gas: sparc: allow ASR registers in the 0..31 range in V9 and later

In the SPARC V9 (and later) versions of the SPARC specification, the
section C.1.1 "Register Names" specifies that:

"asr_reg.  An asr_reg is an Ancillary State Register name.  It may have
 one of the following values:

  %asr16-%asr31"

The rationale of having this restriction was that the registers from 16
to 31 are reserved to implementations, and are therefore "non-V9".  It
also assumes that the existing ASR registers in the range 0..31 will
have their own names such as %y, that can be used to access such
registers.

However, this is problematic.  When a new ASR register is introduced,
such as %mcdper a.k.a. %asr14, it is useful to be able to use %asr14 in
order to not depend on the latest version of the assembler.

The Solaris assembler is lax and allows to assembly instructions
referring to %asr0 to %asr31.  This patch makes the GNU assembler to
mimic that behavior.

gas/ChangeLog:

  2016-03-24  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* config/tc-sparc.c (sparc_ip): Remove the V9 restriction on ASR
	registers to be in the 16..31 range.

2 files changed, 21 insertions, 16 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index f1f588e..493d779 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,8 @@
+2016-03-24  Jose E. Marchesi  <jose.marchesi@oracle.com>
+
+	* config/tc-sparc.c (sparc_ip): Remove the V9 restriction on ASR
+	registers to be in the 16..31 range.
+
 2016-03-24  Trevor Saunders  <tbsaunde+binutils@tbsaunde.org>
 
 	* config/tc-microblaze.c (md_assemble): Cast opc to char * when calling
diff --git a/gas/config/tc-sparc.c b/gas/config/tc-sparc.c
index 5d4e0d6..dfb84ef 100644
--- a/gas/config/tc-sparc.c
+++ b/gas/config/tc-sparc.c
@@ -1841,22 +1841,22 @@ sparc_ip (char *str, const struct sparc_opcode **pinsn)
 			  ++s;
 			}
 
-		      if (current_architecture >= SPARC_OPCODE_ARCH_V9)
-			{
-			  if (num < 16 || 31 < num)
-			    {
-			      error_message = _(": asr number must be between 16 and 31");
-			      goto error;
-			    }
-			}
-		      else
-			{
-			  if (num < 0 || 31 < num)
-			    {
-			      error_message = _(": asr number must be between 0 and 31");
-			      goto error;
-			    }
-			}
+                      /* We used to check here for the asr number to
+                         be between 16 and 31 in V9 and later, as
+                         mandated by the section C.1.1 "Register
+                         Names" in the SPARC spec.  However, we
+                         decided to remove this restriction as a) it
+                         introduces problems when new V9 asr registers
+                         are introduced, b) the Solaris assembler
+                         doesn't implement this restriction and c) the
+                         restriction will go away in future revisions
+                         of the Oracle SPARC Architecture.  */
+
+                      if (num < 0 || 31 < num)
+                        {
+                          error_message = _(": asr number must be between 0 and 31");
+                          goto error;
+                        }
 
 		      opcode |= (*args == 'M' ? RS1 (num) : RD (num));
 		      continue;