aarch64: move bogus assertion

Asserting "idx" to be non-negative when subsequent code handles this
case is bogus. In fact the assertion triggers e.g. when mistakenly
using the arm32 comment character @ following an instruction.

While doing this I also noticed that despite there being local
variables "detail" and "idx", not all places where they could be used
did actually make use of them, so this is being adjusted at once.

Finally, for the code to be slightly more robust, also change
comparisons against -1 to such checking for a (non-)negative value.

gas/ChangeLog

@@ -1,3 +1,9 @@
+2014-10-21  Jan Beulich  <jbeulich@suse.com>
+
+	* config/tc-aarch64.c (output_operand_error_record): Move down
+	assertion of idx being non-negative. Use local variables when
+	available.
+
 2014-10-18  Alan Modra  <amodra@gmail.com>
 
 	PR 17493

gas/config/tc-aarch64.c

@@ -3939,11 +3939,11 @@ output_info (const char *format, ...)
 static void
 output_operand_error_record (const operand_error_record *record, char *str)
 {
-  int idx = record->detail.index;
-  const aarch64_opcode *opcode = record->opcode;
-  enum aarch64_opnd opd_code = (idx != -1 ? opcode->operands[idx]
-				: AARCH64_OPND_NIL);
   const aarch64_operand_error *detail = &record->detail;
+  int idx = detail->index;
+  const aarch64_opcode *opcode = record->opcode;
+  enum aarch64_opnd opd_code = (idx >= 0 ? opcode->operands[idx]
+				: AARCH64_OPND_NIL);
 
   switch (detail->kind)
     {
@@ -3955,20 +3955,22 @@ output_operand_error_record (const operand_error_record *record, char *str)
     case AARCH64_OPDE_RECOVERABLE:
     case AARCH64_OPDE_FATAL_SYNTAX_ERROR:
     case AARCH64_OPDE_OTHER_ERROR:
-      gas_assert (idx >= 0);
       /* Use the prepared error message if there is, otherwise use the
 	 operand description string to describe the error.  */
       if (detail->error != NULL)
 	{
-	  if (detail->index == -1)
+	  if (idx < 0)
 	    as_bad (_("%s -- `%s'"), detail->error, str);
 	  else
 	    as_bad (_("%s at operand %d -- `%s'"),
-		    detail->error, detail->index + 1, str);
+		    detail->error, idx + 1, str);
 	}
       else
-	as_bad (_("operand %d should be %s -- `%s'"), idx + 1,
+	{
+	  gas_assert (idx >= 0);
+	  as_bad (_("operand %d should be %s -- `%s'"), idx + 1,
 		aarch64_get_operand_desc (opd_code), str);
+	}
       break;
 
     case AARCH64_OPDE_INVALID_VARIANT:
@@ -4073,28 +4075,28 @@ output_operand_error_record (const operand_error_record *record, char *str)
       if (detail->data[0] != detail->data[1])
 	as_bad (_("%s out of range %d to %d at operand %d -- `%s'"),
 		detail->error ? detail->error : _("immediate value"),
-		detail->data[0], detail->data[1], detail->index + 1, str);
+		detail->data[0], detail->data[1], idx + 1, str);
       else
 	as_bad (_("%s expected to be %d at operand %d -- `%s'"),
 		detail->error ? detail->error : _("immediate value"),
-		detail->data[0], detail->index + 1, str);
+		detail->data[0], idx + 1, str);
       break;
 
     case AARCH64_OPDE_REG_LIST:
       if (detail->data[0] == 1)
 	as_bad (_("invalid number of registers in the list; "
 		  "only 1 register is expected at operand %d -- `%s'"),
-		detail->index + 1, str);
+		idx + 1, str);
       else
 	as_bad (_("invalid number of registers in the list; "
 		  "%d registers are expected at operand %d -- `%s'"),
-	      detail->data[0], detail->index + 1, str);
+	      detail->data[0], idx + 1, str);
       break;
 
     case AARCH64_OPDE_UNALIGNED:
       as_bad (_("immediate value should be a multiple of "
 		"%d at operand %d -- `%s'"),
-	      detail->data[0], detail->index + 1, str);
+	      detail->data[0], idx + 1, str);
       break;
 
     default: