfbf6b781cbb6b
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/opt_order_6.d
@@ -0,0 +1,5 @@
+# source: opt_order.s
+# as: -march=armv8.2-a+fp16+dotprod+nodotprod
+# objdump: -dr
+#error_output: opt_order.l
+#...




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